AERO No.

B O E I N G
21
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Contents Issue No. 21
FIRST-QUARTER 2003 – JANUARY

PERSPECTIVE 02 JERRY SMITH The Boeing Component

Exchange Program helps airlines reduce
fleet repair expenses and inventory
investment while improving schedule
reliability and stabilizing long-term
maintenance budget planning.
TECHNOLOGY/
PRODUCT DEVELOPMENT 03 GLOBAL NAVIGATION SATELLITE SYSTEM
A new positioning and landing system
that integrates satellite and ground-based
navigation information improves takeoff
and landing capability at reduced cost.

SAFETY 12 ERRONEOUS GLIDESLOPE Flight crews can

perform glideslope confidence checks to
help manage the risk of instrument landing
systems capturing erroneous glideslope
signals.
TECHNOLOGY/
PRODUCT DEVELOPMENT 19 747ER AND 747ER FREIGHTER The new
Longer Range 747-400 airplanes offer
significant range and payload improve-
ments and provide greater reliability,
maintainability, and flexibility.
TECHNOLOGY/
PRODUCT DEVELOPMENT 26 QUIET CLIMB The Boeing Quiet Climb
System is a new automated avionics
feature for quiet procedures that lessens
crew workload and helps airlines comply
with restrictions.

COVER 747-400ER
 PERSPECTIVE Three years ago, we
JERRY SMITH
introduced the Boeing
DIRECTOR
MAINTENANCE, REPAIR, AND COMPONENT MANAGEMENT
Component Exchange
BOEING COMMERCIAL AVIATION SERVICES Program, a service
designed to free car-
riers from costly fleet-support tasks without sacrificing airplane
schedule reliability. Today, seven airlines worldwide participate in
our program, experiencing substantial savings across their growing
fleets of 737-600/-700/-800/-900 airplanes.

With Component Exchange, we maintain Under the Component Exchange Program,

a dedicated inventory of selected high-value Next-Generation 737 operators sign up for
components so participating airlines don’t a term of up to 10 years, paying a rate
need to. Avionics, actuators, display units, that covers a potential exchange of
and other flight-critical parts can be on approximately 300 different LRUs. The rate
their way to airlines before mechanics is based on fleet size and flight-hours.
have even removed a damaged part from Supplier parts are included in the program.
an airplane. For more information about the
Instead of keeping multiple high-value Component Exchange Program, please
line replaceable units (LRU) in stock, airlines contact your Boeing Field Service repre-
maintain only minimal inventories of LRUs sentative or send us an e-mail message
and order exchange replacements from us, at repairs@boeing.com.
which we ship within one day. The airlines Our goal is to help you reduce your
send us their removed units, and we arrange inventory investment and improve schedule
for repair, modification, or overhaul through reliability.
a network of approved service providers. At Boeing, we are committed to your
The units are restored to airworthy condition, success.
upgraded to reflect design changes, and
returned to the exchange inventory pool,
where they are ready once again for any
customer in the program.
Participating airlines not only reduce
repair expenses and inventory holding
costs— which can run into the millions of
dollars— they also stabilize their long-term
maintenance budget planning.

2 AERO First-Quarter 2003 — January

 The aviation industry is developing a new posi-
tioning and landing system based on the Global
Navigation Satellite System (GNSS). The GNSS
landing system (GLS) integrates satellite and
ground-based navigation information to provide
the position information required for approach
and landing guidance. Potential benefits of the
GLOBAL NAVIGATION SATELLITE SYSTEM GLS include significantly improved takeoff and

LANDING
landing capability at airports worldwide and
at reduced cost, improved instrument approach
service at additional airports and runways,
and the eventual replacement of the Instrument

SYSTEM Landing System. Boeing plans to certify the

airborne aspects of GLS on the 737, to support
Category I operations, by the end of 2003.

TECHNOLOGY/PRODUCT DEVELOPMENT

JOHN ACKLAND
SENIOR TECHNICAL FELLOW
AIRPLANE SYSTEMS
BOEING COMMERCIAL AIRPLANES

TOM IMRICH
CHIEF PILOT
RESEARCH
BOEING COMMERCIAL AIRPLANES

TIM MURPHY
TECHNICAL FELLOW
SYSTEMS CONCEPT CENTER
BOEING COMMERCIAL AIRPLANES

AERO 3
 1 ELEMENTS OF THE GLS

The GLS consists of three major

elements — a global satellite constel-
lation that supports worldwide navi-
gation position fixing, a GBAS facility
at each equipped airport that provides
local navigation satellite correction
signals, and avionics in each airplane

F or more than 10 years, the

aviation industry has been
or an Air Traffic Service provider.
The GBAS service provides the
that process and provide guidance
and control based on the satellite and
GBAS signals (fig.1).
The GLS uses a navigation satellite
developing a positioning and land- radiated signal in space that can be constellation (e.g., the U.S. Global
ing system based on the Global used by suitably equipped airplanes Positioning System [GPS], the
Navigation Satellite System (GNSS). as the basis of a GNSS landing planned European Galileo System)
for the basic positioning service. The
These efforts culminated in late system (GLS). The initial SARPS
GPS constellation already is in place
2001, when the International Civil support an approach service. Future and improvements are planned over
Aviation Organization (ICAO) refinements should lead to full the coming decades. The Galileo con-
approved an international standard low-visibility service (i.e., takeoff, stellation is scheduled to be available
for a landing system based on local approach, and landing) and low- in 2008.
correction of GNSS data to a level visibility taxi operations. This The basic positioning service is
that would support instrument article describes augmented locally — at or near the
approaches. The ICAO Standards airport — through a GBAS radio
1. Elements of the GLS. transmitter facility. Because the ground
and Recommended Practices
facility is located at a known surveyed
(SARPS) define the characteristics 2. Operations using the GLS. point, the GBAS can estimate the
of a Ground-Based Augmentation errors contained in the basic position-
3. Benefits of the GLS.
System (GBAS) service that can ing data. Reference receivers in the
be provided by an airport authority 4. Operational experience. GBAS compare the basic positioning
data with the known position of the
facility and compute corrections
on a satellite-by-satellite basis. The
corrections are called pseudorange cor-
rections because the primary parameter
of interest is the distance between the
GBAS facility and individual satellites.
The satellite constellation is continu-
ously in motion, and satellites ascend
and descend over the horizon when
observed from any point on Earth.
The GBAS calculates corrections for
all the satellites that meet the specified
in-view criteria and transmits that
information to the nearby airplanes
over a VHF Data Broadcast (VDB)
data link.
Boeing airplanes that are currently
being produced contain Multi-Mode
Receivers (MMR) that support
Instrument Landing System (ILS) and
basic GPS operations. These MMRs

4 AERO First-Quarter 2003 — January

can be modified to support GLS and given a unique identifier for a particular
potentially Microwave Landing System 2 OPERATIONS USING THE GLS FAS, glideslope, and missed approach
operations. The GLS capability is combination. FAS data for all approach-
supported through the addition of a A single GBAS ground station typi- es supported by the particular GBAS
receiver and processing in the MMRs cally provides approach and landing facility are transmitted to the airplane
of the GBAS data provided through the service to all runways at the airport through the same high-integrity data
VDB data link. The MMRs apply the where it is installed. The GBAS may link as the satellite range correction
local correction data received from even provide limited approach service data (i.e., through the VDB data link).
the GBAS to each satellite that the to nearby airports. Each runway The MMRs process the pseudorange
airplane and GBAS share in common. approach direction requires the defini- correction and FAS data to produce an
Because of position and altitude tion of a final approach segment (FAS) ILS-like deviation indication from the
differences and local terrain effects, to establish the desired reference path final approach path. These deviations
the GBAS and the airplane may not for an approach, landing, and rollout. are then displayed on the pilot’s
necessarily be observing the same The FAS data for each approach are flight instruments (e.g., Primary Flight
combination of satellites. The airplane determined by the GBAS service pro- Display [PFD] ) and are used by air-
systems only use satellite information vider and typically are verified after plane systems such as the flight guid-
that is supported by correction data installation of the GBAS ground station. ance system (e.g., autopilot and flight
received from the GBAS. When the One feature that differentiates the director) for landing guidance.
airplane is relatively close to the GBAS GLS from a traditional landing system The ILS-like implementation of the
station, the corrections are most such as the ILS is the potential for mul- GLS was selected to support common
effective, and the MMRs can compute tiple final approach paths, glideslope flight deck and airplane systems in-
a very accurate position. Typical lateral angles, and missed approach paths tegration for both safety and economic
accuracy should be ≤1 m. for a given runway. Each approach is reasons. This implementation helps

1 THE GLS
FIGURE

Multi-Mode
Ground-Based
Receiver
VDB data link Augmentation
System
Corrections and
final approach
segment data

