Flap retraction
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Also, nobody has actually said what their plan is should an engine fail when they are at 1000 feet, take off flap still set, V2 +50 ish. At V2+50, are you still on the required SID gradient?
We go to flaps 0 passing 400ft AND V2 + 20 minimum...
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Hello Dudeness
I think that given the situation lots of us put ourselves in thats a good plan but really the aircraft should already be clean because you've passed the flap up speed (not sure what you fly, soverign maybe). So with the take off flap still set and at a speed appreciably above the flap up speed you are generating extra drag and as soon as the engine fails this becomes a more serious problem. If the flap was already up you would be reducing the speed to the flap up speed or Venr as appropriate and making no further configuration change, you would not be coping with the extra drag, and at all times you would be climbing as well as the aircraft possibly can. With the take off flap still set above the flap up speed you aren't.
Jon, deep down, you've got a sneaky suspicion that I'm onto something and the reason is that you know how Part B's get copied (did I say copied, I meant written)! Worse still, the operator I have just left refuse to change the way they teach us to fly the take off but the wierd thing is that whats in the part B is actually far closer to correct than what we actually do. But nobody reads it and nobody takes any notice of it.
The problem is that nobody thinks it matters but climbing inefficiently, burning extra fuel, making extra noise, and having a rather wierd situation should you lose a powerplant at some point after the flap up speed are all very good reasons to think more carefully about this. There dont seem to be any good reasons at all to keep doing what we are doing!
Just to make the point, Dudeness, whats the reason for the 400 foot call and why do you use it as a flap up trigger? Where has it come from?
(honestly chaps, not being adversarial, just want to work this out)
I think that given the situation lots of us put ourselves in thats a good plan but really the aircraft should already be clean because you've passed the flap up speed (not sure what you fly, soverign maybe). So with the take off flap still set and at a speed appreciably above the flap up speed you are generating extra drag and as soon as the engine fails this becomes a more serious problem. If the flap was already up you would be reducing the speed to the flap up speed or Venr as appropriate and making no further configuration change, you would not be coping with the extra drag, and at all times you would be climbing as well as the aircraft possibly can. With the take off flap still set above the flap up speed you aren't.
Jon, deep down, you've got a sneaky suspicion that I'm onto something and the reason is that you know how Part B's get copied (did I say copied, I meant written)! Worse still, the operator I have just left refuse to change the way they teach us to fly the take off but the wierd thing is that whats in the part B is actually far closer to correct than what we actually do. But nobody reads it and nobody takes any notice of it.
The problem is that nobody thinks it matters but climbing inefficiently, burning extra fuel, making extra noise, and having a rather wierd situation should you lose a powerplant at some point after the flap up speed are all very good reasons to think more carefully about this. There dont seem to be any good reasons at all to keep doing what we are doing!
Just to make the point, Dudeness, whats the reason for the 400 foot call and why do you use it as a flap up trigger? Where has it come from?
(honestly chaps, not being adversarial, just want to work this out)
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Tom, you do recall that on the CJ (for example) there is no 400ft call, don't you?
The SOP is:
I'm not splitting hairs - a call would be yet another layer upon your (alleged) layer of nonsense.
Why not ask eckhard (for it was he what wrote it) where he got the 400ft from? My guess is "The Citation 500 SOPs"
... and so it goes on!
The SOP is:
Above 400ft AAL and V2+10kts PF calls for:
Flap Up
I realise the 400ft prohibition is still there, and I know many people call it, but there is no call in the SOPs.Flap Up
I'm not splitting hairs - a call would be yet another layer upon your (alleged) layer of nonsense.
Why not ask eckhard (for it was he what wrote it) where he got the 400ft from? My guess is "The Citation 500 SOPs"
... and so it goes on!
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We do have a checklist in our airplane... 
