This Advisory Circular sets forth an acceptable means, but not the only means, of demonstrating compliance with the provisions of the airworthiness standards for transport category airplanes related to the airplane design for flightdeck (also referred to as the pilot compartment or cockpit) intrusion resistance. Intrusion resistance, in the context of this Advisory Circular , refers to the ability to resist forced entry by a person who is not authorized by the pilot in command to enter the flightdeck. Intrusion resistance also includes the ability to resist attempts to enter the flightdeck through use of simple tools, such as pocket knives, nail files, or keys.
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APPLICABILITY. While these guidelines are not mandatory, they are derived from Federal
[ad] Aviation Administration (FAA) and industry experience in determining compliance with the pertinent regulations. If, however, we become aware of circumstances that convince us that following this Advisory Circular would not result in compliance with the applicable regulations, we will not be bound by the terms of this Advisory Circular , and we may require additional substantiation or design changes [ad]
as a basis for finding compliance. The material in this Advisory Circular does not change, create any additional, authorize changes in, or permit deviations from regulatory requirements
RELATED DOCUMENTS.
a. Title 14, Code of Federal Regulations (14 CFR) part 25, §§ 25.365, 25.771, 25.772,
25.795, 25.809, and 25.853.
b. 14 CFR part 91, § 91.11.
c. 14 CFR part 121, §§ 121.313, and 121.587.
d. International Civil Aviation Organization (ICAO) Annex 8 to the Convention on
International Civil Aviation, titled “Airworthiness of Aircraft.”
e. Policy memorandum PS-ANM100-2001-115-11, Certification of Strengthened
Flightdeck Doors on Transport Category Airplanes, dated December 3, 2002, available at:
http://rgl.faa.gov/1
5. DEFINITIONS.
a. Bolt: A bar which, when actuated, is moved (or “thrown”) either horizontally or
vertically into a retaining member, such as a strike plate, to prevent a door from moving or
opening.
b. Cylinder: The cylindrical subassembly of a lock, containing the cylinder core, tumbler
mechanism, and the keyway.
c. Door Assembly: For the purposes of this AC, a door assembly consists of the following
parts: door (including any and all panels and mechanisms intended for decompression and/or
egress purposes); hinges, locking or other devices; operation contacts (such as handles and
knobs); miscellaneous hardware and closures; the frame (including the header and jamb
structures plus the attachment to the surrounding airplane structure); and representative structure
to which the frame attaches.
d. Flightdeck Boundary: Any of the features that divide the flightdeck from the areas of
the airplane occupied by passengers. It could be a vertical wall (e.g., a bulkhead), floor, ceiling,
a monument whose structure makes up part of the boundary, or any combination of these. It
includes the flightdeck door. An accessible flightdeck boundary is one whose location provides
direct access to the flightdeck by passengers.
e. Jamb: The fixed vertical members of a doorframe to which the door is secured.
f. Jamb/Strike: The component of a door assembly that receives and secures the
extended lock bolt. The strike and jamb, used together, are considered a single unit.
g. Jamb/Wall: The component of a door assembly to which a door is attached and
secured by means of hinges. The hinges and jamb, used together, are considered a unit.
h. Latch (or Latch Bolt): A beveled, spring-actuated bolt.
i. Lock (or Lock Set): A keyed device (complete with cylinder, latch and/or an electrical,
pneumatic or mechanical means of preventing normal operation, strike and trim such as knobs,
levers, escutcheons, etc.) for securing a door in a closed position against forced entry.
j. Strike: A metal plate mounted to the jamb to receive and hold the latch bolt in order to
secure the door to the jamb.
1 Select Policy, select Final, and search for ANM100-2001-115-11.
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6. DISCUSSION.
a. Background.
(1) When a passenger gains unauthorized entry to the flightdeck, the safety of the
airplane and all aboard is at risk.
(2) The flightdeck door is subjected to several requirements that affect its construction.