First-Quarter 2003 — January AERO 5

provide an optimal pilot and system 2 PFD WITH GLS
interface while introducing the GLS FIGURE
at a reasonable cost. The use of
operational procedures similar to those
established for ILS approach and land-
ing systems minimizes crew training,
facilitates the use of familiar instru-
ment and flight deck procedures, sim-
plifies flight crew operations planning,
and ensures consistent use of flight
deck displays and annunciations.
For example, the source of guidance
information (shown on the PFD in
fig. 2) is the GLS rather than the ILS.
The scaling of the path deviation
information on the pilot’s displays
for a GLS approach can be equivalent
to that currently provided for an ILS
approach. Hence, the pilot can monitor
a GLS approach by using a display
that is equivalent to that used during
an ILS approach.
Figure 2 shows a typical PFD
presentation for a GLS approach. The
Flight Mode Annunciation on the PFD
is “GLS” for a GLS approach and
“ILS” for an ILS approach.
To prepare for a GLS approach,
the pilot selects GLS as the navigation
source and chooses the particular GLS channel, and associated approach Figure 5 shows a typical GLS
approach to be flown. This is accom- identifier (fig. 3). approach procedure. The procedure is
plished by selecting a GLS approach Regardless of the selection method, similar to that used for ILS except for
through the FMS (fig. 3) or by entering the five-digit GLS channel number is the channel selection method and the
an approach designator on a dedicated encoded with the frequency to be used GLS-unique identifier. The approach
navigation control panel (fig. 4). In for the VDB data link receiver and with chart is an example of a Boeing flight-
either case, a unique five-digit channel an identifier for the particular approach test procedure and is similar to a chart
number is associated with each and missed approach path (FAS data that would be used for air carrier
approach. With the FMS interface, the set) that corresponds to the desired operations, with appropriate specifi-
pilot does not need to enter a channel approach. cation of the landing minima.
number; tuning is accomplished Figure 4 shows a navigation control Figure 6 is an example of a possible
automatically based on the approach panel used to tune navigation radios, future complex approach procedure
selected, just as is now done for ILS. including GLS, for the 737-600/-700/ using area navigation (RNAV),
However, for an airplane equipped -800/-900. Required Navigation Performance
with separate navigation tuning panels, The approach plate shows the (RNP), and GLS procedures in com-
the pilot tunes the MMRs by entering channel number for each approach and bination. Pilots could use such proce-
a GLS channel number in that panel. a four-character approach identifier to dures to conduct approaches in areas
This is similar to the equivalent ILS ensure consistency between the selected of difficult terrain, in adverse weather,
flight deck interface where a pilot channel and the approach procedure or where significant nearby airspace
tunes the ILS by using a designated chosen by the pilot. The approach restrictions are unavoidable. These
VHF navigation frequency. As with identifier is read from the FAS data procedures would combine an RNP
the ILS, certain GLS identification block and displayed to the pilot on the transition path to a GLS FAS to the
data are available on other FMS pages PFD to provide positive confirmation runway. These procedures can also
such as the APPROACH REF page, that the desired approach has indeed use GBAS position, velocity, and time
which shows the runway identifier, been selected. (PVT) information to improve RNP

6 AERO First-Quarter 2003 — January

 3 FMS APPROACH SELECTION INTERFACE EXAMPLES uses of GNSS positioning such as
FIGURE
Automatic Dependent Surveillance —
Broadcast and Surface Movement
Example APPROACH REF page with GLS Guidance and Control Systems.
The accuracy of the GBAS service
may support future safety enhance-
ments such as a high-quality electronic
taxi map display for pilot use in bad
weather. This could help reduce run-
way incursion incidents and facilitate
airport movements in low visibility.
The service also may support auto-
mated systems for runway incursion
detection or alerting.
As important as the accuracy of the
GBAS service is the integrity moni-
toring provided by the GBAS facility.
Any specific level of RNP operation
within GBAS coverage should be more
available because the user receivers
Example ARRIVALS page with GLS no longer will require redundant
satellites for satellite failure detection
(e.g., Receiver Autonomous Integrity
Monitoring).
Because the GBAS PS is optional
for ground stations under the ICAO
standards, some ground stations may
only provide PT 1 service. The
messages uplinked through the VDB
data link indicate whether or not the
ground station supports the GBAS PS
and specify the level of service for
each approach for which a channel
number has been assigned. When
the GBAS PS is provided, a specific
five-digit channel number is assigned
to allow selection of a non-approach-
specific GBAS PS from that station.
Consequently, the channel selection
capability and more accurately deliver ILS ground station supporting Category process allows different users to
the airplane to the FAS. I approaches. The PT 1 level was select different approaches and levels
The GBAS is intended to support developed to initially support approach of service.
multiple levels of service to an unlimited and landing operations for Category I The GBAS PS and the PT 1 service
number of airplanes within radio instrument approach procedures. are not exclusive. If the ground station
range of the VDB data link. Currently, However, this level also may support provides the GBAS PS, selecting a
ICAO has defined two levels of other operations such as guided takeoff channel number associated with any
service: Performance Type 1 (PT 1) and airport surface position determina- particular approach automatically
service and GBAS Positioning Service tion for low-visibility taxi. will enable the GBAS PS service. The
(GBAS PS). PT 1 service supports The GBAS PS provides for very receiver provides corrected PVT in-
ILS-like deviations for an instrument accurate PVT measurements within the formation to intended airplane systems
approach. The accuracy, integrity, and terminal area. This service is intended as long as the GBAS PS is enabled.
continuity of service for the PT 1 level to support FMS-based RNAV and ILS-like deviations also are available
have been specified to be the same as RNP-based procedures. The improved when the airplane is close enough to
or better than ICAO standards for an accuracy will benefit other future the selected approach path.

First-Quarter 2003 — January AERO 7

 4 GLS AS ACTIVE a large flat area in front
FIGURE
of the ILS glideslope
alone can represent a very
significant savings in site
preparation cost and opens
up many more locations
for low-minima instrument
approach service.
Although GBAS
accuracy can be affected
by multipath interference,
careful siting of GBAS
receivers can readily
eliminate multipath
concerns because GBAS
receivers do not need to
be placed near a runway
ICAO is continuing development From the service provider perspec- in a specific geometry, as is the case
of a specification for service levels tive, the GBAS can potentially provide with the ILS or MLS. Hence, this
that would support Category II and III several significant advantages over the virtually eliminates the requirements
approaches. ILS. First, significant cost savings may for critical protection areas or restricted
be realized because a single system areas to protect against signal interfer-
3 BENEFITS OF THE GLS may be able to support all runways at
an airport. With the ILS, each runway
ence on runways and nearby taxiways.
Finally, the GBAS should have less
From the user perspective, the GBAS served requires an ILS and a frequency frequent and less costly flight inspec-
service can offer significantly better assignment for that ILS, which can tion requirements than the ILS because
performance than an ILS. The guidance be difficult because of the limited the role of flight inspection for GBAS
signal has much less noise because numbers of available frequencies. is different. Traditional flight inspec-
there are no beam bends caused by Operational constraints often occur tion, if needed at all, primarily would
reflective interference (from buildings with the ILS when an Air Traffic apply only during the initial installation
and vehicles). However, the real value Service provider needs to switch a and ground station commissioning.
of the GLS is the promise of addi- commonly used ILS frequency to serve This flight inspection would verify the
tional or improved capabilities that the a different runway direction. This is not suitability of the various approach path
ILS cannot provide. For example, an issue with the GBAS because ample (FAS) definitions and ensure that the
the GLS can channels are available for assignment GBAS-to-runway geometry definitions
to each approach. In addition, because are correct. Because verifying the
■ Provide approach and takeoff guid- the GBAS serves all runway ends with coverage of the VDB data link prin-
ance service to multiple runways a single VHF frequency, the limited cipally is a continuity of service issue
through a single GBAS facility. navigation frequency spectrum is rather than an accuracy or integrity
■ Optimize runway use by reducing used much more efficiently. In fact, issue, it typically would not require
the size of critical protection areas a GBAS may even be able to support a periodic inspection.
for approach and takeoff operations significant level of instrument approach GBAS systems capable of sup-
compared with those needed for ILS. and departure operations at other porting Category II and III operations
nearby airports. internationally are envisioned. Airborne
■ Provide more flexible taxiway or The siting of GBAS ground stations system elements that would be neces-
hold line placement choices.
is considerably simpler than for the ILS sary for the enhanced GLS capability
■ Simplify runway protection because GBAS service accuracy is not (e.g., MMR and GLS automatic land-
constraints. degraded by any radio frequency prop- ing provisions) already are well on the
agation effects in the VHF band. way to certification or operational
■ Provide more efficient airplane
Unlike the ILS, which requires level authorization. Airborne systems and
separation or spacing standards for
ground and clear areas on the runway, flight deck displays eventually will
air traffic service provision.
the siting of a GBAS VHF transmitter evolve to take full advantage of the
■ Provide takeoff and departure guid- can be more flexible than ILS. The linear characteristic of the GLS over
ance with a single GBAS facility. removal of the requirement to provide the angular aspects of the ILS.

