GNSS loss and GNSS Interference on Airbus A/C

Reference: 34.36.00049 Issue date: 17-NOV-2023 Last check date: 17-NOV-2023 Status: Open
A/C type/serie: A300, A300-600, A310, A318, A319, ... ATA: 34-36
Engine manufacturer: Supplier:
Purpose / Reason for revision: Table of contents added. Operational Considerations updated.
Engineering Support Status: Open
Revision updates are highlighted in bold blue.

TABLE OF CONTENTS:

0. Error! Reference source not found.

1. Error! Reference source not found.
1.1 Error! Reference source not found.
1.1.1 Error! Reference source not found.
1.1.2 Error! Reference source not found.
1.1.3 Error! Reference source not found.
1.1.4 A350
1.2
Summary of functional and system effects
1.2.1 Navigation
1.2.2 Surveillance
1.2.3 Communication
1.3 Related WISE articles
2. Operational considerations
2.1 FCOM procedures and reporting
2.2 Undue TAWS alerts
3. Maintenance Recommendations
3.1 CASE 1 – Transient symptoms observed when A/C overflies a known GNSS RFI area
3.2 CASE 2 – Transient symptoms observed in an area not known for GPS interference
3.3 CASE 3 – Effects during GPS interference exposure not covered in chapter 1 or events requiring further analysis
4. Glossary

0. BACKGROUND

On most of Airbus aircraft, Global Navigation Satellite System (GNSS1) signals are one of the main inputs used for aircraft positioning and time reference for on-board Communication,
Navigation and Surveillance functions. The Airbus aircraft installations are compliant with applicable regulations and recommended practices on aeronautical usage of GNSS for Communication,
Navigation and Surveillance applications.

Performance (accuracy, integrity, availability and continuity) of the aircraft positioning highly relies on the external GNSS signals. A degradation of the external GNSS signals due to external
or internal Radio Frequency Interferences (also known as “GNSS RFI” or “jamming”2) can lead to a performance degradation of the computed aircraft position.

To ensure the robustness of the Airbus aircraft architecture, the systems also take into account inertial references and/or NAVAIDs (i.e. VOR, DME) to augment and complement the aircraft
position’s accuracy, integrity, availability and continuity.

1Global Navigation Satellite System (GNSS) refers to a worldwide position and time determination system that includes one or more satellite constellations, aircraft receivers and system integrity monitoring, augmented as
necessary to support required navigation performance for the intended operation. It includes the United States Global Positioning System (GPS) currently used by commercial aircraft, and augmentation systems such as
Satellite Based Augmentation System (SBAS).

2GNSS Radio Frequency Interferences (GNSS RFI): The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in GNSS frequency band (1559 – 1610 MHz). GNSS RFI
may induce a degradation of position performance (such as lower accuracy and integrity) or loss of information.
Therefore, when GNSS signals from satellite constellation are lost or degraded by interferences, depending on the duration, aircraft capabilities can be maintained, limited or lost during the
flight. These effects on aircraft capabilities shall be considered in flight crew decisions: for example, assessment of the capability to fly PBN routes, procedures and approaches.

The objective of this article is to clarify the impact of GNSS signal loss and GNSS RFI on aircraft operations, and to provide recommendations on how to handle these events in the daily
aircraft operations.

This document is divided into three parts:

1. Cockpit effects that can be observed by the flight crew during GNSS RFI.
2. Operational considerations to be considered during flight preparation/flight/post-flight phases.
3. Maintenance recommendations to be considered during post-flight analysis after GNSS RFI.

Note: The STC solutions or cabin impacts (such as BFE in-flight entertainment/connectivity) are not considered in this article.

1. COCKPIT EFFECTS

This chapter covers A300-600, A310 autonomous architecture (i.e. GPS outputs are directly connected to the FMS), and A320, A330, A340, A380 and A350 aircraft in hybrid configuration
(i.e. GPS outputs sent to the IRS which sends a “hybridized” position to the FMS).

These aircraft are fitted with two MMRs, three ADIRUs and two (A300-600/A310/A320/A330/A340/A380) or three (A350) FMS to compute the aircraft position. The A/C position is used by
the FMS for navigation purposes.

In case GPS data is lost due to GNSS RFI affecting both MMRs, the aircraft position source will switch to pure IRS and will enter into the so-called coasting mode. If the integrity of GPIRS
data falls below a certain threshold, then the position source will switch to other radio navigation based solutions (from FMS) according to the availability of DME and VOR. If NAVAIDs are
not available, the aircraft position solution will switch to IRS only.

Besides, MMRs elaborate deviations relative to a flight path and distance to a runway datum point in xLS modes such as FLS, GLS and SLS. In case GPS data is lost due to GNSS RFI affecting
both MMRs, the xLS modes GLS, SLS, FLS using GPS data will not be available.

- Cockpit effects are covered in section 1.1

- Description of the effects on systems and functions are covered in section 1.2
DESCRIPTION OF COCKPIT EFFECTS

Important note: The below described effects may be observed if an A/C is operating in an area where RFI are present. Depending on the interference features (and A/C functions), the GPS
receivers may be affected differently leading to the potential appearance of one or several of the effects described below.

1.1.1 A300-600 / A310

Function ND/CDU ECAM ALERT / lights Other Effects

With clock standard APE5100-1, when UTC selector is set on “GPS” and
the GPS 1 does not provide UTC time anymore to the clock, the clock
Clock
provides an internal time. The precision of the internal time diverges from
UTC time. The FMS predictions may also diverge.
NAV/ADC GPS 1(2)(1+2) FAULT
GPS(*) GPS PRIMARY LOST
GPS 1(2)(1+2)
TAWS (*) TERR TERR MODE FAULT light Spurious terrain alerts (1).
Time
Inconsistent time and FMS predictions (time drift or jumps (1)).
Predictions
Table 1.1: A300-600/A310 Cockpit Effects description

(*) Optional function, the effects can be shown only if the option has been selected for a given A/C
(1)Spurious terrain alerts and inconsistent time jump are not systematically observed in GNSS RFI areas. Such events do not occur in case of GPS total loss. Please report
inconsistent information observed in GNSS RFI areas to Airbus to allow a safety analysis and follow-up of the event. Refer to section 3.3 for a list data needed to investigate the
event.

