Aircraft-Related Occupancies
412. Aircraft-Related Occupancies
Because of the unique nature of occupancies related to aircraft manufacture,
repair, storage, and even flight control, provisions have been developed to
address the special conditions that may exist. Although the various uses fall into
different occupancy classifications, they all have one thing in common—they are
related to aircraft. Additional requirements related directly to aviation facilities
are found in Chapter 20 of the IFC.
412.3. Airport-traffic control towers.
These provisions are intended to reconcile the differences between the life-safety
needs of air-traffic control towers and the life-safety requirements in the body of
the code. The life and property loss in these towers has been very small even
though they have not complied completely with all of the code requirements in
the past. In developing these provisions, consideration was given to the inherent
qualities of the use, which makes the general requirements of the IBC
inappropriate. For example, air-traffic control personnel are required to undergo
medical examinations to ensure they are of sound body and mind. Recognition
was also given to the life-safety record of these uses and specific limitations,
which are imposed on the allowable size, type of construction, etc. The provisions
also require automatic fire-detection systems.
412.4. Aircraft hangar.
Aircraft hangars are intended to be classified as Group S-1 occupancies. All
aircraft hangars are to be located at least 30 feet (9,144 mm) from any public
way or lot line, providing adequate spatial separation for neighboring areas. It
should be noted that the measurement is taken to the nearest point of any public
way, not to the centerline as typically applied. Otherwise, their exterior walls must
have a minimum 2-hour fire-resistance rating. Because of the concerns about
below-grade spaces under any facility where flammable and combustible liquids
are commonly present, the code requires the hangar floor over a basement to be
liquid and air tight with absolutely no openings. Floor surfaces must also be
sloped to allow for drainage of any liquid spills.
412.4.6. Fire suppression.
In order to minimize the fire hazards associated with aircraft hangars, fire
suppression is required based on the criteria of Table 412.4.6. The table
determines the hangar classification (Group I, II, or III) to which the fire
suppression must be designed in accordance with NFPA 409, Aircraft Hangars.
The classification is based on the hangar's type of construction and fire area size.
Fire area size is based on the aggregate floor area bounded by specified fire
separation elements that have a fire-resistance rating in accordance with Section
707.3.10. For the purposes of hangar classification, ancillary uses located within
the fire area are not required to be included in the fire area size provided they
are separated from the aircraft serving area by minimum 1-hour fire barriers. See
Figure 412-1.
Figure 412-1. Aircraft hanger fire area.
412.6. Aircraft paint hangars.
The hazards involved with the application of flammable paint or other liquids
cause aircraft painting operations to be highly regulated. Where the quantities of
flammable liquids exceed the exempt quantities listed in Table 307.1(1), such
hangars are classified as Group H-2 occupancies. They must be built of
noncombustible construction, provided with fire suppression per NFPA 409, and
ventilated in the manner prescribed by the IMC. Where the amount of flammable
liquids within the hangar does not exceed the maximum allowable quantities set
forth in Table 307.1(1), the classification is most appropriately a Group S-1
occupancy, and the provisions of this section do not apply.
412.7. Aircraft manufacturing facilities.
The traditional travel distance limitations have always been considered somewhat
problematic for expansive aircraft manufacturing facilities without incorporating
exit passageways or horizontal exits into the building's means of egress system.
Due to the compartmentalized nature of horizontal exits, they do not lend
themselves to aircraft production processes or movement of the completely
assembled aircraft. For similar reasons, exit passageways are generally installed
below the floor of the manufacturing level. The use of underground passageways
during a fire event or other emergency in such a large, high-volume space is
widely viewed as generally contrary to human nature. Once aware of an event,
employees typically evacuate the building instinctively at the level with which
they are most familiar. It is also relatively common for occupants to want to move
away from the point of origin of a fire due to a person's sensory awareness within
the entire open space. Given the fact that occupants sense safety as they move
away from a fire incident, it is counterintuitive to enter an underground area
unless as a final resort.
In spite of these observations, it is important that it can be demonstrated that
such large-volume spaces are able to provide a tenable environment for the
evacuation or relocation of building occupants. The increased travel allowances
established in Table 412.7 are supported by smoke and temperature fire
modeling conducted using the National Institute of Standards and Technology Fire
Dynamics Simulator computer program. Results of the fire modeling activity,
based on conservative assumptions, were used to establish the maximum travel
distances provided.
The travel distance allowances for aircraft manufacturing facilities are therefore
based on a combination of building features: the minimum height from the
finished floor to the bottom of the ceiling, roof slab, or roof deck above; and the
contiguous floor area of the aircraft manufacturing facility having the indicated
height.
Ancillary spaces within or adjacent to the manufacturing area are permitted to
egress through the manufacturing area having a minimum height as established
by Table 412.7. The portion of travel within the ancillary spaces is limited to the
general travel distances set forth in Table 1017.2 based upon the occupancy
classification of the ancillary space. The overall travel distance cannot exceed the
distance indicated in Table 412.7.
412.8. Heliports and helistops.
Helistops are differentiated from heliports by the presence of refueling facilities,
maintenance operations, and repair and storage of the helicopters; thus, helistops
pose similar hazards to those posed by aircraft repair hangars. The minimum size
of a helicopter landing area is addressed, as are requirements for construction
features and egress. Where heliports and helistops are constructed in compliance
with the provisions of this section, they may be erected on buildings regulated by
this code.
Citation
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The International Code Council® (ICC®); Douglas W. Thornburg, AIA, C.B.O.; John
R. Henry, P.E.: 2015 International Building Code® Illustrated Handbook. Aircraft-
Related Occupancies, Chapter (McGraw-Hill Professional, 2015),
AccessEngineering
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