8 AERO First-Quarter 2003 — January

 5 TYPICAL GLS APPROACH PROCEDURE
OPERATIONAL
FIGURE
4 EXPERIENCE
To date, flight-test and operational
experience with the GLS has
been excellent. Many GLS-guided
approaches and landings have
been conducted successfully at
a variety of airports and under
various runway conditions.
Both automatic landings and
landings using head-up displays
have been accomplished safely
through landing rollout, in both
routine and non-normal conditions.
On the pilot’s flight displays,
the GLS has been unusually steady
and smooth when compared with
the current ILS systems even when
critical areas necessary for the
ILS approaches were unprotected
during the GLS approaches.
The Boeing Technology
Demonstrator program has
used a 737-900 to demonstrate
successful GLS operations to
airline customers, airplane and
avionics manufacturers, airport
authorities, Air Traffic Service
providers, and regulatory
authority representatives.
The GLS represents a mature
capability ready for widespread
operational implementation.
When implemented, the GLS will
improve safety, increase capacity,
and provide operational benefits
to airlines, pilots, passengers,
airports, and Air Traffic Service
providers. Boeing plans to certify
the airborne aspects of the GLS
on the 737 by the end of 2003
to support Category I operations,
with other models to follow.
Work is continuing for the
airborne certification of the GLS
to support Category II and III
operations when suitable GBAS
ground facilities are specified
and made available.

First-Quarter 2003 — January AERO 9

 POTENTIAL FUTURE APPROACH PROCEDURE
6 USING BOTH RNP AND GLS CAPABILITY
FIGURE

SUMMARY
The aviation industry
is developing the GLS, a
new positioning and landing
system that integrates
satellite and ground-based
navigation information.
Potential benefits of the
GLS include significantly
improved takeoff and
landing capability at air-
ports worldwide at reduced
cost, instrument approach
service at additional
airports and runways, and
eventual replacement of
the ILS. Boeing plans to
certify the airborne aspects
of the GLS on the 737 by
the end of 2003 to support
Category I operations, with
other models to follow.

10 AERO First-Quarter 2003 — January

 John Ackland
has worked on airplane
system design and devel-
About the Authors opment for the Concorde,
L-1011, DC-10, and all
current Boeing production
airplanes. A Boeing em-
ployee since 1980, he is a
Senior Technical Fellow and
participates in a number of
aviation industry committees
and organizations that are
working to improve the
aviation business.

Capt. Thomas Imrich

has held a variety of positions
in the FAA, including national
resource specialist for Air
Carrier Operations, where he
helped formulate and imple-
ment international flight safety
and operations policies for areas
such as navigation systems,
all-weather operations, and
crew qualification. He currently
serves as Chief Pilot, Research
for Boeing as a qualified airline
transport pilot and flight
instructor who is type rated in
the B737 through A340, MD-11,
B747-400, and B777.

Tim Murphy
is a Technical Fellow
supporting the Airplane
Systems Concept Center
with work on next-generation
communications, navigation,
and surveillance (CNS)
technologies for Air Traffic
Management with a focus
on GPS landing systems,
modernization, and augmen-
tation. He is active in devel-
oping international satellite
navigation standards for
commercial aviation.

First-Quarter 2003 — January AERO 11

 All airplanes equipped
with instrument landing
systems are vulnerable
to capturing erroneous
glideslope signals.
Boeing, the International
Civil Aviation Organization,
and the U.S. Federal
Aviation Administration
are working together
to improve awareness
and prevent such errors.
Flight crews can help
manage the risk by
understanding the problem
and performing glideslope
confidence checks.
SAFETY
DAVID CARBAUGH CAPT. BRYAN WYNESS
CHIEF PILOT VICE PRESIDENT
FLIGHT OPERATIONS SAFETY FLIGHT OPERATIONS
BOEING COMMERCIAL AIRPLANES AIR NEW ZEALAND

12 AERO First-Quarter 2003 — January

First-Quarter 2003 — January AERO 13
W
INCIDENT INVOLVING AN
ith the advent of instru- and the U.S. Federal Aviation 1 ERRONEOUS GLIDESLOPE SIGNAL
ment landing systems Administration (FAA) to address
On the night of July 29, 2000, an
(ILS) in the 1940s came maintenance errors that can cause
Air New Zealand 767 was on a routine
the possibility of erroneous or false erroneous glideslope signals. The flight from Auckland, New Zealand,
glideslope indications under certain subtle nature of the indications to Apia, Western Samoa. The night was
circumstances. One such erro- makes it imperative that flight crews moonless, with scattered clouds that
neous indication recently occurred also help manage the risk by under- prevented visibility of the runway lights.
on several 767, 777, and Airbus standing the problem and performing The flight crew members were expe-
airplanes, resulting in coupled ILS glideslope confidence checks. rienced in conducting routine automatic
approaches being flown toward a This article describes landing approaches in low visibility.
point short of the runway. This They considered a routine automatic
kind of problem can occur on any 1. Incident involving an landing approach to be safe if the
erroneous glideslope signal. autopilot was coupled to the airplane,
airplane with any ILS receiver.
no warning indications were visible,
Boeing has taken action to help 2. Causes of erroneous and a valid Morse code identifier signal
prevent such incidents by revising glideslope signals. came from the ground navigation aids.
operations manuals and working Well prepared before descent, the
3. Flight crew actions.
with the International Civil flight crew thoroughly briefed for
Aviation Organization (ICAO) 4. Industry actions. the approach. When the crew selected

1 COMPONENTS OF TYPICAL ILS GROUND EQUIPMENT

FIGURE

Amplifier 1

Primary Backup
transmitter transmitter Monitor

Amplifier 2

Control tower

14 AERO First-Quarter 2003 — January

 2 ADI: INDICATING ABOVE, AT, AND BELOW GLIDEPATH It is important to note
FIGURE
that, because the Morse
code identifier signal
is carried only on the
localizer carrier signal,
the flight crew only
knows whether or not
the localizer is transmit-
ting. No information on
the health of the glide-
slope, localizer, or other
functions is provided.
On the night of
July 29, 2000, the
glideslope sidelobe
the approach mode, the glideslope cap- these causes requires a discussion of amplifier was not operating in Apia. In
ture occurred almost immediately. All the ILS and its normal operation. addition, the ILS ground equipment had
ILS indications appeared to be correct. ILS ground equipment provides been left in bypass mode following cali-
With all three autopilots engaged, the horizontal and vertical guidance in- bration maintenance. This prevented sys-
captain concentrated on configuring formation to airplane instrumentation. tem transfer to the standby transmitter.
the airplane and slowing it for landing. The equipment typically comprises No alarm sounded in the control tower
The crew attributed the slightly steep five components: a localizer transmis- because the cable that fed information
descent of the airplane to its heavy sion system, a glideslope transmission to the tower navigation status displays
weight and tailwinds. The crew noted system, a DME or marker system, had been cut during construction. As
a good Morse code identifier signal a standby transmitter, and a remote a result, the Air New Zealand flight re-
and no warning indications. At 1,000 ft, control and indicator system (fig. 1). ceived only the glideslope carrier wave
the crew completed the landing checks. During normal ILS operation, the transmission, which was interpreted by
Shortly thereafter, the first officer localizer and glideslope transmitters the instruments as being on glideslope,
observed the close proximity of each radiate a carrier wave of 90- with no warning indications.
the island and 150-Hz signals of equal amplitude.
lights out his These signals alone do not provide
side window. guidance but are compared with sep-
3 FLIGHT CREW ACTIONS
The captain arate 90- and 150-Hz sidelobe signals The Air New Zealand incident exempli-
noticed that radiated by the localizer and glideslope fies why flight crews need to be aware
the distance to create complex interference patterns. of the potential for erroneous glideslope
measuring The patterns are designed so that
signals, even when the ILS is indicating
equipment when an airplane is below the desired
correctly and a distance-altitude check
(DME) glideslope, the instruments will sense
indications is performed at glideslope capture. Fre-
a predominance of 150-Hz signals;
differed slightly from what he would quent crosschecks and crew vigilance
when the airplane is above the desired
have expected. are key in detecting potential problems.
glideslope, the instruments will sense
The captain executed a timely a predominance of 90-Hz signals; and Crosschecks.
go-around 5.5 mi from the runway when the airplane is on the glideslope, A single distance-altitude check does
at an altitude of less than 400 ft. The the instruments will sense equal amounts not guarantee the subsequent descent
crew successfully executed a second of 90- and 150-Hz signals (fig. 2).
approach by using the localizer and path will be correct. Similarly, a single
The ILS was designed to protect
ignoring the on-glideslope indications. altitude check crossing the outer marker
against transmitter malfunctions. If a pri-
does not guarantee the glideslope is
mary transmitter malfunctions, the system
CAUSES OF ERRONEOUS correct. The best strategy is to cross-
2 GLIDESLOPE SIGNALS
automatically will transfer to the standby
transmitter. If the ILS does not change
check the airplane altitude against
distance periodically during descent.
Investigation of the Air New Zealand over to the standby transmitter, or if the
Methods to accomplish this include
incident revealed important informa- standby transmitter is faulty, the system
tion about the causes of erroneous automatically will shut down, and an ■ Crosschecking altitude and
glideslope signals. Understanding alarm will sound in the control tower. DME distance periodically.
First-Quarter 2003 — January AERO 15
■ Crosschecking altitude and flight 3 NZ 60 GO-AROUND
management system (FMS) FIGURE
threshold distance.
■ Crosschecking altitude and the
crossing altitude of the outer marker
(or locator, very-high-frequency omni-
range [VOR] navigation equipment,
or FMS).
■ Crosschecking radio altitude and
barometric altitude.
■ Crosschecking ground speed and
rate of descent.
■ Questioning air traffic controllers when
indications do not appear to be correct.
Similar erroneous indications can
occur with the localizer signal. Cross-
checking the signal with other navi-
gation indicators, such as VOR and
navigation database course heading
and tracking information, can help
reduce risks in such occurrences.
Crew vigilance.
Human factors were very important in
the successful outcome of the Air New
Zealand incident. Crewmembers were
alert to possible ILS problems because
have included issuing maintenance or through an automated terminal
guidance, improving equipment, information service (ATIS), that ILS
revising flight crew training manuals maintenance testing is in progress
and operations manuals, and facilitating and that the flight crew should not
discussions at industry safety forums. use the glideslope or localizer.
Maintenance guidance. ■ Recommends that maintenance
personnel turn off the glideslope
ICAO and the FAA have released guid-
notice to airmen (NOTAM) bulletins transmitter during localizer testing
ance for the proper conduct of ILS ground
had informed them that the ILS was and turn off the localizer transmitter
maintenance activities. The guidance
unmonitored, and they discussed this during glideslope testing.
■ Clarifies the content of NOTAMs
during their approach briefings. They Equipment improvements.
that are sent when maintenance work
also paid attention to subtle cues that In the case of the Air New Zealand
is in progress and the possibility of
something might be wrong, even though
false indications prohibits the use flight, the ground proximity warning
the automatic flight system was indica-
of a particular approach aid. system (GPWS) did not warn the crew
ting normally. Last, the crewmembers
flying the erroneous glideslope. This
were willing to execute a go-around ■ Recommends that maintenance
to give them more time to sort through is because the airplane did not have an
personnel confirm whether or not a
the conflicting information (fig. 3). NOTAM has been issued before excessive closure rate with terrain and
beginning ILS maintenance testing. the flaps were in landing configuration.
However, an airplane equipped with
4 INDUSTRY ACTIONS ■ Recommends that the Morse code iden- a terrain awareness warning system
tification feature be suspended when (TAWS) (e.g., the Honeywell enhanced
Boeing, the FAA, ICAO, and others
maintenance testing is in progress. GPWS) would have warned the crew
in the aviation industry are working
together to address the problem of ■ Recommends that air traffic control of the situation because TAWS compares
erroneous glideslope indications. Actions advise the flight crew, either by voice the flight path with a terrain database.