1.1.2 A320 / A330 / A340

Function ND/PFD ECAM ALERT ECAM STATUS Other Effects

(a) NAV ADS-B TRAF FAULT (a) ADS-B TRAF

ADS-B IN (b) NAV ADS-B FAULT (b) ADS-B
(*)
ND: ADS-B inhibited if NAV GPS 1
(also called
FAULT + NAV GPS 2 FAULT
ATSAW)
(a) Post / (b) Pre FWC std: A320 H2-F7; A330 T5; A340 L13
NAV ADS-B RPTG 1(2)
ADS-B OUT
FAULT ISI1
std DO- ADS-B RPTG
inhibited if NAV GPS 1
260B (*)
FAULT + NAV GPS 2 FAULT
Aircraft NAV FM/GPS POS
Position DISAGREE
CPDLC and ADS-C shall be
considered as lost if the aircraft
time reference is more than +/-
1 s from UTC reference (Refer
to clock item or FCOM
description on the operation of
clock Internal Mode).
ATC Note: the position information
DATALINK inserted in ADS-C reports will
have a downgraded accuracy.
The downgrading will be
detectable by ground controllers
via one specific field of ADS-C
reports called Figure of Merit set
to one specific value (30Nm) in
order to inform of the GPS loss.
Computed time to cool the
engine will be augmented by 3
Bow Rotor minutes (only applicable to
A320 Neo family with PW1100
engines)
With clock standard APE5100-1
(A320/A330/A340), APE5100
(A330/A340), when UTC
selector is set on “GPS” and the
GPS 1 does not provide UTC
Clock time anymore to the clock, the
clock provides an internal time.
The precision of the internal
time diverges from UTC time,
affecting ATC Datalink and FMS
predictions. TFU1
Backup altitude, backup
mach, backup
characteristic speed may
DBUS NAV BKUP SPD FAULT BKUP SPD FAULT
not be available.
(only applicable to UAMM
Step 2 function on
 A320/A330/A340 aircraft)
MOI

If FLS selected:
LOC & G/S deviations, and
distance to the runway FLS LIMITED TO F-APP +
FLS (*)
may not me available RAW if GPS PRIMARY LOST
without any fault on ECAM
TFU3

If GLS selected:
- GLS Red flag
- With NDs in the ROSE
mode:
o LOC & G/S Red flags GLS 1(2)(1+2)
o LOC & G/S deviation
bar out of view GPWS INOP SYS if GLS 1
Same behaviour on PFD NAV GLS 1(2)(1+2) fault occurs
GLS (*)
FAULT GLS AUTOLAND inhibited if
GLS LOC & G/S deviations, NAV GLS 1 FAULT + NAV GLS
and distance to the 2 FAULT
runway may not be
available, without any
fault on ECAM TFU3
NAV GPS 1(2)(1+2)
GPS GPS PRIMARY LOST GPS 1(2)(1+2)
FAULT

OANS (*) ARPT NAV POS LOST

SURV ROW/ROP LOST

ROW/ROP
inhibited if NAV GPWS TERR ROW/ROP
(*)
DET FAULT
Degraded voice/datalink
SATCOM communications (3).

If SLS selected:
- SLS Red flag
- With NDs in the ROSE
mode:
o LOC & G/S Red flags
o LOC & G/S deviation
bar out of view NAV SLS 1(2)(1+2)
Same behaviour in PFD FAULT SLS 1(2)(1+2)
SLS (*)
SLS limited to APPR1
SLS LOC & G/S deviations,
and distance to the
runway may not be
available, without any
fault on ECAM TFU3
 NAV GPWS TERR DET
GPWS TERR
TAWS (*) FAULT Spurious terrain alerts (2).

GPWS (4)
NAV GPWS FAULT (4)

Inconsistent time and FMS

Time
predictions (time drift or time
Predictions jumps (2)).
Wind Inconsistent wind speed
Information and direction. (1) (2)
Table 1.2: A320/A330/A340 Cockpit Effects description

(*) Optional function, the effects can be shown only if the option has been selected for a given A/C
Only applicable with Honeywell ADIRU Block III, as the computation of the wind speed and direction uses the hybrid GPS/IRS ground speeds (ADIRU standards before Block III
(1)

use only IRS).

(2)Spurious terrain alerts, inconsistent time jump, and inconsistent wind information are not systematically observed in GNSS RFI areas. Such events do not occur in case of GPS
total loss. Please report inconsistent information to Airbus to allow a safety analysis and follow-up of the event. Refer to section 3.3 for a list data needed to investigate the event.
(3) Impacts are due to the SATCOM frequency band (1626.5 MHz) close to the GPS L1 frequency band (1575.42 MHz).
(4) Due to the Radio Altimeter rejection by TAWS computer during the ‘RA reasonableness check’ (which uses GPS geometric altitude).

Other effects:
 GPS Data dashed on GPS MONITOR pages of MCDUs
 Total GPS loss leads to a red flag (“ALT”) on grey background and red scale displayed on PFD, in case no air data are available.

1.1.3 A380

Function ND / PFD ECAM ALERT ECAM STATUS Other Effects

ADS-B POS RPTG LOST

ADS-B OUT
ADS-B RPTG 1(2)(1+2)
Aircraft
NAV FM/GPS POS DISAGREE
Position
CPDLC and ADS-C shall be
considered as lost if the aircraft
time reference is more than +/-1 s
ATC from UTC reference (Refer to clock
DATALINK item or FCOM description on the
operation of clock Internal Mode).
Note: the position information
inserted in ADS-C reports will have
 a downgraded accuracy. The
downgrading will be detectable by
ground controllers via one specific
field of ADS-C reports called Figure
of Merit set to one specific value
(30Nm) in order to inform of the
GPS loss.
With clock standard APE5100-3,
when UTC selector is set on “GPS”
and the GPS 1 does not provide
UTC time anymore to the clock, the
Clock clock provides an internal time. The
precision of the internal time
diverges from UTC time, affecting
ATC Datalink and FMS predictions.
TFU1

If FLS selected:
FLS LOC & G/S deviations, and NAV FLS 1(2)(1+2) CAPABILITY LOST
FLS LIMITED TO F-APP+RAW if GPS
FLS (*) distance to the runway may Detected loss of deviations from FWC
PRIMARY LOST
not be available, without any 70B (Batch 7) TFU3
fault on ECAM TFU3
If GLS selected:
- GLS Red flag on ND
- With NDs in the ROSE mode: NAV GLS 1(2)(1+2) FAULT
o LOC & G/S Red flags SURV GPWS 1+2 FAULT (only shown
o LOC & G/S deviation bar out GLS 1(2)(1+2)
on ground for maintenance purposes,
of view GLS AUTOLAND
only when both GLS are lost)
GLS (*) Same behaviour on PFD inhibited in case of NAV GLS 1 FAULT
+ NAV GLS 2 FAULT
NAV GLS 1(2)(1+2) CAPABILITY
GLS LOC & G/S deviations, GPWS 1+2
LOST Detected loss of deviations from
and distance to the runway
FWC 70B (Batch 7) TFU3
may not be available, without
any fault on ECAM TFU3
GPS GPS PRIMARY LOST NAV GPS 1(2)(1+2) FAULT GPS 1(2)(1+2)

