Escape routes, oxygen requirements

[SG73x]

Hi,

I am interested in understanding the use of escape routes while flying over extensive areas of high terrain (e.g the Hymalyas).
Searching this forum, I read that in case of loss of pressurisation, you would have to descend to the MEA if it's higher than 10'000ft... as an example let's say it's at 18'000ft.
You would then need an escape route that will allow you to descend to 14'000ft prior to exhaustion of the oxygen supply system, and then further descend to 10'000ft within 30min after (please correct me if I am wrong).

1. Why 14'000ft initially ? Does it have to do with EASA supplemental oxygen requirements ?

2. In case of an engine failure, or a fire onboard, would you use the same escape route or are there other "types" ? I am assuming that engine out is less critical in terms of time and altitude.

3. What about cargo flights ? Are supernumaries considered as pax with the same type of oxygen system ?

4. Typically, how many escape routes would be planned if flying near the Hymalyas (routes like LHR-HGK)

5. Are escape routes published anywhere, or are they developed by airlines ?

Thank you for your answers.

[casablanca]

I’ll attempt to answer few questions by memory.....which is not very scientific!
On the 777 there were some escape routes in Himalayas that we had that initially descended Fl 270, then 240, then 180,then 140 finally, so depends on options and terrain- if your aircraft didn’t have the extra required O2 different routing required

normally freighter Ac, have class E upper deck cargo compartments....with no real fire suppression other than descent to Fl 250 and depressurization to try and starve fire of O2.........so O2 required was for pilots and supernumeraries to fly at fl250 for 2 hours? and supernumerary had same type of bottled oxygen

[wiggy]

Can’t comment on the specifics of the Himalayas but I’ll offer the following:



1. Why 14'000ft initially ? Does it have to do with EASA supplemental oxygen requirements ?


As a general point the 14000’ might be airline specfic...we use an initial default 15000’ or the MEA whichever is higher, regardless of where we are in the world, whether an escape route is “in play” or not..we would then try to carry on the descent to 10000 as soon as possible but other factors can come into the equation such as range to alternate.....for example if the depressurisation occurred the middle of an ETOPS segment over the ocean then despite the lack of terrain a descent to 10k might not be possible for quite some time.

2. In case of an engine failure, or a fire onboard, would you use the same escape route or are there other "types" ? I am assuming that engine out is less critical in terms of time and altitude.

Where we are the documentation will give the escape route for a depressursation, and then state, what if any escape route is needed for an engine failure. Typically for us single engine cruise would be above 20000’ so you are right in saying the engine out might be slightly less critical.

5. Are escape routes published anywhere, or are they developed by airlines ?
.

Ours are produced by the airline and are contained in the aircraft performance manual (since performance and oxygen equipment/provision varies by customer specification, aircraft type and variant within that type).