do we really need to retract flaps in case of an engine failure after take-off?
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You have to love PPruNers .. dogmatic answers from their own narrow viewpoint.
In a 3 or 4-engined aircraft above specific TOW you do need to retract the flaps ASAP, so that if another engine fails you are flying fast enough to survive on the remaining one/two.
In a twin this is not a consideration. As NoD pointed out, the A320 has a procedure entitled "IMMEDIATE VMC LDG FOLLOWING ENG FAILURE ON T/O" which involves remaining at FLAP 1 for a visual circuit.
I have no knowledge of other modern twins, but many years ago, on suitable days, a BAC-111 skipper used to finish his EFTO briefing with "but in reality I will level off at a thousand feet, turn downwind and land...."
So my answer is... it depends.
In a 3 or 4-engined aircraft above specific TOW you do need to retract the flaps ASAP, so that if another engine fails you are flying fast enough to survive on the remaining one/two.
In a twin this is not a consideration. As NoD pointed out, the A320 has a procedure entitled "IMMEDIATE VMC LDG FOLLOWING ENG FAILURE ON T/O" which involves remaining at FLAP 1 for a visual circuit.
I have no knowledge of other modern twins, but many years ago, on suitable days, a BAC-111 skipper used to finish his EFTO briefing with "but in reality I will level off at a thousand feet, turn downwind and land...."
So my answer is... it depends.
As BOAC has pointed out - this question was specific for the 737.
There is very little (I will not say None - although it was what was taught on my type rating course) drag at flap 1 or flap 5 - as evidenced by the fact that the aircraft will not descend appreciably better with these settings - you need at least flap 10 to get any noticeable drag.
So in the circumstances asked in the original question there is no reason apart from SOPs why you should bring the flap up, although you could perhaps consider that on a flap 15 take off you might go from flap 15 to flap 5 then stay there until you get to "gear down flap 15 landing checks" on the final approach.
All that assume no performance issues (apart from the choice of take-off flap setting) as given in the original question.
There is very little (I will not say None - although it was what was taught on my type rating course) drag at flap 1 or flap 5 - as evidenced by the fact that the aircraft will not descend appreciably better with these settings - you need at least flap 10 to get any noticeable drag.
So in the circumstances asked in the original question there is no reason apart from SOPs why you should bring the flap up, although you could perhaps consider that on a flap 15 take off you might go from flap 15 to flap 5 then stay there until you get to "gear down flap 15 landing checks" on the final approach.
All that assume no performance issues (apart from the choice of take-off flap setting) as given in the original question.
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TyroPicard:
You got that one right. Why let those pesky certfication/operational considerations get in the way of pilot instinct?
In all my years flying a four-engine aircraft, this is the first time I've heard that we retract flaps on the OEI profile because we may lose another one. No doubt that is a possibility but far more remote than suffering adverse consequences from improperly flying the specified profile.
You have to love PPruNers .. dogmatic answers from their own narrow viewpoint.
In all my years flying a four-engine aircraft, this is the first time I've heard that we retract flaps on the OEI profile because we may lose another one. No doubt that is a possibility but far more remote than suffering adverse consequences from improperly flying the specified profile.
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VMC? i really don't think it's necessary for my decision.
and this is what i mean "increasing work load"!
From the logical point of view, if wx and mother Earth are not an issue, the easiest way to turn back is a visual pattern and then if one has sufficient speed and is light on load, one could leave the flaps at a lower setting than T/O. But then comes the issue that maybe if, for any reason, you haven't completed all checks and procedures and you already have to start to configure for landing...talk about increasing workload!
I'd take my time, the thing should fly on one engine anyway (unless it is fuel contamination/starvation
) so why rush things? Do things accordingly at due time and Bob's your uncle
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What's the rush with a simple engine failure? It is not a situation where you have to land back immediately, in fact you might have to use a take off alternate due to performance issues, low vis doesn't matter anymore with OEI CAT IIIa certification in the 737. On the other hand flying around with flaps 25 (which is a normal take off flaps setting) just because i do not like to bring the flaps up from take off setting seems rather stupid as well.
However in any situation requiring immediate return simply use the Immediate Landing Checklist on Back Cover 1 in the QRH which does not require to raise the flaps.
However in any situation requiring immediate return simply use the Immediate Landing Checklist on Back Cover 1 in the QRH which does not require to raise the flaps.
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I'd suggest the risk of fouling things up because you deviate from SOP/NNOP/QRH procedures in the circumstances suggested, exceeds the benefit of any heroic attempts at adhoc procedure design "on the fly".
If some pilots were as attentive to detail in their flying as they are at their keyboard, I'm sure we'd have a few more smokin' holes in the desert.
If some pilots were as attentive to detail in their flying as they are at their keyboard, I'm sure we'd have a few more smokin' holes in the desert.
