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'Whenrealityisapain.... what would you do if you couldn't descend to a low enough altitude for normal breathing, would you increase the amount of oxygen on-board, and if so, how?
Mutt ------------------------------------ Yeah Mutt, I forgot about the alien force field that prevents aircraft from flying down to 12,500 feet over the Pacific. I'll try to plan for that on my next Hawaii trip. :rolleyes: |
Whenrealityhurts: no civil airliner that I have ever heard of has had a passenger pressure feed O2 system which would be necessary above 30,000ft. Therefore an emergency descent is always required. Some carriers do indeed carry extra O2 supplies if their routes involve very high enroute MSAs and these will usually be in the low 20s or high teens. Not a situation that the original poster asked about. The only other situation that I have come across is the case with all freighter aircraft which may have depressurisation procedures at the mid twenties in order to fight on board fire.
I guess you already knew all this ? !.............. |
M -
In corporate we can feed 02 to the pax for a couple of hours, stay up and altitude, get the fuel burn. It's stating the obvious that if you can't feed 150 pax with O2 for the last thousand miles to Hawaii, then you need enough fuel to fly 1000 miles, in say a 737, at 12500 feet, after having flown a couple of hours to the half away point already. The question was whether an airliner actually had that kind of fuel reserve or not...because given all the stupidity of hiring ab initios pilots, Flex departures, 30000 hour trend monitored engines...it just wouldn't have surprised me if those that planned the trips were just hoping that a depressurization event happened inside of 500 nm of an airport, and that thousand miles in the middle, that one hour window, was just a chance they are willing to take. No one here has given me the numbers, and I don't expect to get them from pilots who haven't planned a trip in an airliner, as dispatch does that. It a catch 22 to ask an airline pilot how much the fuel burn of a 737 is at 12500 feet, if after 2.5 hours of flying at alt, he has the reserves to continue or get out the life rafts. I honestly don't think most of these guy know. If they want to prove me wrong, they can supply the numbers for me to verify. I don't see that happening, they will just say that dispatch has ETOPS, call it good, and blindly point the plane East hoping the tapes don't bottom out on the way there. When you hire guys that are not supposed to ask questions, it's fitting that your not going to get guys that go home and run the numbers and see if they are right. |
WRH
Clearly, you have never seen a computer flight plan for an overwater leg. It is all spelled out for CPs--depressurization, OEI and medical diversions. Fuel burn to CP, Fuel remaining, drift down plan, distances, winds, times and fuel remaining, all planning required. NOBODY coasts out on a guess. I've done many legs with, as many 9 critical points on a CFP by Jeppesen. Petro to Tahiti is one, Honolulu to Koror is another. In corporate, we don't "stay up and get the fuel burn", we descend to FL100 and divert, as planned. Yes, we have good oxygen supply, but I don't wish to expose the passengers to using oxygen out of constant flow masks for hours, nor expose them to physiological problems at high altitude. Having crossed to HI at lower levels there is no likelihood of problems at FL100 As usual, you are posting your ignorance of airline, military, corporate operations and apathy as to learning more. In military, airline and corporate, I've used reduced power, on condition maintenance, the list goes one, all very successfully. GF |
wrh - as we suspected, you have no idea and as I said you are wasting our time. As for "In corporate we can feed 02 to the pax for a couple of hours, stay up and altitude, get the fuel burn." - I just cannot believe it! You would have law suits coming out of your ears (assuming you are still alive, of course). Leave ETOPS to the professional pilots. Back to the PC would be best?
the tapes don't bottom out on the way there. |
I'll try to be polite,
Our planning system sounds similar to the one Galaxy Flyer describes. It compares the following three cases and ensures that we always have fuel to divert to the nearest available and suitable alternate in any of the following three cases: 1. Total pressurisation failure, followed by 2 Eng div at 15000'. 2. Engine failure and pressurisation failure, followed by SE div at 15000' 3. Engine fail, drift down, and single engine div. It's very rare that we see extra fuel added to fill any shortfall at the critical point, that usually happens if you're heading West out of Europe over the mid Atlantic to, e.g. the Caribbean.....BWTF do I know.... It a catch 22 to ask an airline pilot how much the fuel burn of a 737 is at 12500 feet, if after 2.5 hours of flying at alt, he has the reserves to continue or get out the life rafts. |
And, I might add, cockpit procedures to monitor current fuel burn, estimated fuel at the CP(s), weather at the alternates via SATCOM and an in- cockpit plan, if any parameter is heading south. I operate corporate, so I don't have Dispatch watching all this, but we do "re-write" the plan, if fuel burn is not meeting the planned burns (almost never happens, tho)
GF |
WRT: do you understand the difference between crew O2 systems and those supplied to the passengers AND the reason for these different systems? Your posting suggests a lack of understanding on your part.
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Gentlemen, let's recap...get you all back on track..