It says:
AFTER TAKEOFF/CLIMB
1. LandingGear ......................UP
2. Flaps..................0° (V2 +10 knots and at or above 400 feet AGL)
3. Throttles.................. MCTDetent
4. YawDamper................ AsDesired
5. Autopilot (above 400feet AGL)......... AsDesired
6. Pressurization................... Check
7. SEAT BELTS and PAX SAFETY Buttons . . . As Required
8. Anti-Ice...................AsRequired
9. Altimeters/RECOG Button (at transitionaltitude) ........... Set/OFF
10. APU (prior to climb above FL300). . . . . . OFF (refer to Normal Procedures, APU Shutdown)
And it is a Sovereign, meaning this CL is basically from FSI....
We use + 20 instead of + 10, just because the Sov goes thru these numbers so bloody quick and one usually canīt hold V2+ 10 really...
I do know a guy that would raise flaps almost immediately after takeoff in his CJ3. I donīt like it too much to be honest. Maybe Iīm just slow or stupid, but I like 'to settle in' before changing config. IF I understand 'it' correctly, I can meet all the requirements the way we do it, provided the V2 OEI numbers are achieved. And thats what Iīm interested in most, to be honest...
It says:
AFTER TAKEOFF/CLIMB
1. LandingGear ......................UP
2. Flaps..................0° (V2 +10 knots and at or above 400 feet AGL)
3. Throttles.................. MCTDetent
4. YawDamper................ AsDesired
5. Autopilot (above 400feet AGL)......... AsDesired
6. Pressurization................... Check
7. SEAT BELTS and PAX SAFETY Buttons . . . As Required
8. Anti-Ice...................AsRequired
9. Altimeters/RECOG Button (at transitionaltitude) ........... Set/OFF
10. APU (prior to climb above FL300). . . . . . OFF (refer to Normal Procedures, APU Shutdown)
And it is a Sovereign, meaning this CL is basically from FSI....
We use + 20 instead of + 10, just because the Sov goes thru these numbers so bloody quick and one usually canīt hold V2+ 10 really...
I do know a guy that would raise flaps almost immediately after takeoff in his CJ3. I donīt like it too much to be honest. Maybe Iīm just slow or stupid, but I like 'to settle in' before changing config. IF I understand 'it' correctly, I can meet all the requirements the way we do it, provided the V2 OEI numbers are achieved. And thats what Iīm interested in most, to be honest...
Last edited by His dudeness; 18th Nov 2012 at 15:22.
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flight safety again. Can't say I'm shocked.
Dont forget, I'm not saying you necessarily need to hold V2+10 - thats a noise abatement issue and until we routinely de-rate its totally impractical. What I'm suggesting is that we should select flaps up as soon as we can. If you made the configuration change as soon as you're allowed to I suspect you'd hardly feel it whereas if you make it when you're considerably faster the pitch change is much greater which contributes to the feeling of sinking etc..
I'm going to see if I can find a Cessna manual for the soverign and see what it actually says rather than one thats caught a nasty FSI
Dont forget, I'm not saying you necessarily need to hold V2+10 - thats a noise abatement issue and until we routinely de-rate its totally impractical. What I'm suggesting is that we should select flaps up as soon as we can. If you made the configuration change as soon as you're allowed to I suspect you'd hardly feel it whereas if you make it when you're considerably faster the pitch change is much greater which contributes to the feeling of sinking etc..
I'm going to see if I can find a Cessna manual for the soverign and see what it actually says rather than one thats caught a nasty FSI
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The following comes straight out of the Gulfstream G650 Operating manual.
Normal 2 engine take-off, at positive rate gear up and flaps up. Select FLCH which will command auto throttles to go from V2 to 200kts. No mention of 400'. The 400' call is from the FSI training manual.
Engine failure above V1.
Climb at V2 to 1500' then accelerate to V2+20 flaps up. If engine failure occurs after passing V2 maintain V2+10 as this gives the maximum climb gradient.
In the sim we were using 400' to retract the flaps but this is a Flight Safety call and is nowhere to be found in the Gulfstream documents.
Normal 2 engine take-off, at positive rate gear up and flaps up. Select FLCH which will command auto throttles to go from V2 to 200kts. No mention of 400'. The 400' call is from the FSI training manual.
Engine failure above V1.
