how to handle a rapid decompression over the Pacific ?
Joined: Jul 2011
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From: Somewhere
You have to breathe...so you either have the O2 system to stay up there at alt, providing for you and pax, or you come down to an alt where you the O2 system can provide for you and pax, or you come down to an alt where you can now breathe ambient air...What ever alt you end up at, to breathe and not be a pilot Popsicle, now you have to consider your new fuel burn, that if planned for, you can make to your destination.
Can your average airliner leaving LAX, once hitting the half way point, continue at alt providing O2 for everyone or do they have to come down and now have enough fuel at the lower ALT to make it to Hawaii.
It's a loaded question and I would really love someone to show me how 150 passengers could be provided 2.5 hours worth of O2 at 39000 feet.
Can your average airliner leaving LAX, once hitting the half way point, continue at alt providing O2 for everyone or do they have to come down and now have enough fuel at the lower ALT to make it to Hawaii.
It's a loaded question and I would really love someone to show me how 150 passengers could be provided 2.5 hours worth of O2 at 39000 feet.
Thread Starter
Joined: Mar 2005
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From: Asia
Both ETOPS or non ETOPS flight. even 4 eng aircraft as well.
Generally "descend to 10,000ft or MSA whichever is higher and land at the suitable airport ASAP."
But I just wonder any specific procedure and considerations for when I fly over the pacific ocean.
Thanks again!
Generally "descend to 10,000ft or MSA whichever is higher and land at the suitable airport ASAP."
But I just wonder any specific procedure and considerations for when I fly over the pacific ocean.
Thanks again!
Joined: Jun 2005
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From: USA
Masks on, throttles idle, nose down with an offset turn, emergency descent checklist. Make the required radio calls. Level off at the altitude planned for this contingency at the appropriate lateral offset distance. Establish planned contingency airspeed and course appropriate for contingency destination. Notify ATC as required. Hope and constantly check that your contingency fuel planning was adequate.
Hopefully your pre-flight review of the contingency planning leaves you with some modicum of confidence in your new prospects!
Hopefully your pre-flight review of the contingency planning leaves you with some modicum of confidence in your new prospects!
Joined: Jan 2003
Aviation Qualifications: ATPL
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From: Europe
Considering the fuel requirement for such an occasion: Additional Fuel (called critical fuel at our outfit for such a case) should be carried on such a flight:
Critical Fuel is the fuel required at the most critical point along the routes, if a loss of one or two engines or loss of pressurisation occurs, to
Regards,
DBate
Critical Fuel is the fuel required at the most critical point along the routes, if a loss of one or two engines or loss of pressurisation occurs, to
- descent according to procedure and continue with LRC to a suitable AD and
- hold there for 15 min at 1.500' AAL
- and make an approach and landing
Regards,
DBate
Joined: Nov 2007
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From: Texas
We had three fuel calculations on the paperwork OAK-HNL.
1. How much fuel we needed to fly the leg plus alternate and reserve - almost irrelevant except to plan a landing weight.
2. How much fuel we needed to get to the ETP, lose an engine, drift down and keep going in the middle 20 thousand levels.
3. How much fuel we needed to get to the ETP, decompress, dive to 10,000 and press on with all engines.
Number three was always the highest number. If we decompressed AND lost an engine I think we had a wet footprint in the middle.
1. How much fuel we needed to fly the leg plus alternate and reserve - almost irrelevant except to plan a landing weight.
2. How much fuel we needed to get to the ETP, lose an engine, drift down and keep going in the middle 20 thousand levels.
3. How much fuel we needed to get to the ETP, decompress, dive to 10,000 and press on with all engines.
Number three was always the highest number. If we decompressed AND lost an engine I think we had a wet footprint in the middle.
