UPDATE 12th October 2021: AC 91-02v1.0, Guidelines for aeroplanes with MTOW not exceeding 5 700 kg – suitable places to take off and land, issued in October 2021 answers  the question!

My earlier articles on the performance requirements of Part 91 were based on the draft so, as it is only a few months before it takes effect, we should consider it again. Being a former flight performance engineer, I like to take an interest in numbers so let’s discuss take-off and landing performance as required by 91.795 and 91.800.

We’ll discuss take-off performance in some detail and just touch on the similar landing performance requirements.

Perhaps my opinion is incorrect so I look forward to an Advisory Circular on this subject or other clarification from CASA. Some suggested questions to ask:

  1. The Part 91 MOS 24.02 states “You must determine the aeroplane performance from 1 of the following” then lists the AFM, manufacturer’s data manual or data approved under Part 21. Does this mean that only data from any of those three sources may be used or may other data be used to supplement what is in there? For example, the Piper Archer III POH states “Effects of conditions not considered on the charts must be evaluated by the pilot, such as the effect of soft or grass runway surface on takeoff and landing performance …”.
  2. Will CASA be providing guidance in the form of an AC to include aircraft with an older certification basis, or no certification basis, where the performance information provided is quite sparse? Only aircraft certified to later amendments of FAR 23 were required to provide performance data for all conditions within the operational limitations of the aircraft. Two examples:
    • The 8KCAB Standard Decathlon has take-off performance data provided only for a Sensenich 74DM6S8-0-56 propeller however many examples in Australia have the coarser pitch -60 propeller with worse take-off performance.
    • The 8KCAB Xtreme Decathlon has a limitation of maximum outside air temperature of 49 deg C however airfield performance information is only provided to 40 deg C.

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