Rapid Depressuriation and use of oxgen masks
 

Discussion during an overnight. Seems different airlines have different policies with regard to the donning of crew oxygen masks as part of the Cabin Altitude Warning or Rapid Depressurization.

Keeping in mind the time of useful consciousness at typical airliner high altitude cruise altitudes, some operators require that both pilots immediately and simultaneously don their oxygen masks regardless who is PF or PM.

Another point of view is that the PF hands over control to the PM and dons his oxygen mask while the PM continues to monitor the flight path. Once the PF has his mask on, he takes over control while the other pilot then dons his own mask. Crew communications are established next. The principle being one crew member looks after the flying rather than both pilots donning their masks simultaneously leaving no one looking after the flight path even for the theoretical few seconds it should take to don their masks and establish comms.

Realistically, since the probability of the autopilot being engaged at high altitude cruise is the norm, it should be perfectly safe and highly desirable that both pilots simultaneously don their masks. But to leave one pilot off oxygen for any amount of time (for the claimed reason of watching the flight path) while the second pilot dons his mask first, would appear to be unwise, in view of the time of useful consciousness that could be less than ten seconds.

Your views appreciated.

Even if the autopilot disconnects due to one or other reason during the rapid depressurization, the aircraft should be trimmed, so no significant deviation from flight path would occur. It doesn't take even 10 seconds to take the mask on (without the headset) and even if aircraft goes into 3000ft/min climb/descent for some reason, you will still be (in worst case scenario) 500ft from your originial altitude, so still 500ft separation if traffic is immediately below/above you.

In my opinion, during the rapid depressurization there are only three steps that have to be done ASAP: mask on, check oxy regulator is at 100% and establish communication. Then you have time to do couple of deep breaths and proceed with the required actions.

If the first pilot fumbles putting on his mask while the second waits...

I'd rather both go for survival first. At altitudes where O2 is required, it'll take a few minutes for the plane to hit the deck. George can wait a few seconds.

Why do people need to make it so difficult? The memory items state don masks, it doesn't say take turns doing the masks.

It does however say in the QRH that one person takes off their mask first....

The masks are designed to be put on within 5 seconds.

John_smith I concur. Useful consciousness at high altitude is in the seconds.

Definately both don masks asap! Its the removing of masks that would be recommended to be in turns.