Climb at V2 to 1500' then accelerate to V2+20 flaps up. If engine failure occurs after passing V2 maintain V2+10 as this gives the maximum climb gradient.
In the sim we were using 400' to retract the flaps but this is a Flight Safety call and is nowhere to be found in the Gulfstream documents.
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a pattern doth emerge..
I think it may be worth asking Flight Safety.
I shall do it in the morning and report back.
all...very....interesting...
(quite jealous of your G650)
I think it may be worth asking Flight Safety.
I shall do it in the morning and report back.
all...very....interesting...
(quite jealous of your G650)
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I took a photo out of the window of a 320 out of Heathrow recently sitting in the back on the way to paris and I've tried to measure it against the horizon and the deck angle is pretty close to 30 degrees
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Normal 2 engine take-off, at positive rate gear up and flaps up. Select FLCH which will command auto throttles to go from V2 to 200kts
Gulfstream say almost the same thing in the G4, at VFS (minimum) select FLCH.
So if you want to look at things in isolation, there is nothing stopping you are per the manufacturers procedures from retracting the flaps at V2+X and 100 feet. This is exactly the way that you wanted. However if we dont look at things in isolation and the nice "FED" shows up and asks you how you are going to comply with the regulation pertaining to clearing all obstacles in the takeoff flight path, the only way that you can prove it is to refer to the manufacturers AFM (or software), this is based on the certification requirements of FAR 25 with a define profile where 400 feet is stated, so you would have to be able to show that you were in compliance with those procedures.
If FSI teach you the procedures in isolation, then they have just shouldered the legal responsibility for you flying into a mountain.
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Obstacle Clearance
[G-450 AFM 5.6] The obstacle clearance procedure is to climb with landing gear retracted, flaps in takeoff position at a speed of V2 to at least 1500 feet above the takeoff surface. Use of the obstacle clearance data in this section will ensure that obstacles will be cleared by a minimum of 35 feet for dry runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights read from the charts to assure 35 feet minimum clearance. Climb performance is referenced from 2 locations 1) Reference Zero and 2) the Departure End of the Runway (DER). Reference Zero is the point along the runway where the aircraft attains a height of 35 feet for dry runway operations or 15 feet for wet runway operations. Per TERPS (Terminal Instrument Procedures) criteria, SID (Standard Instrument Departure) climb requirements are specified from the DER. Accordingly, when extra runway exists beyond Reference Zero to the DER, different available climb performance is computed for these different reference points. Shown below is a schematic which illustrates the resulting climb performance capabilities from either of these reference points.
Summary: V2+10/400 AND Obstacles cleared....is when you retract flaps..
Zero Zero out of Eagle..where you reduced fuel, changed departure time to the coldest time of day...ect...you are going to leave the flaps down and V2 all the way up.
Code7700
[G-450 AFM 5.6] The obstacle clearance procedure is to climb with landing gear retracted, flaps in takeoff position at a speed of V2 to at least 1500 feet above the takeoff surface. Use of the obstacle clearance data in this section will ensure that obstacles will be cleared by a minimum of 35 feet for dry runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights read from the charts to assure 35 feet minimum clearance. Climb performance is referenced from 2 locations 1) Reference Zero and 2) the Departure End of the Runway (DER). Reference Zero is the point along the runway where the aircraft attains a height of 35 feet for dry runway operations or 15 feet for wet runway operations. Per TERPS (Terminal Instrument Procedures) criteria, SID (Standard Instrument Departure) climb requirements are specified from the DER. Accordingly, when extra runway exists beyond Reference Zero to the DER, different available climb performance is computed for these different reference points. Shown below is a schematic which illustrates the resulting climb performance capabilities from either of these reference points.
Summary: V2+10/400 AND Obstacles cleared....is when you retract flaps..
Zero Zero out of Eagle..where you reduced fuel, changed departure time to the coldest time of day...ect...you are going to leave the flaps down and V2 all the way up.