OANS (*) ARPT NAV POS LOST

PFD: RUNWAY TOO SHORT

SURV ROW/ROP LOST
ROW/ROP could be spuriously raised on ROW/ROP
inhibited in case of NAV GPS 1 FAULT +
(*) OANS Std pre 6.3 (refer to BTV (*)
NAV GPS 2 FAULT
TFU 34.38.00.002)
SATCOM SATCOM Degraded voice/datalink
communications (3).
 If SLS selected:
- SLS Red flag
- With NDs in the ROSE mode:
o LOC & G/S Red flags
o LOC & G/S deviation bar out
of view NAV SLS 1(2)(1+2) FAULT
SLS 1(2)(1+2)
SLS (*) Same behaviour in PFD SLS limited to APPR1

SLS LOC & G/S deviations, and

distance to the runway may
not be available, without any
fault on ECAM TFU3
SURV TERR SYS 1(2)(1+2) FAULT TERR SYS 1(2)(1+2) Spurious terrain alerts (2).
TAWS
SURV GPWS 1(2)(1+2) FAULT (4) GPWS 1(2)(1+2) (4)

TCAS SURV TCAS 1+2 FAULT (4) TCAS 1+2 (4)

Inconsistent time and FMS

Time
predictions (time drift or time
Predictions
jumps (2)).
Wind Inconsistent wind speed
Information and direction (1) (2).
WX GND CLUT(anti clutter
WXR SURV PRED W/S 1+2 FAULT (4) PRED W/S 1+2 (4)
function not available)
Table 1.3: A380 Cockpit Effects description

(*) Optional function, the effects can be shown only if the option has been selected for a given A/C
Only applicable with Honeywell ADIRU Block III, as the computation of the wind speed and direction uses the hybrid GPS/IRS ground speeds (ADIRU standards before Block III
(1)

use only IRS).

(2)The spurious terrain alert, inconsistent time jump, and inconsistent wind information are not systematically observed in GNSS RFI area. Such events do not occur in case of GPS
total loss. Please report inconsistent information to Airbus to allow a safety analysis and follow-up of the event. Refer to section 3.3 for a list data needed to investigate the event.
(3) Impacts are due to the SATCOM frequency band (1626.5 MHz) close to the GPS L1 frequency band (1575.42 MHz).
(4) Due to the Radio Altimeter rejection by AESS computer during the ‘RA reasonableness check’, which uses GPS geometric altitude.

Other effects:
 Data dashed on POSITION/GPS Page of both MFD
 Total GPS loss leads to a red flag (“ALT”) on grey background and red scale displayed on PFD, in case no air data are available.

1.1.4 A350
Function ND/PFD ECAM ALERT ECAM STATUS Other Effects

ADS-B IN (*)
(also called
ATSAW or SURV ADS-B TRAFFIC 1(2)(1+2) FAULT ADS-B TRAFFIC 1(2)(1+2)
ADS-B
Traffic)
ADS-B POS RPTG LOST
ADS-B OUT
ADS-B RPTG 1(2)(1+2)
NAV GNSS/ACFT POS DISAGREE
Aircraft
NAV GNSS 1+2 REJECTED BY IRs
Position
NAV GNSS 1(2) REJECTED BY IRs TFU2

ANF (*) ARPT NAV POS LOST

CPDLC and ADS-C shall be

considered as lost if the
aircraft time reference is
more than +/-1 s from UTC
reference.
Note: the position information
inserted in ADS-C reports will
ATC have a downgraded accuracy.
DATALINK The downgrading will be
detectable by ground
controllers via one specific
field of ADS-C reports called
Figure of Merit set to one
specific value (30Nm) in
order to inform of the GPS
loss.
If FLS selected:
FLS LOC & G/S deviations, and distance FLS LIMITED TO F-APP+RAW if
FLS (*)
to the runway may not be available, GNSS 1+2 FAULT
without any fault on ECAM
If GLS selected: GLS 1(2)(1+2)
- GLS Red flag NAV GLS 1(2)(1+2) FAULT
GLS AUTOLAND
GLS (*) - With NDs in the ROSE mode: GLS limited to APPR1 if only one side lost
o LOC & G/S Red flags inhibited in case of NAV GLS 1
o LOC & G/S deviation bar out of view FAULT + NAV GLS 2 FAULT
 Same behaviour in PFD
Note: GLS LOC & G/S deviations, and
distance to the runway may not be
available, without fault on ECAM
GPS NAV PRIMARY LOST NAV GNSS 1(2)(1+2) FAULT GNSS 1(2)(1+2)
NAV RNP AR CAPABILITY
DOWNGRADED
if NAV GNSS x FAULT x=1 or 2
RNP AR ECAM status/INFO:
only “FOR RNP AR : MINIMUM LIMITED
displayed TO RNP 0.3” RNP AR (in case of RNP AR
RNP AR CAPABILITY LOST
during RNP Note: post FWS S5.2 and post PRIM P8 CAPABILITY LOST)
AR occurrence rate is reduced (ref TFU
operations 22.00.00.201)

NAV RNP AR CAPABILITY LOST

If NAV GNSS 1+2 FAULT

ROW/ROP SURV ROW/ROP LOST ROW/ROP

(*) inhibited in case of NAV GNSS 1+2 FAULT BTV

SATCOM SATCOM Degraded

voice/datalink
communications (2).
If SLS selected:
- SLS Red flag
- With NDs in the ROSE mode:
o LOC & G/S Red flags NAV SLS 1(2)(1+2) FAULT
o LOC & G/S deviation bar out of view SLS 1(2)(1+2)
SLS (*) SLS limited to APPR1
Same behaviour in PFD
Note: SLS LOC & G/S deviations, and
distance to the runway may not be
available, without any fault on ECAM
SURV TERR SYS FAULT TERR SYS
TAWS Spurious terrain alerts (1).
SURV GPWS FAULT (3) GPWS (3)
TCAS SURV TCAS 1+2 FAULT (3) TCAS 1+2 (3)

Inconsistent time and FMS

Time
predictions (time jumps
Predictions (1)).ISI2

MAP NOT AVAIL

WXR WX GND CLUT (anticlutter function not SURV PRED W/S 1+2 FAULT (3) PRED W/S 1+2 (3)

available)
 Table 1.4: A350 Cockpit Effects description

(*) Optional function, the effects can be shown only if the option has been selected for a given A/C
(1)Spurious terrain alerts and inconsistent time are not systematically observed in GNSS RFI areas. These events do not occur in case of GPS total loss. Please report inconsistent
information to Airbus to allow a safety analysis and follow-up of the event. Refer to section 3.3 for a list data needed to investigate the event.
(2) Impacts are due to the SATCOM frequency band (1626.5 MHz) close to the GPS L1 frequency band (1575.42 MHz).
(3) Due to the Radio Altimeter rejection by AESS computer during the ‘RA reasonableness check’ (which uses GPS geometric altitude).

Other effects:
 Data dashed on POSITION/GNSS Page of both MFD
 Total GPS loss leads to a red flag (“ALT”) on grey background and red scale displayed on PFD, in case no air data are available.
Summary of functional and system effects

The tables below contain the functional and system effects corresponding to cockpit effects described in section 1.1.
Note: These alerts/warnings could arise in case of GNSS RFI, however all of the described functional or system effects may not be observed on every flight impacted by GNSS RFI.