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again, thank everyone for your great ideas!
no matter which method we will take, the top priority is satisfy the minimum certificated path profile, this is no doubt.
i have to say i didn't calculate it. but from a pilot's instinct, B737 will satisfy that at Maldives----for this case,we have a minimum 1.2%. Since this number is set up before maybe 20years ago(i guess) and applied to every model of aircraft in the modern age, we can believe a B737 can achieve that in most circumstances.Anyway, if we want to put it as a reasonable supplement to company's SOP, we have to provide convincing performance analysis. i will work on it.
and yes, for this situation, most company's policy define it an urgency and only a "pan-pan" call is needed. we don't need to rush,but we still want to degrade the crews' work load, right?
another thing, all my assumptions are based on flap 5 for take-off. we were just starting use CALTOW method in our flights 1 year ago, but normally most pilots in our company like to use flap 5.
Have you checked that you can always meet the requirement of 25.111(c)(3)(i) with one engine inoperative, the remaining engine at maximum continuous thrust, and flaps in the takeoff setting?
i have to say i didn't calculate it. but from a pilot's instinct, B737 will satisfy that at Maldives----for this case,we have a minimum 1.2%. Since this number is set up before maybe 20years ago(i guess) and applied to every model of aircraft in the modern age, we can believe a B737 can achieve that in most circumstances.Anyway, if we want to put it as a reasonable supplement to company's SOP, we have to provide convincing performance analysis. i will work on it.
and yes, for this situation, most company's policy define it an urgency and only a "pan-pan" call is needed. we don't need to rush,but we still want to degrade the crews' work load, right?
another thing, all my assumptions are based on flap 5 for take-off. we were just starting use CALTOW method in our flights 1 year ago, but normally most pilots in our company like to use flap 5.
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Just a thought:
Maybe the OP knows what is SOP or NNOP or what have you. However, maybe he wants to know theoretically if this makes sense or why Boeing doesn't consider this, etc.
To say "because the book says so" isn't really much of an answer.
Maybe not all runways require us to go to Flaps 0.
What if we could fly? If God wanted us to fly, we'd have wings.
Maybe the OP knows what is SOP or NNOP or what have you. However, maybe he wants to know theoretically if this makes sense or why Boeing doesn't consider this, etc.
To say "because the book says so" isn't really much of an answer.
Maybe not all runways require us to go to Flaps 0.
What if we could fly? If God wanted us to fly, we'd have wings.
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Minor point of style ..
from a pilot's instinct, B737 will satisfy that at Maldives----for this case,we have a minimum 1.2%
Generally, the minimum surveyed slope published is 1.2%. However, the minimum second segment WAT gradient required (ie often limiting the TOW for less terrain challenged runways) is 1.6% net for twins.
from a pilot's instinct, B737 will satisfy that at Maldives----for this case,we have a minimum 1.2%
Generally, the minimum surveyed slope published is 1.2%. However, the minimum second segment WAT gradient required (ie often limiting the TOW for less terrain challenged runways) is 1.6% net for twins.
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and yes, for this situation, most company's policy define it an urgency and only a "pan-pan" call is needed
(for a twin engine, that is)
I was in the B737-800 sim the other day.
Low vis take-off at MTOW (79 t) and 15 kt quartering tailwind. ( 10 kt TW, 10 kt XW). Engine failed shortly after V1. (They're mean aren't they!)
No significant terrain ahead so engine out procedure was simply to track straight ahead with a standard acceleration altitude of 800 ft AGL.
During the flap retraction, I held the vertical speed at zero so there was no way we could have accelerated any quicker than we did.
Guess what. We didn't reach Flap Up manoeuvring speed until we were almost 30 nm from the aerodrome! It seemed to take for ever!
Now in this case with the visibility being so low, it probably did make sense to clean up as there was no chance of returning for a landing. A diversion to "return airport" was the only option. But imagine if the weather was fine and there was an engine fire, or severe engine damage. You're going to want to return for a landing as soon as possible. Over weight landing? So be it.
How can flying 30 nm away be safer than simply accelerating to flap 5 manoeuvering speed, keeping the aircraft close to the airport, and getting the aircraft back on the ground that much more quickly?
Don't forget that the extra time spent accelerating to flap up speed, can't be used to get much else done in the flight deck. Both pilots should be making sure the aircraft is flown correctly.
So for me, it's a valid question worthy of discussion.
Low vis take-off at MTOW (79 t) and 15 kt quartering tailwind. ( 10 kt TW, 10 kt XW). Engine failed shortly after V1. (They're mean aren't they!)
No significant terrain ahead so engine out procedure was simply to track straight ahead with a standard acceleration altitude of 800 ft AGL.
During the flap retraction, I held the vertical speed at zero so there was no way we could have accelerated any quicker than we did.
Guess what. We didn't reach Flap Up manoeuvring speed until we were almost 30 nm from the aerodrome! It seemed to take for ever!
Now in this case with the visibility being so low, it probably did make sense to clean up as there was no chance of returning for a landing. A diversion to "return airport" was the only option. But imagine if the weather was fine and there was an engine fire, or severe engine damage. You're going to want to return for a landing as soon as possible. Over weight landing? So be it.
