737-800 Max speed / min distance emergency on finals?
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737-800 Max speed / min distance emergency on finals?
Really need to do this exercise in the sim....but until I do would appreciate some input.
Historically a civillian jet aircraft with an uncontrolable fire in the engines/hold/cabin has an average time between discovery and aircraft break up between 10 to 12 mins (40 years average) depending on the source of stats.
On the basis that all extinguishers have failed and the aircraft needs to get on the ground ASAP what is the minimum distance an aircraft at say 65 tonnes could around maintain 330 knots on finals. Also interested on peoples views on extending the gear at this speed and how far above the limit speed it would be before you run the risk of making the flaps unusable.
Clearly this is not an exact science...I do have my own views but am interested in a constructive debate. Thanks in advance.
Historically a civillian jet aircraft with an uncontrolable fire in the engines/hold/cabin has an average time between discovery and aircraft break up between 10 to 12 mins (40 years average) depending on the source of stats.
On the basis that all extinguishers have failed and the aircraft needs to get on the ground ASAP what is the minimum distance an aircraft at say 65 tonnes could around maintain 330 knots on finals. Also interested on peoples views on extending the gear at this speed and how far above the limit speed it would be before you run the risk of making the flaps unusable.
Clearly this is not an exact science...I do have my own views but am interested in a constructive debate. Thanks in advance.
alosaurus,
I would not take it to the very edge, rather I'd allow a bit of a fudge factor. After all, slowing down a couple of miles early is going to be a whole lot safer than buggering it up and either running off the end or having a missed approach.
In the real deal this would be one of the absolutely most stressful situations ever in your whole life so don't count on being absolutely 100% on the ball. This would not be a time to learn new techniques. Be just a bit conservative and get it on the ground!
About extending the gear well above Vlo - I'd do it and never mind the damage to the fairings etc, but I would do it prior to any flap extension to avoid bits hitting the flaps.
I would not take it to the very edge, rather I'd allow a bit of a fudge factor. After all, slowing down a couple of miles early is going to be a whole lot safer than buggering it up and either running off the end or having a missed approach.
In the real deal this would be one of the absolutely most stressful situations ever in your whole life so don't count on being absolutely 100% on the ball. This would not be a time to learn new techniques. Be just a bit conservative and get it on the ground!
About extending the gear well above Vlo - I'd do it and never mind the damage to the fairings etc, but I would do it prior to any flap extension to avoid bits hitting the flaps.
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Sorry, Line shoot coming up. I had the misfortune to have an aircraft decide to combust right after T/O at a Canadian field, did a dumbell back to a crossing runway {Downwind} total time in the air just over one minute fourty, already there was spar damage. Air Canada had a Viscount burn after T/O at a Quebec field, time in the air was I belive about four minutes, all the engine controlls on the affected side burned through and the spar melted just after they got out, one fatal, a woman pushed by a blocking FA and jumped out the wrong side.In Austrailia similar stories with two aircraft, one planted it on the ground right away, one didnt, gues which crew/pax made it. If its burning and its not responding to the fire bottles, put the thing in a field, better to be critsized after wrecking an aircraft than need DNA to identify you. God knows what one does in the middle of the Oggin! The little aircraft I fly right now has a long range tank in each nacelle, right behind the turbo, acording to the owners club you have ten minutes max to get it down if things go bang around the turbo. To sum up, if you can get sim time to play "what if", then do it.
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Try 330 IAS at 18 nm. LVL flight 3000 AGL. Bug to up speed (210 for 65T) Flaps out on schedule speed plus 15 to 20 kts and you will be established no later than 1000 AGL with F30 Vref 152.
Should work.
Should work.
All spar-mounted engines, it has to be said, clunck. It's why jets now have pod-mounted engines. 
Flying freight in a westwind I used to occasionally fly MMO (360 knots) to a 10 mile final, with a 90º intercept on the ILS. First flap at 240 knots, second at 220, gear at 180 (all the limit speeds) - and cross the fence (still in idle) at Vref. Westwind has less momentum (and much better speed brakes) than a 737 of course ...
Flying freight in a westwind I used to occasionally fly MMO (360 knots) to a 10 mile final, with a 90º intercept on the ILS. First flap at 240 knots, second at 220, gear at 180 (all the limit speeds) - and cross the fence (still in idle) at Vref. Westwind has less momentum (and much better speed brakes) than a 737 of course ...
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Quite new on the 73-700 myself and only a lowly FO but I do brief that if visual in this scenario (uncontained fire/any fire) it will be a visual to land, a circuit or a 180 wind and traffic dependant.