1.1.5 Navigation
 A320
SYSTEMS A300-600/A310 A380 A350
A330/A340

All Phases: Loss of GPS and SBAS-based Navigation functions for the duration of the loss.
All Phases: Loss of GPS-
MMR
based Navigation functions. Approach & Landing: Loss of FLS, GLS and
Approach & Landing: Loss of FLS, GLS and SLS deviations.
SLS deviations and SLS deviations.

All Phases: The hybridization between GPS

measurements and IRS data is lost and
GPIRS position enters into coasting mode.
GPIRS position drifts when not updated via
All Phases: The hybridization between GPS measurements and GPS measurements.
No effect. IRS data is lost and GPIRS position enters into coasting mode. In flight: the A/C position switches to an
GPIRS position drifts when not updated via GPS measurements. alternate navigation mode that offers the
ADIRU IRU initialization performed best position solution accuracy and integrity
with the last memorized among: radio NAVAIDs and IRS position.
position. During alignment, flight crew needs to enter position manually to
On ground: the A/C position switches on IRS
align IRS.
position.
Time data are maintained according to
ADIRS internal clock
During alignment, flight crew needs to enter
position manually to align IRS.
All Phases: Clock will not be synchronized with UTC time provided by GPS; Clock is maintained
All Phases: Clock will not be synchronized
based on its internal reference. At aircraft power up the UTC displays zero’s in case of
Clock with UTC time provided by GPS; Clock is
unavailability of GPS signal. For initialization of the clock the Pilot has to manually input the
maintained based on ADIRS clock function.
time, using SET, INT; if GPS is resumed then change the knob to GPS.
Approach & Landing: GLS Approach & Landing: GLS and SLS
parameters (deviations, course, parameters (deviations, course, and
Approach & Landing: GLS
ISIS N/A and channel) are not available. channel) are not available during approach
deviations are not available.
Aircraft position and velocity and landing. Aircraft position and velocity
coming from MMR is invalid. coming from MMR is invalid.
Approach functions requiring Approach functions requiring GPS
GPS are not available: GLS, are not available: GLS, FLS (in Approach functions requiring GPS are not
FLS (in case of RNAV (GNSS)) case of RNAV (GNSS)) and RNP available: SLS, GLS, FLS (in case of RNAV
Flight Guidance
and RNP AR. AR. (GNSS)) and RNP AR.
FMGC (A320) Approach function receives
Non availability of Pre- Non availability of Pre-Capture Non availability of Pre-Capture Zone of the
FMGEC (A330/A340) only ILS data
Capture Zone of the LOC Zone of the LOC Beam in case of LOC Beam in case of NAV PRIMARY loss.
FCGU/PRIM (A380&A350)
Beam in case of GPS GPS PRIMARY loss. The functions BTV, ROW/ROPS are not
PRIMARY loss. The functions BTV, ROW/ROPS available
are not available.
 Flight Management The aircraft position solution All Phases: The aircraft position provided by
All Phases: The aircraft position solution will switch from GPIRS to
FMGC (A320) will switch to radio NAVAIDs the ADIRU is used irrespective of GPS loss.
radio NAVAIDs and inertial position.
FMGEC (A330/A340) or inertial position. GPS data are dashed in the GNSS monitor
GPS data are dashed in the GPS monitor page.
FMS (A380&A350) page.
Approach & Landing: The aircraft position
Airport Navigation Approach & Landing: The aircraft position cannot be computed
used by ANF is provided by ADIRU.
OANS and displayed on the airport moving map.
N/A Loss of support to Airport Navigation,
(A320/A330/A340/A380) Loss of support to Airport Navigation, Runway Approaching
Runway Approaching Advisory, BTV/ROPS
ANF (A350) Advisory and BTV/ROPS (on A380 only) functions from OANS.
and TOS2 functions from ANF.
Table 1.5: Functional and System Effect for Navigation System

Surveillance

The table below contains the functional and system effects corresponding to cockpit effects on the ND, ECAM alerts/status/ INOP sys.

A320
SYSTEMS A300-600/A310 A380 A350
A330/A340
All Phases: Loss of ATSAW Part of AESS Part of AESS
TCAS No effect
function(*) ATSAW function not available on A380 All Phases: Loss of ATSAW function
Part of AESS
All Phases: GPS parameters are invalid within ADS-B OUT messages (position integrity
All Phases: GPS parameters are invalid within ADS-B OUT tagged as degraded).
XPDR
messages (position integrity tagged as degraded). Note: A380 and A350 ADS-B function is more robust with respect to A320/A330/A340 as
it is based on GPIRS position. GPIRS position enters in coasting mode and can remain
available longer than GPS position.
Take-off, en-route & approach:
In case of invalid GPS position,
the TAWS uses the alternate
position computed by the FMS or Part of AESS.
No effect
the IRS. All Phases: No immediate loss thanks to back-up positioning (FMS, IRS) but some
TAWS In case of invalid GPS data,
degradations may be expected after certain time :
(EGPWS / GPWS) the TAD and TCF functions
Approach , Landing & on Ground
(T3CAS will switch to data from
: Loss of ROW/ROP ,RAAS – Potential loss of envelope modulation (when position too degraded)
A320/A330/A340) FMS.
functions(**) – Potential loss of predictive terrain alerts and display on ND (when position too
degraded)
Loss of terrain function when
GPS FOMs exceed the current
RNP according to flight phases
Part of AESS
WXR No effect No effect All Phases: WXR – Potential loss of ground declutter function (when position too
degraded)
 Table 1.6: Functional and System Effect Description for Surveillance Systems

(*) only if ATSAW function configured

(**) only if GPS configuration and RAAS function activated

1.1.6 Communication

A320
SYSTEMS A300-600/A310 A380 A350
A330/A340

SATCOM SATCOM communication may be degraded

AFN messages timestamp will not be synchronized with UTC time provided by GPS. The source of the timestamp switches
to either: ADIRU (A350 only), CLOCK, CMC/CFDIU.
ATSU (A320/A330/A340) N/A
However, position information inserted in ADS-C reports will have a downgraded accuracy. The downgrading will be
ATC (A350/A380)
detectable by ground controllers via one specific field of ADS-C reports called Figure of Merit set to one specific value
(30Nm) in order to inform of the GPS loss.
Table 1.7: Functional and System Effect Description for Communication Systems

RELATED WISE ARTICLES

The following articles (referenced across this document) provide additional details on some specific aircraft configurations affected by GNSS interferences:

Technical Follow Up

1. 31.21.00014 “Electrical Clock - Time drift linked to GNSS Radio Frequency Interferences”: for A300/A310/A320/A330/A380 aircraft equipped with clock APE5100-1 or APE5100-3.
2. 34.10.00066 “NAV GNSS 1(2) Rejected b IRS”: for A350 aircraft.
3. 34.36.00.030 “MMR GLU-925: GPS locked after Radio Frequency Interferences (RFI) exposure”: for aircraft equipped with COLLINS Aerospace MMR GLU-925.
4. 34.38.00.002 “Spurious RWY TOO SHORT message due to inaccurate OANC A/C position computation”: for A380 aircraft equipped with OANS standard A5.2 and A6.2.