You've passed the half way point from say LAX to HNL...you have lost pressurization, you've dropped down to say 12500...what is your fuel burn at this alt, and how much fuel do you have left to get there. Simple question requires a simple answer.... |
Ah, now you start asking nicely.
I'd love to help but don't fly the 737... |
WRT: Rule of thumb on B747 was - consumption at 10,000ft was 140% of cruise fuel flow. Hence the usual mandatory fuel add on that is required for oceanic flights.
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and I don't expect to get them from pilots who haven't planned a trip in an airliner, as dispatch does that. Even in our part 91 aircraft we know what the fuel flow is at 10,000 feet, together with the ETOPS points, diversion airports and distances...... not required by regulation, but nice to have :):) As for our corporate aircraft, we do not consider continuing at altitude following a depressurization regardless of the amount of oxygen that we have onboard. Mutt |
Actually the 737-800 handles PHNL or any of the island airports quite well and full tanks are not generally required. The 737 in ETOPS opeartions needs to have the APU running from the ETOPS Entry Point to the Exit Point and that fuel burn is part of the ETOPS flight plan. The biggets question is, do you start it and leave it running at the gate, or start it just prior to the Entry point only to find out that it won't start, thus causing a turn back.
I seem to recall that both the DC10-10 and the L1011-1 used a 2EO ETP, not a simple loss of one engine, combined with the decopmpression. Also there were weights that could cause you to dump fuel during the driftdown to somewhere around 6000' ASL, and then as your weight decreased, climbing back up to 10,000 for the balance of the trip. Kinda hairy! You would be surprised how many Boeing aircarft have higher burns at 10,000 with 2 engines running than at 10,000 with 1EO thus making the simple loss of pressurization the #1 Critical Fuel Scenario. |
OK465.
I don't get your numbers, or slang that your using... Give me your 737 Model. Departure fuel in gallons/lbs with 150 pax at 175 lbs+25lb bags. MTOW with departure fuel, pax and bags. Fuel burn at say 370/390, you choose. Fuel Remaining just past the half way point from LAX to HNL Fuel Burn in lbs at 10,000, per hour, time to fly the remaining 1100 nm at ten thousand feet. Thanks... |
Don't sweat it Ok-465...76 posts later no one else in here knows what their airliner burns at altitude either.
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I'm curious, how much MORE information do you think we should have available to us?
EINN/CYYT - EQUAL TIME POINT DATA - ETP1 - - - - - - - - DIVERSION SUMMARY - EINN CYYT TIME 03.01 @ 0290KT F.L. 0099 FOB 017623 G/C DIST 0945 0872 AVG W/C P024 M001 TEMP @ FL099 M005 P000 BURN SUMMARY FL099 ... 1 ENG. 2 ENG. 1 ENG. 2 ENG. 1LE 1LE 1LE 1LE DIVERSION 009917 03.33 009768 009658 009917 009797 HOLD 000583 00.15 000584 000737 000583 000736 MAP 001200 001200 001200 001200 001200 CONSERV. 001394 001375 001338 001394 001355 ICE DRAG 002223 002194 001855 002223 001877 ANTI-ICE 000000 000000 000000 000000 000000 APU 000912 000900 000899 000912 000911 TOTAL 016229 03.48 016021 015687 016229 015876 FOB 017623 QTY DIFF. +001394 DRIFTDOWN SUMMARY DATA CRZ TO BURN FL MSA TO BURN FL MSA FOB LAT LON W LRC*EINN 010176 100 049 CYYT 010290 100 025 017623 N57354 W035138 1LE*EINN 007961 250 049 CYYT 007954 250 025 017972 N57438 W033444 WARNING FLAGS: M-MSA, D-FUEL DUMP REQ., F-DIVERT FUEL REQ. DRIFTDOWN DETAIL DATA DEPRESSURIZED (LRC) DIVERT SUMMARY ... LAT/LONG N57354 W035138 EINN CYYT ETP TIME 03.01 @ 0290KT ETP F.L. 099 ETP FOB 017623 G/C DIST 0945 0872 ETP W/C P024 M001 DRIFTDOWN BURN DATA ... LRC LRC DRIFT F.L. 100 100 ENROUTE TEMP M010 M009 AVG GWT 057544 057487 MSA F.L. 048 024 DRIFTDOWN DUMP FUEL 000000 000000 EMERGENCY DESCENT 000000 000000 CRUISE 009307 009422 FINAL DESCENT 000130 000130 HOLD 000739 000738 TOTAL 010176 010290 ONE ENGINE INOP DIVERT SUMMARY ... LAT/LONG N57438 W033444 EINN CYYT ETP TIME 03.02 @ 0290KT ETP F.L. 236 ETP FOB 017972 G/C DIST 0899 0917 ETP W/C P006 P012 DRIFTDOWN BURN DATA ... 