Checklists can be run time permitting but all I/we need is speeds set for approach, gear and flaps down. Anything else is nice to have but not necessary.
IMC, bets are off but a tight vectored ILS to a short say 6 mile final, hoping the emergency turn isn't to convoluted!!
Just saw your post Checkers, your thoughts on a cabin fire or unextinguished hold fire? only the thought of any fire airbourne scares me to death.
Checklists can be run time permitting but all I/we need is speeds set for approach, gear and flaps down. Anything else is nice to have but not necessary.
IMC, bets are off but a tight vectored ILS to a short say 6 mile final, hoping the emergency turn isn't to convoluted!!
Just saw your post Checkers, your thoughts on a cabin fire or unextinguished hold fire? only the thought of any fire airbourne scares me to death.
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Checkboard, Certainly pod mounted engines help, but there are cases of chunks of engines punching holes in the wing tanks with very nasty results. The bottom line is there is no such thing as a " "Minor" fire when airbourne, get the sucker on the ground ASAP, most electrical and smoke of unknown source checklists are pretty long, { Swissair into Peggys Cove} trying it out in the sim is well worth it
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Latest airliner rolling average I can find (from discovery to becoming non survivable) is 17 mins. SKYbrary - Fire in the Air
777 when does the gear come out in your scenario (and would you lower it at placard speed or 15 to 20 knots above)?
777 when does the gear come out in your scenario (and would you lower it at placard speed or 15 to 20 knots above)?
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335 KIAS, 13 nm. It won't be pretty but it can be done.
3000' AGL? Huh? "It's hard to go down and slow down".
How about 1500' AGL, until the 'drag required' point. At that point start climbing (ramping uphill) to slow faster. Full speedbrakes, gear at limit speed, flaps at limit speeds, idle descent for glide slope. You'll be at idle through 500'..
Like I said, it won't be pretty but it can be done. I'd plan max speed to 15 nm and 2000' AGL max. Not as ugly, still a max performance event.
Now lets say it happened at max cruise altitude. Oh, things just got a lot tougher. Max certified altitude with emergency descent to a max performance arrival (see first paragraphs) to stopping on a runway is approx. 9 minutes and 60 nm. So the 10-12 minute window does not have time to spare.
No, this is not something to practice in the airplane.
3000' AGL? Huh? "It's hard to go down and slow down".
How about 1500' AGL, until the 'drag required' point. At that point start climbing (ramping uphill) to slow faster. Full speedbrakes, gear at limit speed, flaps at limit speeds, idle descent for glide slope. You'll be at idle through 500'..
Like I said, it won't be pretty but it can be done. I'd plan max speed to 15 nm and 2000' AGL max. Not as ugly, still a max performance event.
Now lets say it happened at max cruise altitude. Oh, things just got a lot tougher. Max certified altitude with emergency descent to a max performance arrival (see first paragraphs) to stopping on a runway is approx. 9 minutes and 60 nm. So the 10-12 minute window does not have time to spare.
No, this is not something to practice in the airplane.
Last edited by misd-agin; 11th Aug 2010 at 02:31. Reason: grammar/type
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The most important thing is to keep cool. When you do things out of the ordinary, it is extremely easy to forget something vital, ie forgetting speedbrakes out or not armed etc. So if you are 330 at 18 nm out lvl at 3000 AGL for a straight in 3 degree approach, you will reach 10 nm with a speed between 250 and 240, perfect time for F1. Flap 1 green light, F5. You will then be at 7 nm descending with speed around 200, low drag to 5 nm gear down wait for 190, F15 and so on. Rather 30 seconds extra time than risking an overrun or similar undesirable event.
Alternatively if you are very high, you can get everything out F40 fully configured in ALT hold, drop the nose with speed Vfly and you will be able to loose 1000 ft for every nm. Plan at least 1000 ft buffer to get established, so 9000 AGL at 10 nm fully configured will work provided you keep the speed between Vref and Vfly idle thrust (fly manually as the AP most probably will capture a false glide beam at 6 degrees).
Alternatively if you are very high, you can get everything out F40 fully configured in ALT hold, drop the nose with speed Vfly and you will be able to loose 1000 ft for every nm. Plan at least 1000 ft buffer to get established, so 9000 AGL at 10 nm fully configured will work provided you keep the speed between Vref and Vfly idle thrust (fly manually as the AP most probably will capture a false glide beam at 6 degrees).