In Service Information
1. 34.52.00035 “NAV ADS-B RPTG x FAULT in GPS degraded environment”: for A320 and A330 aircraft
2. 46.00.00057 “FSA-NG Time acquisition”: for A350 aircraft.

Modification Operational Impact

1. 22.00.00101 “AUTO FLIGHT - GENERAL - CERTIFY AND DEFINE UAMM (Unreliable Airspeed Mitigation Means) STEP 2 FUNCTION”: For A320
2. 27.00.00109 “FLIGHT CONTROLS- GENERAL - ACTIVATE UAMM STEP2 FONCTION BY WIRING DSI ON FCPC”: For A330
2. OPERATIONAL CONSIDERATIONS

FCOM PROCEDURES AND REPORTING

The effects of GNSS RFI detailed in section 1 should be considered in airline’s operations in order to ensure the safe operation of the aircraft.
 Refer to the Airbus recommended procedures of the FCOM manual in section:
o A350: NORMAL PROCEDURES - SUPPLEMENTARY PROCEDURES - GNSS INTERFERENCES
o Other programs: NORMAL PROCEDURES - SUPPLEMENTARY PROCEDURES - GPS INTERFERENCES

In addition, Airbus recommends to perform the following actions after a flight with possible GNSS RFI:
- Flight crew should report possible GNSS RFI and associated cockpit effects to the maintenance team,
- Maintenance team should apply recommended action detailed in section 3 (system tests, data collection, reporting to Airbus engineering or flight operations support),
- Operator should report any identified suspected GNSS RFI events to regional (e.g. ANSPs) and international organizations (e.g. EUROCONTROL’s Voluntary ATM Incident Reporting (EVAIR), refer to
https://www.eurocontrol.int/service/eurocontrol-voluntary-atm-incident-reporting) in order to facilitate and accelerate GNSS RFI event confirmation/resolution, and generate NOTAM to operators’
community.

UNDUE TAWS ALERTS

Airbus has received several event reports from Operators of unexpected TAWS alerts in flight interpreted as undue and potentially linked to GNSS interferences.

The TAWS equipment installed on Airbus fleet have been certified in accordance with the applicable technical/qualification specifications and airworthiness requirements. As an input for the
vertical and horizontal position, the GPS data or Radio Altimeters are used. Nowadays, some context of operations (e.g., military areas) can interfere with the external GPS or Radio Altimeter
signal. These phenomena can generate some undue TAWS alerts.

Airbus, as an aircraft manufacturer, provides in the FCOM a directive procedure in the section PRO-ABN-SURV-[MEM] EGPWS/TAWS WARNINGS that defines how the flight crew has to react
to a real terrain threat. Airbus does not intend to introduce any delay by the introduction of conditions in the application of the TAWS warning procedure.

However, the Operators may perform a safety assessment based on their knowledge of the context of the operations (e.g. knowledge of the departure, cruise, approach operations, aircraft lateral and vertical
position, consideration of cold weather operations, clear knowledge of the environmental conditions and terrain or interference threats, etc…). This assessment may allow Operators to define guidelines
and brief the pilots on how to address expected Undue TAWS alerts linked to GNSS Interference, such as:

 Potentially disregard an anticipated undue TAWS alert: prepare the crew to potential undue alerts at specific locations to avoid delay in procedure application for
genuine ones by making decisions during flight.

 Inhibit temporary GPWS predictive modes (TERR PB-SW OFF) over areas where predictive Undue TAWS alerts are expected to be recurrent.
Important notes :
 Inhibition of GPWS predictive modes implies a deactivation of a Safety Net. Thus, it requires an associated procedure ensuring the reactivation after leaving
the affected area in a timely manner.
 GPWS predictive modes inhibition in approach can lead to an increased risk of Mode 2 nuisance TAWS alerts at certain locations (e.g., cliff on the approach
path). Further information is given below in “design specificities”.
 The decision to inhibit the predictive GPWS predictive modes must not be based on flight crew judgment only but briefed before the flight.

As the interference threat evolves with time, we recommend updating the threat analysis on a regular basis.

The following design specificities should be taken into consideration for safety assessment and guidelines definition:
  The GPS deselection via MCDU or MFD has not impact on TAWS:
o GPS deselection only inhibits the use of GPS inputs for the navigation data computation. It leads to GPS PRIMARY LOST (NAV PRIMARY LOST on A350). The TAWS system will still
use GPS based data, if available, regardless of the GPS deselection.

 GPWS predictive modes, based on a terrain database, use GNSS inputs as primary position source. An inconsistent GNSS position input can lead to an Undue predictive
TAWS alert. GPWS basic modes do not use GNSS based inputs.

 Impact of GPWS predictive modes inhibition (TERR P/B to OFF):

o A/C equipped with TAWS computers ACSS T2CAS & T3CAS (all P/N) and Honeywell EGPWS MARK V-A P/N 69000942-152/-252:
 These TAWS computers implement an algorithm, based on airport and terrain databases, inhibiting nuisance Mode 2 alerts when predictive modes are active.
 The deactivation of predictive modes on A/C equipped with these TAWS equipment, leads to reactivation of basic TAWS Mode 2 increasing the risk of nuisance at certain
locations (e.g., cliff on the approach path leads to sudden radio altitude decrease and high terrain closure rate):

These alerts are as per design but not appropriate in the particular context of the A/C flying the published approach path.

3. Maintenance RECOMMENDATIONS

The alerts described in section 1 may point to a real defect of a system. In order to confirm that the events were not due to equipment failure, maintenance actions need to be carried out.

The required maintenance actions depend on the context under which the faults have been observed. In this article, we consider three different use cases:

1. Case 1: Transient symptoms observed when A/C overflies a known GNSS RFI area
2. Case 2: Transient symptoms observed in an area not known for GNSS RFI
3. Case 3: Symptoms observed during GPS interferences exposure not covered in section 1

CASE 1 – TRANSIENT SYMPTOMS OBSERVED WHEN A/C OVERFLIES A KNOWN GNSS RFI AREA

In this case, symptoms described in section 1 of this article are confirmed to be transient and observed when the A/C was overflying a known GPS interference area (e.g. NOTAM available
or analysis/experience confirmed GNSS disturbances affecting this area). Effects disappear during flight after leaving the affected area.

