Certification and practice mismatches

[Genghis the Engineer]

Just something I've noticed once or twice, and I wondered if anybody had any other examples.

Stalling: certification is done at 1kn/s deceleration, but in many cases flying instructors teach using a much higher deceleration rate so that they can get a better stall pitch break during stalling demos. [Also the hopefully now dead issue of "powering out of the stall" which EASA and FAA clamped down on a few years ago.]

Airliner evacuations: aeroplanes are always certified using "step and slide", whilst many airlines practice the slower "sit and slide".

Grumman AA5 (happens to be a favourite aeroplane of mine): POH uses flapless take-offs, whilst most experienced pilots on type will use 1/3rd flap for short field take-offs.


Can anybody think of any other differences out there between how an aircraft is certified, and how it's subsequently operated?

G

[john_tullamarine]

.. the list goes on and on .. the two groups have a long standing practice of doing their own thing ... and rarely the twain shall meet.

OK .. a bit of an exaggeration but you get the idea. Been a problem since long before I first got myself into an aerodyne.

[safetypee]

G, I would expect to find a gap in most areas that are considered, the problem is if the gap is widening and is this significant. jt :ok:

Aircraft certification provides a ‘yardstick’ for comparing aircraft, but the measure increasingly lags operations.
The process is (was) consistent, where interpretations would be recorded and applied elsewhere.

Operational regulation is more diverse, and whereas a small self-contained authority (cert / ops) would talk to each other, this is now less apparent in today’s vast bureaucracies; this is where the gap originates.
Operations involve man and machine (and social environment) which are much more difficult (impossible) to contain, yet many authorities try to apply the certification ‘yardsticks’ as a control, but without the necessary understanding of how or what the measure involves.
Operational and commercial pressures demand work closer to the boundary of safety. In the absence of hard operational limits, aircraft regulations are use with the risks variable and inappropriate application.
e.g. using the aircraft certification evacuation limit, 90sec, for operations; how then might operators manage the variations in human performance and situational demands in the real world - limits cannot be a norm.

The problem could be considered like some modern views of safety re work as imagined vs work as done … finding the gap.
Is this gap significant; in many areas yes and increasingly so. Whereas aircraft fail we fix them / change regulation, modern operations involve diverse failures less amenable to being ‘fixed’ or contained by regulation.
Aircraft design and construction can be related to certification regulations (part 21, 25, etc); where is the book for those who design / construct the human.

Instead of attempting to write the ‘human book’ by looking at past failures, consider redefining the operational system – design and construct the operating environment we wish to fly in. However, this is unlikely as long as the (operational) industry continues to try to fix the past, opposed to looking forward to creating a more optimal operational environment.

[john_tullamarine]

In essence, from my simplistic view of life, the operational regulators need to do what they must to meet real world needs .. BUT .. with an appropriate eye on the certification ins and outs to ensure that the operational requirements imposed remain conservative with respect to the certification constructs.

Often one observes circumstances where this isn't done terribly well ...