16 AERO First-Quarter 2003 — January

TAWS is standard equipment on all
in-production Boeing airplanes and is
About the Authors
available for retrofit on all models
delivered before 2000.
Training.
In addition to improving equipment,
Boeing has revised its flight crew train-
Capt. David Carbaugh
ing manuals and operations manuals and
is a 10,000-hour pilot, flying
has sent all airline customers a 26-min
CD-ROM video, “New Zealand 60 — 737, 757, 767, and 777 airplanes.
A Free Lesson.” The video and revised He is responsible for Boeing
manuals detail the problem of and solu- flight operations safety-related
tions to erroneous glideslope indications. activities and leads industry
teams on safety initiatives.
Safety forums.
Boeing also promotes discussion of
erroneous glideslope indications in vari-
ous industry safety forums worldwide.

Editor’s note: Additional copies of the training

video, “New Zealand 60 — A Free Lesson,” may
be obtained from the Flight Safety Foundation,
601 Madison St., Suite 300, Alexandria, VA 22314;
telephone 703-739-6700; fax 703-739-6708;
web site www.flightsafety.org.

SUMMARY
The transmission of erroneous ILS
information at Apia on July 29, 2000,
was caused by an unusual set of circum-
stances. However, technicians will con-
tinue to conduct testing and maintenance
of airfield navigation aids. A similar
situation could occur in any ILS-equipped
airplane during what appears to be a Capt. Bryan Wyness
routine instrument approach. has had a 38-year career
The best defenses against erroneous with Air New Zealand,
glideslope indications are understanding flying jets that include the
how the ILS works, equipping airplanes 747-400. As vice president
with modern warning systems, and im- of Flight Operations, he has
plementing training and procedures that responsibility for manag-
ensure crewmembers are prepared to take ing Air Operations and
appropriate action. Flight crew action Supporting Ground Operations
should include crosschecking the airplane for Air New Zealand.
altitude against distance periodically
during descent.
Special recognition is given to in-
vestigators David Stobie, Rod Smith,
Chris Kriechbaum, Bob Henderson, Joey
Anca, and Dr. Gordon Vette for their con-
tributions to understanding this incident.

First-Quarter 2003 — January AERO 17

 747ER 747
INTRODUCING THE AND

18 AERO First-Quarter 2003 — January

ER FREIGHTER

KURT KRAFT
PROGRAM MANAGER
LONGER RANGE 747 PROGRAM
BOEING COMMERCIAL AIRPLANES

TECHNOLOGY/PRODUCT DEVELOPMENT
The Longer Range 747-400 airplanes — the 747-400 Extended Range and 747-400
Extended Range Freighter — are the newest members of the 747 family. Through
structural and system enhancements, these airplanes offer significant improvements
in range and payload and provide greater reliability, maintainability, and flexibility.

First-Quarter 2003 — January AERO 19

 The 747-400ER Freighter was spare parts as standard 747-400s;

T he 747-400 Extended Range

launched in April 2001, with a five-
airplane order from International
Lease Finance Corporation. The first
and 747-400 Extended Range 747-400ER Freighter rollout was
Freighter are the newest members of in September 2002, with the first de-
new parts were made to be one-way
interchangeable with existing parts.
The new airplanes also have a com-
mon type rating with the 747-400
and 747-400 Freighter, which
the 747 family. The same size as livery in October 2002 to Air France. minimizes flight crew training
today’s 747-400 airplanes, the Longer The 747-400ER and 747-400ER requirements and disruptions to
Range 747-400s provide additional Freighter can be configured with flight operations.
range or greater payload, allowing General Electric CF6-80C2B5F, The most significant differences
airlines and cargo carriers to fly Pratt & Whitney 4062, or Rolls- between the standard 747-400
longer routes or carry more cargo Royce RB211-524H2-T engines. and the newest members of the
and passengers on existing routes. (The General Electric and Pratt & 747 family are
The Longer Range 747-400 Whitney engines are offered on the
1. Systems and structural revisions
program was officially launched in standard 747-400 as optional, higher
to support increased maximum
November 2000 with an order from thrust engines.)
takeoff weight.
Qantas Airways for six passenger With the same shape as standard
airplanes. Formal design of the 747-400s, Longer Range 747-400s 2. Flight deck enhancements.
747-400ER began that same month. are able to use the same airport
3. New auxiliary fuel system on
The first 747-400ER rollout was in gates and can operate on the
the 747-400ER.
June 2002, and Qantas took first same runways and taxiways. The
delivery in October 2002. derivatives use the same pool of 4. New interior on 747-400ER.