Code7700
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The net take off path you just described is OEI. What I'm trying to get across is that most operators, on a normal take off, leave the flap in the take off position, go blasting through V2+x, get to 1500 feet at V2+40 or 50 or in many cases more and retract the flap there. Hopefully this is clearly wrong. Many companies SOP's talk about a flap retraction at 1500 feet and those that don't will tend to use a flap retraction at 400 feet. Even the example you just showed me for the 450 doesnt mention 400 feet.
If you look at your marginal day out of Eagle (don't know Eagle, going to read Sion) the argument still holds. If you take off all with all engines operative and somehow manage to make it to your retract speed you WILL have a better gradient if you retract the flaps there EVEN if one engine then fails. This is for a normal take off remember - we're not talking about a noise abatement procedure which calls for a Vx climb to 1500 feet for noise.
The important thing is that the flaps should go up once you've passed the flap retract speed REGARDLESS of the height. I can't find any references in any flight manual anywhere that requires a conditional height for an all engines operating take off. If you are going to take off and remain below the flap up speed then thats great but why do Flight Safety take it upon themselves to teach everyone that there's a 400 foot condition for raising the flap when its clearly rubbish. The level platform (400 foot, 1500 foot, made up 1000 foot for lots of companies) is for acceleration and is called an acceleration altitude. If you don't need it its irrelevant.
Are there any votes for the motion at all? Or is it just me...
If you look at your marginal day out of Eagle (don't know Eagle, going to read Sion) the argument still holds. If you take off all with all engines operative and somehow manage to make it to your retract speed you WILL have a better gradient if you retract the flaps there EVEN if one engine then fails. This is for a normal take off remember - we're not talking about a noise abatement procedure which calls for a Vx climb to 1500 feet for noise.
The important thing is that the flaps should go up once you've passed the flap retract speed REGARDLESS of the height. I can't find any references in any flight manual anywhere that requires a conditional height for an all engines operating take off. If you are going to take off and remain below the flap up speed then thats great but why do Flight Safety take it upon themselves to teach everyone that there's a 400 foot condition for raising the flap when its clearly rubbish. The level platform (400 foot, 1500 foot, made up 1000 foot for lots of companies) is for acceleration and is called an acceleration altitude. If you don't need it its irrelevant.
Are there any votes for the motion at all? Or is it just me...
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tommoutrie
I will be totally amazed if FSI teach anything but the AFM, otherwise they are on very very thin legal ice.
If they express a view otherwise I would get it in writing, with an indemnification. Warren would not be pleased.
Our experience is that if asked about non AFM approved manouevres they may express a personal view but will always return to the manufacturers AFM.
If the manufacturer allows their approved training org to do otherwise they will be codefendants, I dont think so.
You get exited in my organisation for using otherwise, and if a regulator (believe me in my part of the world they sometimes try) or an auditor tries to impose a personal prejudice outside the AFM as a condition of an approval then it's game on.
It usually starts with a polite but firm request from me for a formal personal indemnity from them and their organisation and always ends in a white flag. I have found, at least in my country, the amount of misinformation, lack of background knowledge, prejudice, legend, folkore, and Chief Pilotology astounding. I am fortunate to have been able to hand pick and mentor some outstanding people.
As I am sure you are aware the AFM is the FAA approved reduction of the performance derived from the manufacturers certification process and yes is based on OEI.
SillyPeoples has got it in one, its really all about the departure runway obstacle clearance basket (we use APG to provide RTOW which simplifies the preflight planning matter somewhat) within which we operate and ALL the calculations are based thereon for all combinations of where you may find yourself OEI at any time up to the end of the takeoff phase. The default position for the OEI calculation is V1.
Simply put, if you fly the speeds/AFM to 1500ft, or higher if the particular departure requires, you are gauranteed to have the required obstacled clearance whether one or both are going. Thats what V1 is about.
So, mess with that and you are now a manufacturers test pilot, in an uncertified aircraft and or only guessing where you might lay in the basket up to that point. "Well M'lud up to that point everything was going so well I thought I'd just wing it from there."
The subject under discussion seems to suggest that at some arbitrary time during the take of phase the pilot decides that everything is going just swimmingly so lets clean up and get going.