Once on ground, AIRBUS recommends performing the following actions:

Note: The list of associated maintenance tasks references can be found in Table 3.1
1. Reset both MMR 1 and MMR 2 (power off >10 sec)
2. If GPS function is affected:
o Perform MMR 1 and MMR 2 BITE test
o Perform IR system test (Step not applicable to A300-600/A310)
3. If GLS, SLS or FLS functions are affected, perform MMR 1 and MMR 2 BITE test (if not performed in previous step)
4. If ADS-B Out function was affected, perform ATC1 and ATC2 BITE test
5. If OANS function was affected, perform OANS BITE test (Step not applicable to A300-600/A310)
6. If TAWS function was affected, perform TAWS BITE test
7. If ADS-B In (ATSAW) function was affected, perform TCAS BITE test (Step not applicable to A300-600/A310)
8. If ROW/ROP function was affected, perform (Step not applicable to A300-600/A310)
o A320/A330/A340/A350 family: GPWS BITE test
o A380: OANS system test

If all the tests are OK neither further troubleshooting nor LRU removal is required. Please, note that new LRUs will exhibit same behavior when exposed to the same interferences.

If a fault is confirmed, perform troubleshooting as per the applicable TSM task.

Note: With Collins MMR GLU-920, GLU-925 the following faults will be recorded on the PFR if the MMR is not able to track satellites during more than 15 minutes.
- GPS ANTENNA1(43RT1) /COAX CABLE/MMR1(40RT1)) and/or
- GPS ANTENNA2(43RT2) /COAX CABLE/MMR2(40RT2))
In this case, the fault is associated to TSD: “GLS-P NO SATELLITES TRKD” or “GLS-M NO SATELLITES TRKD”.
If triggered over known RFI area, no GPS antenna issue is to be suspected.

With newer MMR standards, Collins GLU-2100 and Honeywell IMMR, no GPS antenna fault is raised with no satellite tracked. After 15 minutes of satellite loss, the following faults are
logged:
- MMR1(40RT1) /SIGNAL IN SPACE FEEDBACK and/or
- MMR2(40RT2) /SIGNAL IN SPACE FEEDBACK

Special cases:
- If the GPS interference is still present on ground, the tests might not pass. In case of known interference on ground, the operator can either move the A/C to a non-affected location or apply MEL for
affected equipment. System’s nominal behavior should be retrieved soon after leaving the interference area.
- Please report the event to AIRBUS if normal system behavior was not recovered after exiting the RFI area.

TASK A/C TYPE AMM / MP(A350) REFERENCE

A320/A330/ AMM Task 34-36-00-860-801-A – Reset of the Multi-Mode Receiver

MMR A340/A380
reset MP TASK A350-A-34-36-XX-00001-398A-A Reset of the Multi-Mode
A350
Receiver (MMR)
 TASK A/C TYPE AMM / MP(A350) REFERENCE

AMM TASK 34-14-00-740-004-A SYSTEM TEST of the Inertial Reference

A320FAM
(IR)
IR AMM TASK 34-14-00-740-803-A SYSTEM TEST of the Inertial Reference
A330/A340
System (IR)
test A380 AMM TASK 34-10-00-740-802-A BITE Test of the IR (System Test)
AMM TASK A350-A-34-1X-XX-00001-343A-A BITE Test of the Inertial
A350
Reference (IR) (System Test)
A320/A330/ AMM Task 34-36-00-740-003-A – BITE test of the MMR
A340
MMR A380 AMM Task BITE Test of the MMR (System Test
BITE test MP TASK A350-A-34-36-XX-00001-343A-A – BITE Test of the Multi-Mode
A350
Receiver (MMR) (System Test)
A300-600/A310 AMM 34-36-00 P. Block 501 MMR BITE test
ATC standalone: AMM Task 34-52-00-74-004-A – BITE Test of the ATC
T3CAS: AMM Task 34-72-00-740-001-A – BITE Test of the T/TISS 
A320
SUBTASK 34-72-00-740-053-A C. BITE Test of the T/TISS (ATC2
part)
A330/A340 AMM Task 34-52-00-740-801-A – BITE test of the Air Traffic Control (ATC)
ATC
AMM Task 34-71-00-740-803-A – BITE Test of the AESS (Master AESU
BITE test A380
XPDR/TCAS Test)
MP Task A350-A-34-71-XX-02001-343A-A – BITE Test of the Aircraft
A350 Environment Surveillance System (AESS) (Master-AESU XPDR/TCAS
Module-Test)
A300-600/A310 AMM 34-52-00 P. Block 501 ATC Operational Test
OANS A320/A330/ AMM Task 34-38-00-740-801-A – BITE Test of the Onboard Aircraft
BITE Test A340/A380 Navigation System (OANS) (System Test)
GPWS: AMM Task 34-48-00-740-002-A BITE Test of the GPWS
EGPWS: AMM Task 34-48-00-740-002-B BITE Test of the GPWS
T2CAS: AMM TASK 34-43-00-740-004-A Bite Test of the T2CAS 
SUBTASK 34-43-00-740-054-A B.BITE Test of the T2CAS (TAWS
A320
GWPS part)
BITE Test T3CAS: AMM Task 34-72-00-740-001-A – BITE Test of the T/TISS 
SUBTASK 34-72-00-740-052-F B.BITE Test of the T/TISS (TAWS
part)
EGPWS: AMM TASK 34-48-00-740-801-B Operational Test of the
A330/A340
Enhanced Ground Proximity Warning (GPW) Computer by BITE
 TASK A/C TYPE AMM / MP(A350) REFERENCE

T2CAS: AMM Task 34-43-00-740-802-A BITE Test of the Traffic and Terrain
Collision Avoidance System (T2CAS)  SUBTASK 34-43-00-740-
054-A B.BITE Test of the T2CAS (TAWS part)
T3CAS: AMM TASK 34-72-00-740-801-A BITE Test of the T/TISS 
SUBTASK 34-72-00-740-051-D B.BITE Test of the T/TISS (TAWS
part)
AMM TASK 34-71-00-740-802-A – BITE Test of the AESS (Master AESU
A380
TAWS Test)
MP TASK A350-A-34-71-XX-01001-343A-A BITE Test of the Aircraft
A350
Environment Surveillance System (AESS) (Master AESU TAWS Module Test
A300-600/A310 AMM: 34-48-00, P. Block 501 GPWS operational test
TCAS: TASK 34-43-00-740-001-A BITE Test of the TCAS
T2CAS: AMM TASK 34-43-00-740-004-A Bite Test of the T2CAS 
SUBTASK 34-43-00-740-053-A A.BITE Test of the T2CAS (TCAS
A320 part)
T3CAS: AMM Task 34-72-00-740-001-A – BITE Test of the T/TISS 
SUBTASK 34-72-00-740-051-A A.BITE Test of the T/TISS (TCAS
part)
TCAS: TASK 34-43-00-740-801-A – BITE test of the Traffic Collision
Avoidance System (TCAS)
TCAS T2CAS: AMM Task 34-43-00-740-802-A BITE Test of the Traffic and
BITE Test Terrain Collision Avoidance System (T2CAS)  SUBTASK 34-43-
A330/A340
00-740-053-A A.BITE Test of the T2CAS (TCAS part)
T3CAS: AMM TASK 34-72-00-740-801-A BITE Test of the T/TISS 
SUBTASK 34-72-00-740-050-A A. BITE Test of the T/TISS (TCAS
part
AMM Task 34-71-00-740-803-A – BITE Test of the AESS (Master AESU
A380
XPDR/TCAS Test)
MP Task A350-A-34-71-XX-02001-343A-A – BITE Test of the Aircraft
A350 Environment Surveillance System (AESS) (Master-AESU XPDR/TCAS
Module-Test)

