how to handle a rapid decompression over the Pacific ?
 

is there any specific procedure for over pacific ocean?
many thanks!

Same as any ETOPS route assuming you mean a twin?

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.

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!

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!

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

• 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

Critical fuel is of course only required, if the calculated minimum fuel is not sufficient for such an event.

Regards,
DBate

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.

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 .

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!

:8

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

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.

Markerinbound:

Not allowed for Part 121 ops.

Two words: Liquid Oxygen. The C-5 had 100 liters, as I remember, the system could supply everyone at FL 240 for almost 6 hours. So, no issues there. Since leaving everyone on masks for that long was a bit inhumane, we planned depressed at FL 100.

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

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.

Is it possible you'd get a slightly better range because of one less engine. Just wondering...

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.

@ReverseFlight:

I was responding to MarkerInbound. My question was whether a ( decompression + lost engine ) be better than just a decompression from range considerations alone.

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.

Yes, for the 737 that is the case.

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.

For us, planned speed is simply that - planned speed to establish the area of operation. There is no need to actually fly at that speed if you had a decompression.

How about this one: lose cabin pressure halfway, and have to descent to 10000 ft into heavy convective weather. I did. Wasn't fun.