Joined: Jun 2000
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quote "I would really love someone to show me how 150 passengers could be provided 2.5 hours worth of O2 at 39000 feet. "
low level fuel burn and resultant range is but one question posed by a depress burn. Those of you thinking of staying high to reduce resultant fuel burn (forgetting the pesky pax down the back and their O2 requirements) are not considering the very real danger of nitrogen coming out of solution in the bloodstream / joints .
low level fuel burn and resultant range is but one question posed by a depress burn. Those of you thinking of staying high to reduce resultant fuel burn (forgetting the pesky pax down the back and their O2 requirements) are not considering the very real danger of nitrogen coming out of solution in the bloodstream / joints .
Joined: Feb 2005
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From: flyover country USA
Is there any situation for a 3 or 4 engine a/c where at FL100, greater range can be had with an engine shut down? I propose this based on the fact engines are optimized for cruise @ FL300 and up, and thus run at very low disoptimized thrust at low altitude; SFC is thus higher.
Might be better to run fewer engines at higher thrust!
Might be better to run fewer engines at higher thrust!
Joined: Dec 2002
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From: Where the Quaboag River flows, USA
Barit1
I'm sure there are, the P-3 patrol planes did it regularly. But, I doubt you could do it in public transport. The data is unlikely to be available to determine when an engine shutdown would be advatageous.
GF
I'm sure there are, the P-3 patrol planes did it regularly. But, I doubt you could do it in public transport. The data is unlikely to be available to determine when an engine shutdown would be advatageous.
GF
Joined: Sep 2002
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From: La Belle Province
Nimrod also routinely shut down 2 of 4 for low level patrol IIRC. But redundancy calcs are predicated on keeping as many engines running as you can. No-one's going to encourage commercial pilots to shut down a healthy engine.
Joined: Dec 2002
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From: Where the Quaboag River flows, USA
It's a loaded question and I would really love someone to show me how 150 passengers could be provided 2.5 hours worth of O2 at 39000 feet.
In my corporate operation, like 121 ops, we have to have a dry footprint at FL 100, depressed or dry footprint OEI at OEI optimum cruise level. Have to inquire about OEI and depressed. I suspect on most routes, it is possible.
My most challenging sector was Petropavlovsk to Taihiti, had to fly LRC to make dry prints between Christmas and Taihiti and then just barely when depressurization was planned for. Russian exit points really fouled that one up.
GF
Joined: Nov 2007
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From: Yellow Brick Road
Question: Why does the descent have to be at max speed ? Why risk a structural overspeed instead of a low-speed stall ? Surely the RoD is more important to get down to 10,000' asap ?
e.g. A320 QRH Emer Descent : "Descend at the max appropriate speed."
e.g. B737NG FCTM Rapid Descent : "Target speed MMO/VMO".
Explanation appreciated.
e.g. A320 QRH Emer Descent : "Descend at the max appropriate speed."
e.g. B737NG FCTM Rapid Descent : "Target speed MMO/VMO".
Explanation appreciated.
Joined: Nov 2007
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From: Yellow Brick Road
ross, in case you were responding to my post, I was referring to a rapid decompression over the Pacific (the original subject of this thread) assuming both engines running, therefore OEI and terrain issues are irrelevant. Perhaps I didn't make myself clear.
Joined: Aug 2005
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From: fl
Regululations would not allow an airliner to cross the Pacific and not have a procedure to land at destination or return without everybody alive. We had a rogue chief pilot that wanted to fly from LAX to HNL with no supplemental oxygen even though we had the space. I refused and told the company why I wouldn't do it because ditching was the possible outcome. Common sense will prevail in these matters.
Joined: Jul 2011
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From: Al's Diner
Is it possible you'd get a slightly better range because of one less engine. Just wondering...
If you look at the long range cruise tables at 10,000'. Fuel Flow is about 10% more for the 2 engine case.
Our company works on decompression (2 engine) as the most fuel critical scenario for ETOPS planning. They don't use LRC as the speed schedule, but the result is the same - decompression (2eng) is more limiting.
Establish planned contingency airspeed