Table 3.1: Maintenance tasks references

CASE 2 – TRANSIENT SYMPTOMS OBSERVED IN AN AREA NOT KNOWN FOR GPS INTERFERENCE

In case a GNSS RFI is suspected and the area is not known to be affected (no NOTAM entry or previous experience), an analysis needs to be performed in order to confirm the root cause.
The analysis consists in the study of all potential sources of GNSS perturbation: aircraft and/or receiver failure, GNSS constellation anomaly, environment masking, multipath or space
weather. In case all of those potential sources are discarded, then it is likely that a GNSS RFI occurred.

Please report such a case to AIRBUS together with further information in order to allow an assessment of the event and to confirm if it can be linked to RFI or if regular troubleshooting is
required on A/C.

Information to be provided for analysis:

A300 / A310 A320 / A330 / A340 A380 A350

N/A Post Flight Report Post Flight Report Post Flight Report
CMS dump CMS dump
Flight data: Flight data: Flight data: Flight data:
- DFDR/QAR - DFDR/QAR - DFDR/QAR - DFDR/QAR
- DAR if customization available - SAR 58 (this report contains - SAR 99 (this report contains
including additional useful GPS information) useful GPS information)
GPS/ADIRU parameters
Pilot Report: Pilot Report: Pilot Report: Pilot Report:
- Detailed event report - Detailed event report - Detailed event report - Detailed event report
- Picture of FMS CDU pages: - Picture of FMS pages in - POSITION/GPS Page status - POSITION/GNSS Page status
- GPS MONITOR MCDU: during events ( MFD) during events ( MFD)
- POSITION MONITOR - GPS MONITOR
- - POSITION MONITOR
- IRS MONITOR
N/A MMR data: MMR data: MMR data:
- Troubleshooting Data (TSD) - Troubleshooting Data (TSD) - Troubleshooting Data (TSD)
- GPS REPORT for MMR - GPS REPORT - GPS REPORT
Rockwell Collins GLU-925, Accessible via OMT  Accessible via OMT 
GLU-2100 or Honeywell RMA SYSTEM REPORT TEST  SYSTEM REPORT TEST 
55B (*) ATA 34  MMR  ATA 34  MMR 
Accessible via MDCU  SPECIFIC DATA SPECIFIC DATA
SYSTEM REPORT TEST 
MMR  SPECIFIC DATA
N/A IR data: IR data: IR data:
- TSD of IR1, IR2 and IR3 - GPIRS IN-AIR REPORT - GPIRS IN-AIR REPORT
- GPIRS IN-AIR REPORT Accessible via OMT  Accessible via OMT 
(Northrop Grumman ADIRU SYSTEM REPORT TEST  SYSTEM REPORT TEST 
and Honeywell Block III(**) ATA 34  IR  SPECIFIC ATA 34  IR  SPECIFIC
Accessible via MDCU  DATA FUNCTIONS
SYSTEM REPORT TEST 
IR  SPECIFIC DATA
Table 3.2: Information to be provided to evaluate presence of GPS interferences

(*) MMR with “GPS REPORT” menu:

- Collins GLU-925 P/N 822-1821-430 (A320/A330/A340/A380)
- Collins GLU-925 P/N 822-1821-632 (A350)
- Collins GLU-2100 P/N 822-2532-300 (A320/A330/A350/A380)
- Honeywell RMA-55B P/N 066-50029-1161 (A320/A330/A340)
 (**) ADIRUs with “GPIRS REPORT” menu:
- Honeywell Block III P/N HG2030BE0x
- Northrop Grumman P/N 465020-0303-0318, 465020-0304-0318, P/N 465020-0303-0316, P/N 465020-0304-0316

Note for SAR files: SARxx file name contains the date and time of recorded data:
Example: SAR00585810181120043231 –> SAR 58; Date 20 Nov 2018; Time 04:32:31 UTC

If the event is confirmed to be related to GNSS RFI:

Recommendations given in chapter 3.1 apply.

Note: Reports of suspected GNSS outage or RFI should be transmitted to international organizations (e.g. EUROCONTROL's Voluntary ATM Incident Reporting (EVAIR), refer to
https://www.eurocontrol.int/service/eurocontrol-voluntary-atm-incident-reporting) or regional ANSPs in parallel of Airbus analysis, in order to produce an additional analysis of the GNSS
signals, accelerate GNSS RFI event confirmation/resolution, and generate NOTAM to operators’ community.

If the event is not confirmed to be related to GNSS interference

Regular troubleshooting to be applied as per TSM.

CASE 3 – EFFECTS DURING GPS INTERFERENCE EXPOSURE NOT COVERED IN CHAPTER 1 OR EVENTS REQUIRING FURTHER ANALYSIS

If an A/L suspects GNSS RFI and observes effects not covered in chapter 1 (or defined in chapter 1, but referring to this section 3.3), we recommend contacting AIRBUS for further event
analysis. For instance, AIRBUS has received reports about different kind of events potentially linked to GNSS RFI exposure such as map shift or ADS-B Out erroneous position.

These represent unexpected behaviour and require investigation.

We recommend A/Ls to provide AIRBUS with the following information along with the event report to help events analysis:

A300 / A310 A320 / A330 / A340 A380 A350

General GPS N/A Post Flight Report Post Flight Report Post Flight Report
analysis CMS dump CMS dump
information Flight data: Flight data: Flight data: Flight data:
(Equivalent - DFDR/QAR - DFDR/QAR - DFDR/QAR - DFDR/QAR
- DAR if customization - SAR 58 (this report - SAR 99 (this report
to Table 3.2)
available including contains useful GPS contains useful GPS
additional GPS/ADIRU information) information)
parameters
Pilot Report: Pilot Report: Pilot Report: Pilot Report:
- Detailed event report - Detailed event report - Detailed event report - Detailed event report
- Picture of FMS CDU - Picture of FMS pages in - POSITION/GPS Page - POSITION/GNSS Page
pages: MCDU: status during events ( status during events (
- GPS MONITOR - GPS MONITOR MFD) MFD)
 - POSITION MONITOR - POSITION MONITOR
- - IRS MONITOR

N/A MMR data: MMR data: MMR data:

- Troubleshooting Data - Troubleshooting Data - Troubleshooting Data
(TSD) (TSD) (TSD)
- GPS REPORT for MMR - GPS REPORT - GPS REPORT
Rockwell Collins GLU-925 Accessible via OMT  Accessible via OMT 
or Honeywell RMA 55B (*) SYSTEM REPORT SYSTEM REPORT
Accessible via MDCU  TEST  ATA 34  TEST  ATA 34 
SYSTEM REPORT MMR  SPECIFIC MMR  SPECIFIC
TEST  MMR  DATA DATA
SPECIFIC DATA
N/A IR data: IR data: IR data:
- TSD of IR1, IR2 and IR3 - GPIRS IN-AIR REPORT - GPIRS IN-AIR REPORT
- GPIRS IN-AIR REPORT Accessible via OMT  Accessible via OMT 
(Northrop Grumman SYSTEM REPORT SYSTEM REPORT
ADIRU and Honeywell TEST  ATA 34  IR TEST  ATA 34  IR
Block III(**)  SPECIFIC DATA  SPECIFIC
Accessible via MDCU  FUNCTIONS
SYSTEM REPORT
TEST  IR 
SPECIFIC DATA
In case of a T2CAS dump or EGPWS Depending on A/C GPWS Not possible to dump Not possible to dump
spurious dump computer configuration : AESU on wing. A/L can AESU on wing. A/L can
TAWS - T2CAS dump or contact Honeywell contact Honeywell
- T3CAS dump or
warning - EGPWS dump representatives. representatives.

In case of an - Air Traffic Control report together with ADS-B raw data containing position + integrity information (data to be requested
by A/L to authorities, not usually available at A/L level)
ADS-B Out - ATC transponder side in use during events
issue - Was the pilot requested to switch transponder? Did the situation change if done?
Other N/A FMS dump: FMS dump : FMS dump:
- A320: AMM TASK 22- - AMM TASK 22-70-00- - MP TASK A350-A-22-
70-00-610-006 860-804-A 7X-XX-01003-752A-A
- A330: AMM TASK 22-
70-00-610-008

Table 3.3: Information to be provided in case of different cockpit effect

4. GLOSSARY

A/C Aircraft
ACMS Aircraft Condition Monitoring System
ADIRS Air Data and Inertial Reference System
ADIRU Air Data and Inertial Reference Unit
AESS Aircraft Environment Surveillance System
AFN ATC Facilities Notification
ANF Airport Navigation Function
ATSAW Airborne Traffic Situation Awareness
ATSU Air Traffic Service Unit
BTV Brake To Vacate
BUSS Back Up Speed Scale
CFDIU Central Fault Display Interference Unit
CFDS Central Fault Display System
CMC Central Maintenance Computer
CMS Central Maintenance System
DAR Digital AIDS Recorder (A320)
DAR Digital ACMS Recorder (A330/A340/A380)
DBUS Digital Backup Speed
DFDR Digital Flight Data Recorder
DLCS Data Loading Configuration System
DMC Display Management Computer
DME Distance Measuring Equipment
ECAM Electronic Centralized Aircraft Monitoring
EFB Electronic Flight Bag
EGPWC Enhanced Ground Proximity Warning Computer
EGPWS Enhanced Ground Proximity Warning System
EICU EFB interface Control Unit
EIS Electronic Instrument System
EIU Electronic Instrument Unit
EPE Estimated Position Error
EPU Estimated Position Uncertainty
FANS Future Air Navigation System
FDIF Flight Data Interface Function
FLS FMS Landing System
FMC Flight Management Computer
FMG Flight Management Guidance and (Envelope)
(E)C Computer
FMS Flight Management System
FOM Figure Of Merit
FOMAX Flight Operation and MAintenance eXchanger
FWC Flight Warning Computer
FWS Flight Warning System
GBAS Ground Based Augmentation System
GLS GBAS Landing System
GNSS Global Navigation Satellite System
GPIRS GPS and IRS mixed data
GPS Global Positioning System
GPWC Ground Proximity Warning System
HDOP Horizontal Dilution Of Precision
HFOM Horizontal Figure Of Merit
HIL Horizontal Integrity Limit
HIPL Horizontal Integrity Protection Level
HUD Head Up Display
HUDC Head Up Display Computer
IFE In Flight Entertainment
IRS Inertial Reference System
ISIS Integrated Standby Instrument System
LOC Localizer
ELT Emergency Locator Transmitter
MCDU Multipurpose Control Display Unit
MFD Multi Functions Display
MMR Multi-Mode Receiver
ND Navigation Display
NSE Navigation System Error
OANS Onboard Airport Navigation System
PFD Primary Flight Display
PRAIM Predictive Receiver Autonomous Integrity
Monitoring
PRIM PRIMary System
PVT Position, Velocity, Time
RAAS Runway Awareness and Advisory System
RFI Radio Frequency Interference
RNP Required Navigation Performance
RNP AR Required Navigation Performance Authorization
Required
ROPS Runway Overrun Prevention System
ROW Runway Overrun Warning
RVSM Reduced Vertical Separation Minima
SATCOM SATellite COMmunication
SBAS Satellite Based Augmentation System
SCI Secure Communication Interface
SLS SBAS Landing System
TAWS Terrain Avoidance and Warning System
TCAS Traffic Alert and Collision Avoidance System
TOS Take Off Securing
UTC Universal Time Coordinated
VDOP Vertical Dilution Of Precision
VHF Very High Frequency
VIL Vertical Integrity Limit
VOR VHF Omnidirectional Range
WXR Weather Radar
XPDR Transponder
Survey for the Engineering Support section
 Annex

General Information
Potential impact: Maintenance, Operational Reliability
Key information:
Solution benefit:
First issue date: 22-FEB-2019 Issue date: 17-NOV-2023 Last check date: 17-NOV-2023

Technical parameters
ATA: 34-36
A/C type/serie: A300, A300-600, A310, A318, A319, A320, A321, A330, A340, A350, A380
Engine:
Engine manufacturer:
Fault code/ECAM
warning:
FIN:
Part Number:
Supplier:

Attachments
General:
- ISI_34.36.00049_Summary.docx

Links
Other articles (ISI/TFU):
- 31.21.00014, 34.10.00066, 34.36.00.030, 34.38.00.002, 34.52.00035, 46.00.00057
© Airbus SAS, 2023. All rights reserved. Confidential and proprietary document.The technical information provided in this article is for convenience and information purposes only. It
shall in no case replace the official Airbus technical or Flight Operations data which shall remain the sole basis for aircraft maintenance and operation. These recommendations and
information do not constitute a contractual commitment, warranty or guarantee whatsoever. They shall not supersede the Airbus technical nor operational documentation; should
any deviation appear between this article and the Airbus or airline's official manuals, the operator must ensure to cover it with the appropriate document such as TA, FCD, RDAS.
Access to WISE is supplied by Airbus under the express condition that Airbus hereby disclaims any and all liability for the use made by the user of the information contained in
WISE. It shall be used for the user's own purposes only and shall not be reproduced or disclosed to any third party without the prior consent of Airbus.