20 AERO First-Quarter 2003 — January

 Liquid crystal displays.
The six cathode ray tube (CRT)
displays on the standard 747- 400 flight
deck have been replaced with liquid
crystal displays (LCD) identical to
those on the 767- 400. Compared
with CRT displays, LCDs weigh less,
generate less heat, and have a longer
mean time between failures. LCDs
are able to display more information
than CRT displays and are required
on the 747- 400ER to present the addi-
tional synoptics for the auxiliary fuel
tank. The LCDs are line replaceable
and can be intermixed with the 747- 400
CRT displays, thereby reducing the
cost of spares.
Integrated standby flight display.
Today’s 747- 400 flight decks include
three standby displays — an attitude
SYSTEMS AND STRUCTURAL ■ The wing box skins were thickened, display, an airspeed display, and an
1 REVISIONS TO SUPPORT and the leading edge and trailing altimeter. On the 747- 400ER and
INCREASED MAXIMUM edge flaps and flap drive systems 747- 400ER Freighter, those three
TAKEOFF WEIGHT were strengthened. displays are combined into one LCD,
The 747- 400ER and 747- 400ER ■ The landing gear and supporting the integrated standby flight display
Freighter both have a maximum takeoff structure were redesigned and larger, (ISFD). (The ISFD currently is an option
weight of 910,000 lb (412,770 kg), 50-in radial tires and wheels were on 747- 400s but is expected to become
which is 35,000 lb (15,785 kg) greater installed. standard late in 2003.) The ISFD has
than that of the standard 747- 400. the same look as the primary flight dis-
■ To accommodate those tires and to
747-400ER. With a greater maxi- play, which is the primary situational
provide sufficient room to retract the
mum takeoff weight than the standard display. This similarity makes it easier
wheels, the shape of the landing gear
747- 400, the 747- 400ER can fly for the crew to transition to the ISFD
doors was modified.
7,670 nmi — approximately 410 nmi in the unlikely event that all main flight
farther — or carry an extra 15,000 lb ■ The systems located in the wheel displays malfunction. The ISFD also
(6,803 kg) of payload, either as extra wells were rerouted to protect weighs less and has a significantly longer
cargo or passengers (fig. 1). against larger burst tire volumes. life than its mechanical predecessors.
747-400ER Freighter. The standard ■ The Halon fire suppression system Reduced flight deck noise.
747- 400 Freighter can carry 248,000 lb bottles were enlarged and relocated On the 747- 400ER and 747- 400ER
(103,419 kg) of cargo approximately along the side of the aft cargo Freighter, sound-damping insulation
4,450 nmi. With the 747- 400ER compartment. blankets in the overhead area of the
Freighter, operators can fly an addi-
flight deck reduce ambient noise. (All
tional 525 nmi or carry an additional
22,000 lb (9,979 kg) of payload. The
2 FLIGHT DECK ENHANCEMENTS subsequent 747s will contain the blan-
kets.) During flight tests, the blankets
improvements to the 747- 400ER
The 747- 400ER and 747- 400ER reduced overhead noise levels by more
Freighter provide additional operational
Freighter flight deck was enhanced to than 2 dBa. An optional treatment for
flexibility (fig. 2).
incorporate systems changes and flight deck windows two and three
Systems and structural changes were
accommodate new operating limits. reduces ambient noise by an additional
made to support the increase in takeoff
Most notably, software for the flight 1.5 dBa. When these two features are
weight.
management computer, central mainte- combined, the flight deck noise of the
■ In areas where loads increased, the nance computer, and weight and bal- 747- 400ER and 747- 400ER Freighter
body and empennage were strength- ance system was upgraded to include is comparable to that of the quietest
ened by increasing the thickness of the weight and performance data for the widebody jets now in production or
skins, stringers, frames, and bulkheads. new derivatives. planned for the future.

First-Quarter 2003 — January AERO 21

 1 747-400ER INCREASES PAYLOAD AND RANGE
FIGURE

(80) 180
747-400
160 875,000-lb (396,900-kg) MTOW
(70)

140
(60) 410 nmi additional range or
Payload, 1,000 lb (1,000 kg)

120 15,000 lb (6,803 kg) additional payload

(50) 747-400ER*
100 910,000-lb (412,770-kg)
416 passengers MTOW
(40)
80
747-400ER**
(30) 910,000-lb (412,770-kg)
60 Fuel capacity, U.S. gal (L) MTOW
(20) 63,545 (240,537) *One body tank
40 installed
60,305 (228,272)
Three-class seating
(10) Typical mission rules 57,065 (216,008) **Two body tanks
20 installed

0 0
1 2 3 4 5 6 7 8 9 10 11
(0) (5) (10) (15)
Range, 1,000 nmi (1,000 km)

2 747-400ER FREIGHTER INCREASES PAYLOAD AND RANGE

FIGURE

700 MZFW 635,000 lb (288,040 kg)

(120) MLW limit Optional MZFW/MLW
611,000 lb (277,145 kg)
747-400F
600 610,000 lb (276,700 kg) 875,000-lb (396,900-kg) MTOW
(100)
525 nmi additional range or 747-400ERF
500
Payload, 1,000 lb (1,000 kg)

22,000 lb (9,979 kg) additional payload 910,000-lb (412,770-kg)

(80) MTOW
400

(60)
300

(40)
200 Typical mission rules
Tare weight included in operating empty weight Fuel capacity, U.S. gal (L)
53,765 (203,500)
(20)
100

(0) 0
0 1 2 3 4 5 6 7 8 9
(0) (4) (8) (12) (16)
Range, 1,000 nmi (1,000 km)
22 AERO First-Quarter 2003 — January
 3 NEW AUXILIARY FUEL SYSTEM 3 SINGLE AUXILIARY TANK FUEL CELL
ON THE 747-400ER FIGURE

One of the most significant differences

between the standard 747- 400 and the
747- 400ER is the auxiliary fuel system,
which is available with one fuel cell or
two. (The auxiliary fuel system is not
used on the 747- 400ER Freighter.) The
747- 400ER is configured with a single
fuel cell, which accommodates an
additional 3,210 gal (12,151 L) of fuel
when compared with the 747-400.
Structural and systems provisions are
provided for a second fuel cell, which
can be ordered as an option or installed
later. The one- and two-cell installations
look like and are managed as a single
auxiliary tank (fig. 3).
The auxiliary tank is located in the
lower lobe, immediately in front of the
center wing tank, where cargo contain-
ers usually are carried. To accommodate The body structure in this zone was blower. A switch for the auxiliary tank
the auxiliary fuel tank, the potable completely redesigned to protect the transfer valves has been added to the
water system was moved to the aft end auxiliary tank from damage in the event fuel management area of the pilot’s
of the aft cargo compartment, and the of an emergency such as a wheels-up overhead panel, which allows the crew
size of the forward cargo compartment landing. Existing sheet-metal frames to operate the fuel tank manually.
was reduced. Whenever possible, were replaced with single-piece Because the new tank is fully integrated
common fuel systems components machined frames. To ensure adequate into and operates seamlessly with the
were used. strength for decompression, a higher existing fuel system, there is no
The fuel cell suspension system strength material is used for the chords increase to the flight crew’s workload.
and attaching structure were designed of the main deck floor beams. To Although auxiliary fuel systems
to allow for quick installation. The cells minimize the possibility of fuel cell that use air pressure to transfer fuel
are installed or removed with a special damage in the event of a burst engine have been used before on Boeing and
tool rolled in and out on the cargo rotor, a titanium shield is installed on other airplanes, this is the first such
system rollers. Fuel cells and compo- the forward body and wing ribs. system designed by Boeing
nents are readily accessible — without The auxiliary tank is segregated from Commercial Airplanes.
removing the cells from the airplane — the cargo compartment by a structural
NEW INTERIOR ON THE
through line replaceable units mounted cargo barrier and cargo liners. The tank 4 747-400ER
on the front panel and walkways to the and its immediate environment were
right of and between the cells. designed to keep the tank within struc- From the passenger perspective,
The fuel cells are constructed from tural temperature and fuel temperature perhaps the most notable change is the
double-walled aluminum honeycomb limits in the rare event of a cargo fire. updated interior of the 747- 400ER.
panels that are reinforced and stiffened During flight, fuel is used first The award-winning Boeing signature
with a metallic secondary structure. from the center fuel tank. As the flight interior, first developed for the 777,
Fuel cells are protected from shifting progresses, fuel is transferred from the is distinguished by curved architecture
cargo by a barrier attached to the front auxiliary tank to the center tank using and a brighter color scheme than on
side of the forward-most auxiliary air pressure provided by one of two the standard 747- 400. The new interior
fuel cell. The fuel tank is suspended independent sources. The primary source has a blended ceiling and bin line and
5 in above the cargo floor and 4 in is cabin air pressure. The secondary pivot bins that provide approximately
below the cargo ceiling and is isolated source, which is used at low altitudes or 30 percent more space for roll-aboard
from normal airplane deflections when the airplane is on the ground luggage than the standard 747- 400.
by a six-point suspension system (during fuel jettison or on-the-ground The new bins and bin line offer more
anchored with titanium fittings. defueling), is an electrically powered passenger headroom, afford better

First-Quarter 2003 — January AERO 23

access to luggage, and hold stowed lug- pump. After each flight, the system differs significantly, making it cumber-
gage in place more securely. The upper toggles from one pump to the other. some to modify the interior layout after
deck of the 747-400ER also has twice This distributes operating hours delivery. All 747-400ERs equipped
the stowage capacity of standard between the pumps and provides a with an IFE system include the new
747-400s. (Boeing is considering whe- backup if one pump fails on the ground IFE interface backbone wiring, making
ther to offer this new interior on future or during flight. it easier, quicker, and more efficient
747-400s and as part of a retrofit for A quick-charge emergency lighting to change the interior layout. (All sub-
standard 747-400s already in service.) battery replaces the trickle-charge sequent 747-400 passenger airplanes
During the design process, each battery. The new battery weighs less, is will include the new wiring.)
interior system was evaluated for relia- slightly less expensive, and has a longer
bility and maintenance costs. System life expectancy, which makes it more SUMMARY
enhancements include the following. economical. More significant, the
An electrically activated passenger quick-charge battery can be recharged The 747-400 ER and
oxygen system replaces the passenger in approximately 1 hr, compared with 747-400ER Freighter — the
oxygen system on the 747-400. The 8 to 10 hr for the trickle-charge battery.
newest derivatives of the 747
new system, which uses many com- This difference allows operators to
ponents developed for the 777, is easier return airplanes to service much more family—are unique in their
to rig and maintain than the system on quickly after using, maintaining, or classes. Features include
the 747-400. testing emergency lighting. a maximum takeoff weight of
A two-pump potable water system Light-emitting-diode–illuminated 910,000 lb, which makes it
replaces the pressurized potable water sign packs replace incandescent bulb possible to fly farther or carry
system on the standard 747-400. On the information sign packs. The new signs
more payload, and an enhanced
747-400, the system is located in the are brighter, are similarly priced, and
forward cargo hold. Because this space have a significantly longer life expec- flight deck that offers new
is occupied by the auxiliary fuel tank tancy, which translates into less main- LCDs, a new ISFD, and addi-
on the 747-400ER, a new potable water tenance and lower maintenance costs. tional insulation to reduce noise.
tank was designed and located in the New backbone wiring for the in- The 747-400ER also has a
bulk cargo area. This tank is fitted flight entertainment interface, which new auxiliary fuel system,
with a two-pump water delivery system, will accommodate any interior layout. available with one fuel cell or
similar to that on the 777. The two- Because each airline has a different
pump system increases dispatch relia- interior layout with different in-flight
two; a newly designed interior;
bility; if one pump fails, the system entertainment (IFE) equipment, the and enhanced interior systems.
switches automatically to the functional wiring for each IFE installation also

About the Author

Kurt Kraft
has held engineering and leadership positions on a variety of
Boeing propulsion and airplane programs since 1979, including
747 Airplane Level Integration Team (ALIT) leader, 767-400
Propulsion Platform team leader, and Propulsion chief engineer
for the 737/757 Programs.

