- A rapid loss of cabin pressure at the most critical point followed by a descent to a safe altitude as defined by oxygen availability.
- A rapid loss of cabin pressure and a simultaneous engine failure at the most critical point followed by a descent to a safe altitude as defined by oxygen availability.
- An engine failure at the most critical point and descent to one-engine-inoperative cruise altitude and diversion at one-engine-inoperative cruise speed.
So,I think reading the scenarios individually word by word there may be a difference between what the regulations require and how you would actually operate the aircraft.
Clearly in 1 you could actually be at LRC speed and be able to stay quite high depending on the supplementary oxygen you have in addition to the regulatory minimum. I'm always thinking FL140/FL100 but technically could be higher depending on the excess oxygen in addition to the minimum.
In scenario 2 it actually says "followed by a descent to a safe altitude as defined by oxygen availability". So the descent is defined again by oxygen availability with no mention of OEI drift down alt. (Clearly in real life you would have to descent to the most limiting altitude but for the purpose of this regulatory critical fuel it doesn't say that!). So here is a scenario where you may be OEI LRC but held high due to supplementary oxygen similar to above.
In 3 it stipulates descent to OEI drift down at OEI speed.
I can now see in a particular set of circumstances dictated by any terrain escape routes, aircraft type etc that 1+2+3 will all vary and there may be an odd case where 2 is not indeed the highest value.
Thats my take anyway.