Sure the modern aircraft can perform all manner of interesting things but not what it can't.
What you can be sure of is that the manufacturer has squeezed the living daylights out of the performance calculations in your manual up to the certification limits available.
Why would they not do otherwise, they are trying to sell you an aircraft with the best possible performance, the FAA on the other hand are intent on keeping them honest.
I might be wrong but if they thought there was a better way it would be in the AFM.
Your theories may well be correct, but this little black duck wont be chancing his arm outside the AFM.
I have sat in court as an expert witness too many times and seen too many unintentional test pilots try to defend what they thought was a good idea at the time.
Anyway I have been wrong before.
I will be totally amazed if FSI teach anything but the AFM, otherwise they are on very very thin legal ice.
If they express a view otherwise I would get it in writing, with an indemnification. Warren would not be pleased.
Our experience is that if asked about non AFM approved manouevres they may express a personal view but will always return to the manufacturers AFM.
If the manufacturer allows their approved training org to do otherwise they will be codefendants, I dont think so.
You get exited in my organisation for using otherwise, and if a regulator (believe me in my part of the world they sometimes try) or an auditor tries to impose a personal prejudice outside the AFM as a condition of an approval then it's game on.
It usually starts with a polite but firm request from me for a formal personal indemnity from them and their organisation and always ends in a white flag. I have found, at least in my country, the amount of misinformation, lack of background knowledge, prejudice, legend, folkore, and Chief Pilotology astounding. I am fortunate to have been able to hand pick and mentor some outstanding people.
As I am sure you are aware the AFM is the FAA approved reduction of the performance derived from the manufacturers certification process and yes is based on OEI.
SillyPeoples has got it in one, its really all about the departure runway obstacle clearance basket (we use APG to provide RTOW which simplifies the preflight planning matter somewhat) within which we operate and ALL the calculations are based thereon for all combinations of where you may find yourself OEI at any time up to the end of the takeoff phase. The default position for the OEI calculation is V1.
Simply put, if you fly the speeds/AFM to 1500ft, or higher if the particular departure requires, you are gauranteed to have the required obstacled clearance whether one or both are going. Thats what V1 is about.
So, mess with that and you are now a manufacturers test pilot, in an uncertified aircraft and or only guessing where you might lay in the basket up to that point. "Well M'lud up to that point everything was going so well I thought I'd just wing it from there."
The subject under discussion seems to suggest that at some arbitrary time during the take of phase the pilot decides that everything is going just swimmingly so lets clean up and get going.
Sure the modern aircraft can perform all manner of interesting things but not what it can't.
What you can be sure of is that the manufacturer has squeezed the living daylights out of the performance calculations in your manual up to the certification limits available.
Why would they not do otherwise, they are trying to sell you an aircraft with the best possible performance, the FAA on the other hand are intent on keeping them honest.
I might be wrong but if they thought there was a better way it would be in the AFM.
Your theories may well be correct, but this little black duck wont be chancing his arm outside the AFM.
I have sat in court as an expert witness too many times and seen too many unintentional test pilots try to defend what they thought was a good idea at the time.
Anyway I have been wrong before.
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Tom
Just noticed in your post.
" If you don't need it it's irrelevant". Too true, but one have to have your eye on the FED.
FSI may be pedantic but the "400ft" clearance remains as a benchmark, is it not he pilots responsibility to satisfy that condition.
Further consider FSI teach on the assumption that this is your Initial, recurrent is a refresher on that so back to "kindly"'perhaps.
How do you teach or recognize different levels of experience/dumbosity. Some of their pupils are smart some are dumb, so they have to default to dumb.
A corporate dept near me had their so called legend in his own lunchbox sent home, despite their considerable teaching skills, as he was unable to handle the upgrade. Not surprised mind you, but humbling for him nonetheless, to his credit he eventually got there but not without an enforceable undertaking to have an approved pilot in the cockpit for a period.
Interesting stuff as the performance of the aircraft we now have improves beyond belief.