24 AERO First-Quarter 2003 — January

 TECHNICAL CHARACTERISTICS OF THE 747-400 AND 747-400ER
747-400 747-400ER

Seating (typical three-class configuration) 416 416

Maximum takeoff weight 875,000 lb (396,900 kg) 910,000 lb (412,770 kg)

Maximum landing weight 652,000 lb (295,740 kg) 652,000 lb (295,740 kg)

Range:
Statute miles 8,360 miles 8,830 miles
7,260 nmi 7,670 nmi
13,445 km 14,205 km

Los Angeles–Hong Kong New York–Hong Kong

City pairs Los Angeles–Sydney Los Angeles–Melbourne
Singapore–London Rio de Janeiro–Perth

Cruise speed at 35,000 ft Mach 0.855 Mach 0.855

567 mi/h (912 km/h) 567 mi/h (912 km/h)

Pratt & Whitney 4062 Pratt & Whitney 4062

63,300 lb (28,710 kg) 63,300 lb (28,710 kg)
Engines: Rolls-Royce RB211-524H2-T Rolls-Royce RB211-524H2-T
maximum thrust 59,500 lb (26,990 kg) 59,500 lb (26,990 kg)
General Electric CF6-80C2B5F General Electric CF6-80C2B5F
62,100 lb (28,165 kg) 62,100 lb (28,165 kg)

Maximum fuel capacity 57,285 U.S. gal (216,840 L) 63,705 U.S. gal (241,140 L)*

Length 231 ft 10 in (70.6 m) 231 ft 10 in (70.6 m)

Wingspan 211 ft 5 in (64.4 m) 211 ft 5 in (64.4 m)

Tail height 63 ft 8 in (19.4 m) 63 ft 8 in (19.4 m)

6,025 ft3 (170.5 m3) 5,599 ft3 (158.6 m3)

Cargo volume
or 5,332 ft3 (151 m3)** or 4,837 ft3 (137 m3)***

Exterior diameter 21 ft 3.5 in (6.5 m) 21 ft 3.5 in (6.5 m)

Interior cross-section width 20 ft 1.5 in (6.1 m) 20 ft 1.5 in (6.1 m)

*With two auxiliary body fuel tanks in the forward lower cargo hold. The fuel capacity with one body tank is 60,495 U.S. gal (228,990 L).

**6,025 ft3 (170.5 m3) = 30 LD-1 containers + bulk; 5,332 ft3 (151 m3) = five pallets, 14 LD-1 containers + bulk (one pallet = 96 in x 125 in, 244 cm x 318 cm).

***5,599 ft3 (158.6 m3) = 28 LD-1 containers + bulk; 4,837 ft3 (137 m3) = four pallets, 14 LD-1 containers + bulk (one pallet = 96 in x 125 in, 244 cm x 318 cm).
These volumes are reduced relative to the 747-400 because of the addition of one body fuel tank, basic on the 747-400ER, in the forward lower cargo hold.

First-Quarter 2003 — January AERO 25

Quiet Climb
Boeing has developed the Quiet Climb System, an automated avionics feature
for quiet procedures that involve thrust cutback after takeoff. By reducing
and restoring thrust automatically, the system lessens crew workload and
results in a consistently quiet footprint, which helps airlines comply with
restrictions and may allow for an increase in takeoff payload.
26 AERO First-Quarter 2003 — January
 ADVANCED

AVIONICS

FOR

System QUIET

OPERATIONS

JERRY FRIEDRICH DANIEL M C GREGOR DOUGLAS WEIGOLD

AVIONICS DESIGN ENGINEER AIRPORT AND COMMUNITY NOISE ENGINEER AERODYNAMIC PERFORMANCE ENGINEER
NAVIGATION/GUIDANCE/THRUST MANAGEMENT COMMUNITY NOISE AIRPLANE PERFORMANCE & PROPULSION
BOEING COMMERCIAL AIRPLANES BOEING COMMERCIAL AIRPLANES BOEING COMMERCIAL AIRPLANES

TECHNOLOGY/PRODUCT DEVELOPMENT
First-Quarter 2003 — January AERO 27
W
ith higher density popula- the cutback altitude. This article Cutback altitude.
tions surrounding airports discusses The advisory circular also specifies
that the minimum altitude at which the
throughout the world, 1. FAA advisory guidelines. thrust can be reduced, or cut back, is
the sound of airplanes has become 800 ft above ground level (AGL).
2. The Boeing QCS.
an issue of increasing importance in
3. Basics of sound measurements.
recent years. Noise-abatement require- 2 THE BOEING QCS
ments and procedures imposed by 4. Effect of the Boeing QCS on
local airport authorities have affected sound in communities. Boeing developed the QCS, an
airline operations in many ways, advanced avionics feature, to directly
assist flight crews in flying the quiet
resulting in restricted hours of departure profiles defined in the
operation, required weight offloads, 1 FAA ADVISORY GUIDELINES advisory circular. The QCS controls
fines, and surcharges. thrust reduction and restoration
Airplane and engine manufacturers In 1993, the FAA issued advisory automatically, thereby eliminating
circular AC91-53A, “Noise Abatement the need for manual control and
have been successful in producing
Departure Profiles,” which standardizes ensuring consistency.
quieter airplanes, but more stringent procedures by defining acceptable During the takeoff checklist pro-
noise-abatement requirements and criteria for speed and minimums for cedure, the pilot selects the QCS and
the high cost of engine modification thrust cutback settings and altitudes for enters the altitudes at which thrust
have prompted the industry to con- various airplane takeoff configurations. should be reduced (≥800 ft AGL) and
sider additional ways to decrease restored. With the autothrottle system
Minimum thrust cutback.
engaged, the QCS reduces engine
airplane sound in communities. The minimum thrust cutback represents
thrust when the cutback altitude is
One alternative is a maneuver in the minimum level of thrust that would reached to maintain the optimal climb
which the flight crew takes off with ensure a sufficient climb gradient if an angle and airspeed. When the airplane
engine were to fail. This thrust value is reaches the chosen thrust restoration
full takeoff power, climbs rapidly,
determined by the number of engines altitude (typically 3,000 ft AGL), the
and then cuts the thrust manually to on the airplane. On a two-engine QCS restores full climb thrust auto-
a predetermined value at a specified airplane, the minimum thrust cutback matically. As such, QCS reduces pilot
cutback altitude. The airplane con- ensures an engine-inoperative climb workload during a phase of flight that
tinues to climb, albeit at a much gradient of 1.2 percent. If one engine already is task intensive.
slower rate, until it is high enough fails after cutback, the thrust from the QCS incorporates multiple safety
operating engine must maintain a climb features and will continue to operate
that sound in the community is not gradient of at least 1.2 percent. On even with system failures. If a system
an issue. The crew then adds more three-engine and four-engine airplanes, failure does occur, there are several
power to continue flight. the minimum thrust cutbacks are methods for exiting QCS. In the most
One potential problem with this engine-inoperative climb gradients of common method, the pilot selects
maneuver is that the pilot must cut 1.5 percent and 1.7 percent, respectively. the takeoff/go-around switches on the
back and restore engine thrust manu- Zero percent gradient cutback. throttle control stand. The pilot can take
Under certain conditions, the advisory control of the throttles easily by discon-
ally at the correct altitudes. The Boeing
circular also allows a thrust cutback necting the autothrottle and controlling
Quiet Climb System (QCS), which is the thrust manually, as appropriate.
that maintains a zero percent engine-
selected during the takeoff procedure,
inoperative climb gradient. This type QCS availability.
automatically reduces and restores of cutback is permitted for airplanes The QCS is available on all 737-600/
engine thrust at the specified altitudes, with avionics systems that can detect -700/-800/-900 airplanes and pro-
thereby reducing pilot workload. engine failure and automatically vides an automatic thrust cutback
In an effort to standardize noise- increase the thrust on the remaining engine-inoperative climb gradient of
abatement procedures, the Federal engine or engines to a value that 1.2 percent. The zero percent climb
maintains the minimum climb gradient. gradient QCS is scheduled to become
Aviation Administration (FAA)
These minimum climb gradients are available in first-quarter 2003 on
has issued advisory guidelines that 1.2 percent on a two-engine airplane, the 737-600/-700/-800/-900. Boeing
define departure profiles, including 1.5 percent on a three-engine airplane, also is considering the QCS for the
the minimum thrust required and and 1.7 percent on a four-engine airplane. 747-400, which would have an

