Hmm, not sure that everyone here is talking the same talk. I have had a bit of a look at the Aussie regs and situation and think I have an answer....
Drift downs are not an all engines inop situation. They are a terrain clearance procedure in the event of one inop in the enroute section of a flight
Drift downs are called for by the Australian regs in CAO 20.7.1b, which is the performance criteria for heavy metal -- takeoff, enroute, missed approach and go around performance in the all engines and one or two inop situations.
Basically, if portion of a flight will be conducted in an area where the LSALT/MORA/MSA is HIGHER than the one inoperative ceiling of your aircraft, you can still fly that route segment provided that should you lose a donk at the most inconvenient point, your DESCENT ANGLE will be such that you will be able to continue/double back/fly an escape track to an area where the LSALT/MORA/MSA is AT or BELOW the one engine inoperative ceiling.
This suggests to me that we fly a higher speed than a minimum descent RATE speed - how about a minimum descent ANGLE speed, like a best L/D speed?
A minimum RATE would perhaps be applicable if (1) we had stuffed it up and recklessly flown over an area where the LSALT was above one inop ceiling (2) we were not concerned about terrain clearance and wanted to maximise time before impact, such as preparing a cabin for emergency landing or ditching. That would be an
emergency rather than an
abnormal situation, perhaps an all engines inop situation (fuel starvation/exhaustion) instead of just one or more inop
Agree? Disagree? What did he say
