A184.108.40.206.2. Low-Impact Resistant Support -- A support for elevated fixtures or other devices
designed to present a minimum mass and to break with a minimum resistance when impacted.
Normally used for supporting lights or other devices between 2 meters and 12 meters (6 feet
and 40 feet) above the mounting surface.
A220.127.116.11.3. Semi-frangible Support -- A two element support for light fixtures or other
devices designed for use in applications where the mounting height is over 12 meters (40 feet)
above the ground or the facility or device is constructed over a body of water. These type
supports are comprised of a rigid base or foundation with a frangible or low impact resistant
support used for the upper portion of the structure. The rigid portion of the structure must be
no higher than required to allow performance and maintenance of the apparatus and the
frangible or low impact resistant support.
A18.104.22.168. New designs for airfield equipment, systems, and other facilities must meet the
following guidelines for acceptance as a permissible deviation. These requirements do not apply to
facilities that house people.
A22.214.171.124.1. Frangible structures - Construction above the ground surface that will collapse or
shatter upon impact. The structure must be designed using materials of minimum mass that will
either break into segments or shatter without impaling the aircraft skin or becoming an obstacle
to the continued movement of the aircraft.
A126.96.36.199.2. Frangible Support - Used for mounting fixtures or equipment items less than two
meters (six feet) in height. The structure will be of minimum mass and will separate at the base
connection when struck by a moving aircraft. Upon separation of the base connection, the
support must not alter the path or impede flight of the aircraft if a segment of the structure
wraps around the aircraft. The structure also must not impale itself in the aircraft
A188.8.131.52.3. Low-Impact Resistant Support - Used for supporting elevated fixtures or
equipment items more than two meters but less than 12 meters (6 to 40 feet) above the ground
surface, typically towers or poles. Upon impact by aircraft, the structure will be designed to
break away at or below the impact location and collapse without wrapping around the aircraft,
impaling itself in the aircraft, or causing significant structural damage to the aircraft. If the
design is such that potential exists for a portion of the structure to wrap around the aircraft, it
shall not significantly alter the path or flight trajectory, nor prevent the aircraft from completing
a successful takeoff or landing. Collapse of the structure may occur at a single point of failure
or may be a segmented collapse. The structure shall be designed such that service of the
equipment must be accomplished by lowering the equipment. The design shall not include
elements that permit climbing by means of a built in ladder or other scaling devices.
A184.108.40.206.4. Semi-Frangible Support Semi-frangible supports are used for those elevated
fixtures or equipment items that must be higher than 12 meters (40 feet) or constructed over a
body of water. The foundation shall be no higher above grade or the surface of the water than
necessary to allow performance and maintenance of the apparatus and the frangible or low
impact resistant support. The upper portion of the structure will be constructed of multiple
elements of low-impact resistant supports. The supports may be in pairs that provide
directional stability or groups that provide stability to the grouping as an element. Upon impact
by aircraft, each of the supporting elements will be designed to collapse as a unit or in segments
independent of the grouping. The elements of the supporting structure will not impale in the
aircraft, wrap around the aircraft, or significantly change aircraft direction of travel upon
impact. If the design is such that potential exists for a portion of the structure to wrap around