1LE 1LE DRIFT F.L. 250 250 ENROUTE TEMP M041 M033 AVG GWT 058943 058947 MSA F.L. 048 024 DRIFTDOWN DUMP FUEL 000000 000000 DRIFTDOWN DESCENT 000052 000052 CRUISE 007104 007097 FINAL DESCENT 000196 000196 HOLD 000609 000609 TOTAL 007961 007954 Mutt |
CRITICAL FUEL CALCULATION 2ENG 1ENG 2ENG 1ENG CRUISE / FL100 - 17694 03.06 17658 17732 17694 17767 HOLDING/1500FT - 01205 00.15 01206 01092 01205 01091 APU BURN - 00602 00601 00544 00602 00545 ANTI-ICE - 00010 00010 00003 00010 00003 TOTAL FUEL REQD- 19511 03.21 19475 19371 19511 19406 Note the cruise fuel is less for 2ENG than 1ENG, but the 2ENG numbers take a good hit with the holding and EAI. |
Read my Post Mutt...still waiting...LAX to HNL
MTOW, Total fuel, fuel burn at alt, fuel remaining at diversion, new fuel burn at 10000k, fuel remaining upon landing. Come on, are you really going to dance around a simple little performance and planning exercise? Look if you can't do it, you can't do it. Just stay off. |
Just stay off. |
737-800 using LAX and HNL as ETOPS alternates, I'm sure that someone of your experience could suggest better alternates :):)
FUEL TIME ETA NGM NAM FL COMP TEMP WEIGHTS POA PHNL 026845 05:00 0501 2243 2183 380 P010 M50 094.00 OWE ALT PHDH 000829 00:07 0508 HLD 002377 00:30 RES 000000 00:00 REQ 030051 05:37 XTR 000000 00:00 BLST 000000 ETOP 010678 02:15 TOT 040729 07:52 0022 0022 P003 ATW... ./ 026.10 PAYLD 030.05 TO/F 160.83 TO/WT 133.99 LDGWT KLAX/PHNL - EQUAL TIME POINT DATA - ETP1 - - - - - - - - DIVERSION SUMMARY - KLAX PHNL TIME 03.08 @ 0345KT F.L. 0099 FOB 024975 G/C DIST 1116 1105 AVG W/C P012 P008 TEMP @ FL099 P009 P012 BURN SUMMARY FL099 ... 1 ENG. 2 ENG. 1 ENG. 2 ENG. DIVERSION 018457 03.29 018074 018355 018169 018457 HOLD 001141 00.15 001004 001141 001003 001141 MAP 001200 001200 001200 001200 001200 CONSERV. 002164 002123 002154 002131 002164 ICE DRAG 000000 000000 000000 000000 000000 ANTI-ICE 001118 001141 001122 001137 001118 APU 000895 000913 000898 000910 000895 TOTAL 024975 03.44 024455 024870 024550 024975 FOB 024975 QTY DIFF. +000000 DRIFTDOWN SUMMARY DATA CRZ TO BURN FL MSA TO BURN FL MSA FOB LAT LON W LRC*KLAX 019160 100 046 PHNL 019216 100 074 024975 N28444 W139192 1LE*KLAX 015132 220 046 PHNL 015152 220 074 024975 N28444 W139192 WARNING FLAGS: M-MSA, D-FUEL DUMP REQ., F-DIVERT FUEL REQ. DRIFTDOWN DETAIL DATA DEPRESSURIZED (LRC) DIVERT SUMMARY ... LAT/LONG N28444 W139192 KLAX PHNL ETP TIME 03.08 @ 0345KT ETP F.L. 099 ETP FOB 024975 G/C DIST 1116 1105 ETP W/C P012 P008 DRIFTDOWN BURN DATA ... LRC LRC DRIFT F.L. 100 100 ENROUTE TEMP P007 P010 AVG GWT 136259 136231 MSA F.L. 045 073 DRIFTDOWN DUMP FUEL 000000 000000 EMERGENCY DESCENT 000000 000000 CRUISE 017668 017724 FINAL DESCENT 000348 000348 HOLD 001144 001144 TOTAL 019160 019216 ONE ENGINE INOP DIVERT SUMMARY ... LAT/LONG N28444 W139192 KLAX PHNL ETP TIME 03.06 @ 0350KT ETP F.L. 236 ETP FOB 024975 G/C DIST 1116 1105 ETP W/C P010 P007 DRIFTDOWN BURN DATA ... 1LE 1LE DRIFT F.L. 220 220 ENROUTE TEMP M015 M013 AVG GWT 138231 138220 MSA F.L. 045 073 DRIFTDOWN DUMP FUEL 000000 000000 DRIFTDOWN DESCENT 000099 000099 CRUISE 013528 013548 FINAL DESCENT 000472 000472 HOLD 001033 001033 TOTAL 015132 015152 Mutt |
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