28 AERO First-Quarter 2003 — January

automatic thrust cutback engine- 1 FLYOVER SOUND IN A-WEIGHTED DECIBELS
inoperative climb gradient of 1.7 percent. FIGURE

Other Boeing systems. Airplane flying over monitor

A system similar to the QCS is avail- Peak dBA
able on the MD-90 series. That system, Airplane approaching monitor
however, requires that the pilot calcu- Thrust cutback Airplane leaving monitor
late the necessary thrust and then enter Incremental
it manually for automatic thrust cutback noise measurements

Sound level, dBA

during takeoff. The 757 also has an
option similar to QCS that provides
an engine-inoperative climb gradient
of 1.2 percent. To be activated, the
crew must select the system manually
at the cutback altitude.
Monitor
BASICS OF SOUND
3 MEASUREMENTS Time

Airplane sound is measured along

the flight path using monitors located
near the ground. The level measured 2 FLYOVER SOUND IN TIME-INTEGRATED MEASUREMENT
by each monitor is a function of the FIGURE

airplane, engine type, altitude, and

thrust. An airplane event consists Airplane flying over monitor
of a single flyover with incremental
Airplane approaching monitor Airplane leaving monitor
measurements recorded by the
monitors (fig. 1). A time history, Thrust cutback
which is a composite of the individual
measurements, shows changes in
Sound level, dBA

the sound level over time. The history

provides information on the maxi- Sum of total energy
mum (peak) level and the duration (single-event noise-exposure level) 65 dBA
of the event.
Three common ways Monitor
of representing sound.
One common way to represent airplane Time
sound uses peak A-weighted decibels
(typically referred to as peak dBA), heavy fuel and passenger payloads, the
London Heathrow Airport.
which are decibels adjusted for how lower two limits are difficult to meet.
London Heathrow Airport, in the
the human ear hears sound (fig. 1).
United Kingdom, is one of the world’s
Another way to represent sound is John Wayne Airport.
most heavily regulated airports. It has John Wayne Airport, in Orange
time-integrated measurement (fig. 2).
With this method, individual measure- four departure runways for commercial County, California, is another of the
ments of energy taken over time are airplanes and 10 sound monitors. To most heavily regulated airports. The
summed. regulate airplane noise and its impact airport has one departure runway for
A third way to represent airplane on local communities, the airport has commercial airplanes and seven moni-
sound uses a contour, or footprint. A established peak dBA noise limits for tors. Airplane sound is measured using
footprint shows the impact of sound daytime, shoulder period, and night- a single-event noise-exposure level
on communities near the airport and time operations. The daytime (7 a.m. to (SENEL), which is a type of time-
provides information about how vari- 11 p.m.) limit is 94 dBA; the shoulder integrated measurement. The SENEL
ables such as airplane configuration, period (11 p.m. to 11:30 p.m. and also uses dBA time history, but rather
flight procedures, and new airplane 6 a.m. to 7 a.m.) limit is 89 dBA; the than reporting only the peak dBA, the
technology (e.g., QCS) affect the size nighttime (11:30 p.m. to 7 a.m.) limit energy of all sound levels >65 dBA
and shape of the footprint (fig. 3). is 87 dBA. For long-haul carriers with is added to produce a single value.
First-Quarter 2003 — January AERO 29
 3 THE BOEING QCS
FIGURE

25,000 ft
75 dBA sound contour levels
Without QCS.
20,000 ft Thrust cutback to
maximum climb power.
Baseline footprint.
15,000 ft
QCS with thrust cutback to
maintain engine-inoperative
10,000 ft
climb gradient of 1.2%.
Footprint area reduced by 14%.
4,400 ft 5,000 ft
QCS with thrust cutback to maintain
engine-inoperative climb gradient of 0%.
0 ft Footprint area reduced by 21%.
Distance from brake release

-5,000 ft Source: The Boeing Company

EFFECT OF THE BOEING QCS benefit of allowing airplanes to carry airplanes without QCS. The zero per-
4 ON SOUND IN COMMUNITIES more passengers, cargo, or fuel. cent climb gradient QCS would lower
the SENEL by an additional 1 dB at
The QCS reduces takeoff sound by The Quiet 737-800. the same payload.
reducing thrust, which helps airlines On current-production 737-800s with
comply with noise restrictions that carry CFM International CFM56-7B26 A Quieter 747-400.
increasingly severe economic penalties engines, the QCS reduces the acoustic Approximately 90 percent of the
for violations. At John Wayne Airport, footprint by 14 percent. On these 747-400s operating out of London
for instance, fines can be as much as airplanes, the zero percent climb gra- Heathrow Airport could be quieter by
$500,000. To avoid such penalties, air- dient QCS is expected to reduce the slightly more than 1 dBA if they were
lines that use a manual procedure to cut acoustic footprint by 21 percent. At equipped with the 1.7 percent QCS.
back and restore thrust during takeoff John Wayne Airport monitor three (the The reduction would be even more
often reduce takeoff weight to ensure most critical monitor for the 737-800), significant for airplanes with lower
that sound levels stay within designated a typical departure with the 1.2 percent takeoff weights. Alternatively, with the
limits. Because the QCS standardizes climb gradient QCS would lower the QCS, 75 percent of the 747-400s de-
the noise-abatement maneuver, the SENEL by ~3.2 dB. This improvement parting from Heathrow could increase
system minimizes the need to reduce would permit an ~5,500-lb increase their takeoff weight by an additional
takeoff weight. This, in turn, provides in payload with the same sound level 25,000 lb and be as quiet at the moni-
airlines with the added economic registered at takeoff as on similar tors as similar airplanes without QCS.

30 AERO First-Quarter 2003 — January

 Jerry Friedrich
has been with Boeing for
15 years and is an avionics
About the Authors design engineer and a
Designated Engineering
Representative in the thrust
management/autothrottle
group that supports 737, 757,
767, and 777 airframes.

Daniel McGregor
has been with Boeing since
1985 and has extensive experience
developing prediction applications
that support airplane certification,
community noise research, and
interior noise. He is a lead engi-
neer in Noise and Emissions and
develops operational procedures
SUMMARY to reduce the impact of airplanes
in communities. He also is leader
In response to increasingly stringent of the Boeing John Wayne Airport
noise regulations and customer need, Air Carrier support team, which
Boeing has developed the QCS, an has streamlined airport review
advanced avionics systems feature and qualification requirements
that reduces pilot workload during the resulting in cost savings for
labor-intensive period of takeoff while airlines and John Wayne Airport.
helping airlines meet requirements
without incurring penalties. The QCS
automatically moves the throttle
controls and retards engine thrust to
maintain an optimal climb angle and Douglas Weigold
airspeed, thereby reducing sound in is a 14-year veteran of the
the community and minimizing the aerospace industry and has
impact on communities near an air- worked on airplane programs
port. An airplane equipped with the that include Longer Range
QCS may be able to carry more cargo, 777, 717, MD-11, and High
fuel, or passengers and still be quiet. Speed Civil Transport. As part
The QCS currently is available on of the Production and Fleet
737-600/-700/-800/-900 airplanes Support Aerodynamics group,
and is being considered for use on he currently works on narrow-
747-400s. Some other Boeing models body performance issues and
have systems similar to QCS. is group noise focal for all
airplane models.

