grow45
14th Jul 2005, 17:42
I've been doing a fair bit of flying with FlyBe on the Q400 recently but have only just realised that the safety brief does not include use of oxygen masks. Presumably this is because at a cruise of 23,000ft you can get below 10,000ft in a a very short time so they are deemed not to be needed but would be interested to have this confirmed.
Also what would the max rate of descent used in such an situation be.
Thanks
g45
Dash-7 lover
14th Jul 2005, 18:36
To give you an idea, for the -300 assuming the structural integrity of the aircraft is ok then the max rate of decent from FL250 with the power levers at Flight Idle and Condition Levers at MAX is, I think 214kts (Vmo - max operating speed), then you must reach FL140 in 3 minutes, which I believe is the limit. Hence no oxygen masks. I do believe they're optional as some operators take them out to save weight (including the APU). Obviously crew oxygen supplies are always carried.
If structural integrity is in doubt then rate of decent is limited to 190kts, or if you're at FL180 or less then a decent of 2000ft per minute is sufficient.
That's my limited understanding......not sure about the Q400 though.
Wycombe
14th Jul 2005, 21:29
Believe the ceiling without pax oxygen is FL250