How can flying 30 nm away be safer than simply accelerating to flap 5 manoeuvering speed, keeping the aircraft close to the airport, and getting the aircraft back on the ground that much more quickly?
Don't forget that the extra time spent accelerating to flap up speed, can't be used to get much else done in the flight deck. Both pilots should be making sure the aircraft is flown correctly.
So for me, it's a valid question worthy of discussion.
Last edited by Blip; 4th Jan 2011 at 05:49.
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Congratulations "eagle 737"! What an interesting hornets nest you've set off. First and formost you should be commended for THINKING as opposed to being an FOM/POH/AFM junkie. Todays airline training syllabus is more or less geared to the lowest common D. Japan Airlines is a classic example of what you get when you don't allow thinking outside the box. In Anchorage AK we used to watch the JAL 747's make numerous visual approaches to the no ILS runway - you could hear the power go up then back to idle then back up then back down followed by a miss. They were simply out of their element. Remember YOU are the Captain! An engine failure IS an EMERGENCY--Declare it! Handle it as you see fit--You have the authority to deviate from any Regulation and proceedure to deal with it.
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THINKING as opposed to being an FOM/POH/AFM junkie
Such documents definitely should be read with commonsense and a modicum of intelligence.
Indeed, I can recall the then Head of Certification in the local Regulator observing that one didn't necessarily need to observe the documents .. with the caveat that one might then be called upon by the Regulator, insurer, or the legal system to demonstrate compliance with the Certification etc. requirements for the "non-compliance(s)".
That is to say, "thinking" is eminently admirable and to be commended .. but make sure that it is backed up by a LOT of knowledge if you intend to go it alone. Even where the commander exercises command prerogative ... he/she may have to justify the decision to go outside the rules with considerable risk of penalty if the story is not up to speed ...
For instance, looking at the POH side of things, I routinely conducted takeoffs with zero flap in light twins when the POH/AFM didn't contain data for that configuration. However, I had done my own reasonable and conservative calculations backed up by some simple flight tests to confirm the sums .. the Regulator's folks (both Certification and Flying Operations) never once queried my approach to the matter ..
One of the benefits of complying with the published requirements is that you are then placed rather strongly to argue the point after the fact ..
Such documents definitely should be read with commonsense and a modicum of intelligence.
Indeed, I can recall the then Head of Certification in the local Regulator observing that one didn't necessarily need to observe the documents .. with the caveat that one might then be called upon by the Regulator, insurer, or the legal system to demonstrate compliance with the Certification etc. requirements for the "non-compliance(s)".
That is to say, "thinking" is eminently admirable and to be commended .. but make sure that it is backed up by a LOT of knowledge if you intend to go it alone. Even where the commander exercises command prerogative ... he/she may have to justify the decision to go outside the rules with considerable risk of penalty if the story is not up to speed ...
For instance, looking at the POH side of things, I routinely conducted takeoffs with zero flap in light twins when the POH/AFM didn't contain data for that configuration. However, I had done my own reasonable and conservative calculations backed up by some simple flight tests to confirm the sums .. the Regulator's folks (both Certification and Flying Operations) never once queried my approach to the matter ..
One of the benefits of complying with the published requirements is that you are then placed rather strongly to argue the point after the fact ..
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Guess what. We didn't reach Flap Up manoeuvring speed until we were almost 30 nm from the aerodrome! It seemed to take for ever!
for sim,time is money. for real flight, sometimes time is life and time is pressure.
after each recurrent training, i will have sth. to write down. can i handle every emergency just perfect in real life? i don't know, i will try but i have to say i will still feel some pressure even after 10 sec deep breath. i hope i'm not the only one here to feel like this
our SOP defines an engine failure after take-off a "URGENCY" and an engine fire a "DISTRESS", but meanwhile SOP always give the captain an authority to judge and declare the situation by himself. for my personal view, it's not such a big difference between them.
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Oh dear, oh dear, oh dear!
I cringe when I read this sort of scary stuff:
Boeing is not the GOD, and its procedure is not the Bible,at least we may give it some good supplementary idea--and that's why we have so many company's policy.
and further, equally scary:
but normally most pilots in our company like to use flap 5.
Boeing (Airbus) SOPs good; invariably, Chief Pilot's, Ops Director, Chief Trng Cpt's versions, BAD!!!!!! VERY BAD!!!! and AWFUL!!!!!
If it's not broken, don't fix it springs to mind.
I cringe when I read this sort of scary stuff:
Boeing is not the GOD, and its procedure is not the Bible,at least we may give it some good supplementary idea--and that's why we have so many company's policy.
and further, equally scary:
but normally most pilots in our company like to use flap 5.
Boeing (Airbus) SOPs good; invariably, Chief Pilot's, Ops Director, Chief Trng Cpt's versions, BAD!!!!!! VERY BAD!!!! and AWFUL!!!!!
If it's not broken, don't fix it springs to mind.