For example, §§ 121.313 and 121.587 require that there be a lockable door between the pilot and
passenger compartments and that the pilot-in-command ensures that the door is closed and
locked during operation.
(3) Section 25.772 requires that the pilot compartment door has features that allow the
crew to directly enter the passenger compartment from the flightdeck in the event that the door
becomes jammed. If there are passenger emergency exits in close proximity to the flightdeck,
compliance with § 25.809, “Emergency exit arrangement,” can be shown using a method in
which the flightdeck openable windows need not be openable from the outside. In this case, the
door needs to facilitate entry by rescue personnel.
(4) Many airplanes are designed to utilize the flightdeck door opening as a
decompression pathway to demonstrate compliance with the requirements of § 25.365.
Therefore, the locks and/or other features may be designed to allow for extremely rapid opening
times.
(5) Due to the fact that § 25.777 requires that the flight controls be designed for pilots
from 5 feet, 2 inches to 6 feet, 3 inches in height, consideration must be given to these statures in
complying with the egress requirements of §§ 25.772 and 25.809.
(6) Considered a part of the airplane interior, the flightdeck boundary must also meet
the requirements of § 25.771 with regard to noise, light and odors, and the flammability
requirements of § 25.853.
(7) All of these requirements continue to apply, and the flightdeck door and other
boundary assembly designs must consider their impacts.
b. Vulnerability.
(1) Due to the previously referenced regulations, the flightdeck door was historically
designed to prevent only unintentional and incidental entrance into the crew compartment and
not that of a determined person. The loads required to overcome the locking mechanisms
typically are much lower than the loads on the flightdeck door caused by kicking or ramming the
door assembly. Features of the door, such as hinges and locking mechanisms, should not be
easily overridden (e.g., by insertion of a credit card or prying). The door knob is also susceptible
to pulling force and should be designed to limit the ability of a person to exert high loads (e.g.,
by shape and the use of frangible features).
(2) The remainder of the flightdeck boundary elements are generally considered less
vulnerable than the flightdeck door but should satisfy the same standards. The bulkhead
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separating the flightdeck from the passenger cabin has inherent structural capabilities that should
satisfy the intrusion resistance requirements. Intrusion tests may not be necessary in most cases.
On multi-deck airplanes, the floor and/or ceiling of the flightdeck may also be affected, although
the ceiling might be high enough that it would not be considered “accessible” for the purposes of
intrusion resistance compliance. A boundary is accessible if it could be exposed to loads from
attempts at forcible intrusion. If the flightdeck bulkhead is either composed or installed forward
of other interior structures, such as a galley or closet, the contribution of those interior structures
(and any space between them and the bulkhead) to intrusion resistance may be included when
assessing the acceptability of the boundary.
(3) Although the flightdeck door (along with other boundary elements) is intended to
resist forced entry, it is only one element of several in-flight security measures that work in
conjunction with one another.
c. Tests.
(1) The tests described in this AC apply to all elements making up the flightdeck
boundary where testing is required. The various types of flightdeck door designs (see Figure 1
for examples) will likely require the most testing.
(2) The goal of the tests discussed in this AC is to demonstrate that the flightdeck door
and other elements making up the flightdeck boundary can resist the unauthorized entrance of a
person.
(3) Features of the door (such as telescoping panels, Dutch panels, and removable
panels, as shown in Figure 1) that are designed to comply with, or to aid in compliance with,
decompression or egress requirements do not require testing if their failure would not
appreciably degrade the intrusion resistance offered by the flightdeck door. If this cannot be
shown, testing will be required. Similarly, features of the other boundary elements should be
reviewed for their effect on intrusion resistance if they were to fail under intrusion loads. Such
features should be tested when the review indicates that the failure would negatively affect
intrusion resistance.
(4) With respect to intrusion resistance, the size and location of a movable panel are
the key factors in determining whether or not it affords intrusion resistance. Panels that are small
and are located at the extreme bottom or top of the door are typically less vulnerable to intrusion.
An example of a design feature that could also address ballistic protection is shown in Figure 2
