engines, fuel loads, wingspans, and other key parameters, an envelope must be created to
conservatively encompass these parameters. While it would be convenient to simply provide a
composite aircraft, this could prove to be wildly conservative in many cases. Therefore, some
judgment will be required. Specific guidance cannot be provided because of the multitude of
possible situations, but some of the critical parameters to consider are given below as
If certain aircraft types within a subcategory are not expected to be using the airport,
they should be eliminated from consideration. For example, if an airport has
commercial flights but is not suitable for wide-body aircraft, these aircraft would not
need to be considered in developing the representative aircraft.
Aircraft types that are clearly less damaging than others within the subcategory do not
have to be specifically considered. For example, if a large twin engine jet and a small
twin engine turbo-prop both use an airport, it is permissible to state that the large
aircraft bounds the smaller aircraft with respect to the structural response of the target.
Do not feel constrained to pick a particular existing aircraft type to represent a
subcategory. Features of various aircraft types (e.g., the fuel load of one type, the
engine mass of another type, the number of engines of a third type, etc.) can be
combined into a surrogate representative aircraft.
Do not feel constrained to use only one representative aircraft. If certain parameters
cannot be enveloped by a single representation, multiple structural response
calculations may be performed. For example, if one type of aircraft has wing mounted
engines and another has tail mounted engines, it may not be obvious which one will
cause the most damage. In this case, the damage can be assessed for both and the
worst case used for release scenario development.
Whatever representation is used, the basis for the assumptions that led to that selection must
be fully documented.