First-Quarter 2003 — January AERO 31

Boeing Commercial Airplanes
FIELD SERVICE REPRESENTATIVES
LOCATION REPRESENTATIVE TELEPHONE

If your Boeing Field Service Region 1 Director D. Wall 305-864-8330 Region 4

representative cannot be reached, Eastern Atlanta (CQT) W. Ellis 404-530-8674 Northern
support is available at the United States/ Atlanta (DAL) F. Piasecki 404-714-3129 Europe/
following numbers 24 hours a day: Latin and South Bogota H. Sandova 57-1-413-8218/8128 Tel Aviv
America Buenos Aires (ARG) M. Snover 54-11-4778-3250
Rapid Response Center Charlotte T. Price 704-359-2049
Boeing-designed airplanes: Mexico City (AMX) M. Vanover 525-133-5288/5289
Phone 206-544-7555 Mexico City (CMA) H. Connolly 525-762-0167
Fax 253-773-6606 Miami R. Larson 786-265-8288
New York M. Murbach 718-995-9707
Orlando D. Pemble 407-251-5906
Technical Support Desk Panama City S. Frimer 507-238-4296 x4366
Douglas-designed airplanes: Pittsburgh R. Lehnherr 412-472-7277/7279
Phone 562-497-5801 Port of Spain L. Richardson 868-669-0491
Fax 206-544-0641 Rio de Janeiro J. Bartashy 55-21-393-8343
Santiago R. Farnsworth 56-2-601-0171
Sao Paulo L. Anglin 55-11-532-4852/4028
Spares orders/quotes: Region 5
206-662-7141 (Information) Region 2 Director G. Norden 415-864-7970 Central and
206-662-7200 (Spares AOG) Western Calgary J. Fitzhum 403-221-4858 Southern
562-593-4226 (Douglas AOG) United States/ Honolulu (ALO) A. McEntire 808-836-7472 Europe
Canada Honolulu (HWI) R. Owens 808-838-0132
Indianapolis (AAT) T. Bryan 317-282-5700
Indianapolis (UAL) R. Webb 317-757-2299
Las Vegas S. Gorski 702-944-2908
Long Beach D. Miles 562-528-7248
Contact your region’s Boeing Minneapolis C. Barrea 612-726-2691
Customer Support vice president Montreal T. Morris 514-422-6100/6839/6840
to facilitate support in the areas Oakland K. Standerfer 510-562-8407
of flight services, maintenance Phoenix S. Stillwell 480-693-7074/7075/7179
services, spares, training, and San Francisco J. Russell 650-877-0181
technical services and modifications. Santa Barbara (BBJ) S. Lenicka 805-886-9833
Seattle/Tacoma D. Inderbitzen 206-431-3763/3764/7273
The Americas Vancouver D. Bays 604-270-5351/276-3739
Tom Basacchi
Phone 206-766-1121 Region 3 Director D. Krug 817-358-0081
Fax 206-766-2205 Chicago (AAL) L. Kuhn 773-686-7433
Region 6
Central
E-mail thomas.l.basacchi@boeing.com Columbus (BBJ) D. Kopf 614-239-2461
Middle East/
United States
Dallas (AAL) C. Fox 972-425-6206
Africa/Asia
Asia-Pacific Dallas (DAL) D. Root 972-615-4539
Bruce Dennis Dallas (Love Field) R. Peterson 214-792-5862/5887/5911
Phone 206-766-2309 Fort Worth C. Paramore 817-224-0560/0561/0564
Fax 206-766-1520 Houston C. Anderson 713-324-3611
E-mail bruce.c.dennis@boeing.com Houston (Hobby) D. Hendrickson 713-324-4192
Kansas City J. Connell 816-891-4441
Europe Louisville A. Andrus 502-359-7679
Daniel da Silva Memphis D. Schremp 901-224-5087
Phone 206-766-2248 Milwaukee T. Plant TBD
Fax 425-237-1706 Orlando (BBJ) F. Gardiner 407-877-4030
E-mail daniel.c.dasilva@boeing.com Tulsa J. Roscoe 918-292-2404/2707
Wilmington G. Johnson 937-382-5591 x2736
Middle East, Africa, Russia, and
South Asia-Pacific
Marty Bentrott
Phone 206-766-1061
Fax 206-766-1339
E-mail martin.a.bentrott@boeing.com
2 4 - H O U R A I R L I N E S U P P O R T

LOCATION REPRESENTATIVE TELEPHONE LOCATION REPRESENTATIVE TELEPHONE

Director E. Berthiaume 44-20-8235-5600 Region 7 Director R. Nova 65-6732-9435/9436/9437

Copenhagen A. Novasio 45-3-232-4373 Southeast Bangkok D. Chau 66-2-531-2274
Dublin C. Lohse 353-1-886-3086/3087 Asia Jakarta R. Tessin 62-21-550-1614/1020
Gatwick B. Minnehan 44-1293-510-465 Kuala Lumpur M. Standbridge 60-3-746-2569
Helsinki D. Laws 358-9-818-6450 Manila D. Lucas 63-2-852-3273
London G. Van de Ven 44-20-8562-3151 Singapore A. Hagen 65-541-6075
Luton (BRI) B. Dubowsky 44-1582-428-077 Taipei (CHI) M. Heit 886-3-383-3023
Luton (EZY) R. Adams 44-1582-525-869 Taipei (EVA) D. Bizar 886-3-393-1040
Manchester J. Raispis 44-1-612-326-693
Region 8 Director T. Premselaar 81-3-3747-0073/0078
Oslo A. Holin 47-6481-6598/6613
Asia/ Auckland R. Lowry 64-9-256-3981
Stansted D. Johnson 44-1279-825638
Australia/ Brisbane D. Bankson 61-7-3295-3139
Stansted (RYR) J. McMahon 44-1279-666263
New Zealand Ho Chi Minh J. Baker 84-4-934-2342
Stavanger E. Fales 47-51-659-345
Melbourne E. Root 61-3-9280-7296/7297
Stockholm G. Ostlund 46-8-797-4911
Nadi (SPBOG) H. Kirkland TBD
Tel Aviv J. Sveinsson 972-3-9711147 Narita A. Gayer 81-476-33-0606
Okinawa E. Sadvar 81-988-57-9216
Director G. Gebara 216-1-788-472 Pusan K. Cummings 82-51-325-4144
Algiers T. Alusi 213-21-509-378 Seoul (AAR) J. DeHaven 82-2-665-4095
Amsterdam (KLM) B. Balachander 31-20-649-8100 Seoul (KAL) G. Small 82-2-663-6540
Amsterdam (TAV) H. Schuettke 31-20-648-4639 Sydney (IMU) B. Payne 61-2-9317-5076 x419
Athens B. Oani 30-1-353-6317 Sydney (QAN) W. Mahan 61-2-9691-7418
Brussels I. Gilliam 32-2-7234822 Tokyo (ANA) T. Gaffney 81-3-5756-5077/5078
Casablanca M. Casebeer 212-2-53-94-97 Tokyo (JAL) L. Denman 81-3-3747-0085/3977
Geneva (BBJ) D. Stubbs 41-22-700-2159/2654 Tokyo (JAS) R. Saga 81-3-5756-8737
Lanarca S. Mura 35-7-4815700
Luxembourg J. Erickson 352-4211-3399 Region 9 Director T. Lane 86-10-6539-2299 x1038
Madrid H. Morris 34-91-329-1755 China Beijing R. Shafii 86-10-6456-1567
Palma (de Mallorca) C. Greene 34-971-789-782 Chengdu G. King 86-28-570-4278
Paris (CDG) M. Hamilton 33-1-4862-7573/4192 Guangzhou S. Sherman 86-20-8659-7994
Paris (ORY) L. Wennergren 33-1-4686-1047 Haikou R. Wiggenhorn 86-898-575-6734
Rome J. Hill 39-06-6501-0135 Hong Kong R. Brown 852-2-747-8945/8946
Jinan P. Lavoie 86-531-899-4643
Tunis D. Marble 216-1-781-996
Kunming T. Bray 86-871-717-5270
Zurich K. Goellner 41-1-812-6816/7414
Shanghai (CEA) M. Perrett 86-21-6268-6268 x35156
Shanghai (SHA) D. Babcock 86-21-6268-6804
Director C. Armstrong 971-4-299-5412
Shenyang L. Poston 86-24-8939-2736
Addis Ababa J. Wallace 251-1-610-566 Shenzhen S. Cole 86-755-777-7602
Almaty R. Anderson 7-300-722-3312 Urumqi D. Cannon 86-991-380-1222
Ashgabat J. McBroom 993-12-510-589 Wuhan M. Nolan 86-27-8581-8528
Cairo M. McPherson 20-2-418-3680 Xiamen Y. Liu 86-592-573-9225
Dammam R. Cole 966-3-877-4652 Ulaan Baatar P. Kizer 976-9911-0471
Dubai G. Youngblood 971-4-208-5656
Istanbul B. Nelson 90-212-573-8709/663-1203 Region 10 Director T. Waibel 49-89-236-8060
Jeddah (SRF) L. Giordano 966-2-684-1184 Eastern Berlin (BER) F. Wiest 49-30-4101-3868
Jeddah (SVA) A. Noon 966-2-685-5011/5013 Europe/ Berlin (GER) R. Lopes 49-30-4101-3895
Johannesburg A. Ornik 27-11-390-1130/1131 Russia Bucharest S. Oakes TBD
Mumbai R. Piotrowski 91-22-615-7179/7777 x3289 Budapest R. Horton 36-1-296-6828
Muscat A. Ostadazim 968-519467 Frankfurt (DLH) J. Harle 49-69-696-89407
Nairobi R. Aman 254-2-824659 Hamburg P. Creighton 49-40-5070-3040/3630
Riyadh (BBJ) J. Richards 966-1-461-0607 Hanover R. Anderson 49-511-972-7387
Sanaa F. Fujimaki 967-1-346-125 Kiev R. South 380-44-230-0017
Tashkent R. Webb 998-71-1206572 Moscow (ARO) V. Solomonov 7-095-961-3819
Moscow (TRX) E. Vlassov 7-095-937-3540
Prague M. Coffin 42-02-2056-2648
Vienna L. Rahimane 43-1-7000-75010
Warsaw F. Niewiadomski 48-3912-1370