I never thought I would ever see M.83 in the climb schedule. Clearly the installed thrust required to get over M.9 in the cruise is way more than necessary to get away from mother earth in a sprightly manner. I hasten to add I am not rated in the type but have spent a bit of time in the sim and aircraft.
Just noticed in your post.
" If you don't need it it's irrelevant". Too true, but one have to have your eye on the FED.
FSI may be pedantic but the "400ft" clearance remains as a benchmark, is it not he pilots responsibility to satisfy that condition.
Further consider FSI teach on the assumption that this is your Initial, recurrent is a refresher on that so back to "kindly"'perhaps.
How do you teach or recognize different levels of experience/dumbosity. Some of their pupils are smart some are dumb, so they have to default to dumb.
A corporate dept near me had their so called legend in his own lunchbox sent home, despite their considerable teaching skills, as he was unable to handle the upgrade. Not surprised mind you, but humbling for him nonetheless, to his credit he eventually got there but not without an enforceable undertaking to have an approved pilot in the cockpit for a period.
Interesting stuff as the performance of the aircraft we now have improves beyond belief.
I never thought I would ever see M.83 in the climb schedule. Clearly the installed thrust required to get over M.9 in the cruise is way more than necessary to get away from mother earth in a sprightly manner. I hasten to add I am not rated in the type but have spent a bit of time in the sim and aircraft.
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Tom
Just a thought, is the 400 ft not just giving time for the gear to be completely up before you start the flap up selection!! On the 550 the flaps take a very long time from 10 -0 my guess is you are easily through 1500 feet on a normal SID before the flaps are fully retracted. So if you started retracting them at 1500 ft on a normal climb, you will probably be at 250 kts before they are retracted fully depending on the MSSA that you have set in the box to maintain 200kts.
You really don't have time to do it before 400 ft because of speed and then selecting the gear up.
Just a thought, is the 400 ft not just giving time for the gear to be completely up before you start the flap up selection!! On the 550 the flaps take a very long time from 10 -0 my guess is you are easily through 1500 feet on a normal SID before the flaps are fully retracted. So if you started retracting them at 1500 ft on a normal climb, you will probably be at 250 kts before they are retracted fully depending on the MSSA that you have set in the box to maintain 200kts.
You really don't have time to do it before 400 ft because of speed and then selecting the gear up.
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I will be totally amazed if FSI teach anything but the AFM, otherwise they are on very very thin legal ice.
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Which rule? Where is this rule about not taking flaps before 400 feet?
Let me stick my neck out further. Some of the responses are concerned that retracting the flaps at the manufacturers recommended speed may be flirting somehow with the net take off flight path and therefore putting you in a sticky situation should you actually lose an engine.
The opposite is true. If you DONT take the flap up and continue to accelerate you are potentially putting yourself in the area where you don't know what gradient you can achieve.
Here's why. Lets use V2+10 as the generic flap up speed because I can't be bothered to type all the caveats.
V1, rotate, take off, positive rate, select gear up, accelerate to V2. So far it makes no difference whether you lose an engine or not - we do the same thing. However, if you have lost one you remain at V2 (or slightly over because if you go below V2 the drag markedly increases because thats the side of the LD curve you're on which is why we climb at V2 to V2+10). We don't climb on one engine at V2+30 or 40 because.....
THE DRAG IS HIGH BECAUSE OF THE FLAP
Does anyone disagree with that bit?
Ok so lets say both engines are still running and we accelerate from V2 to V2 +10. Now you are at the point where you can take the flap up. The reason you can do this is the manufacturer says this is the time where changing characteristic of lift and drag is least - look at the curves. The LD curves for flapless and flapped are closest at this point. If you keep accelerating with flap then the drag just keeps increasing - you don't get a busting lot more lift out of the wing. If you take the flap where the manufacturer suggests, the pitch change is smaller and as you don't have the increased drag you accelerate/climb a bit better. You use less fuel, you get away from the ground better. And if you do lose an engine you are in a clean aeroplane thats climbing better and easier to fly.
There is no downside.
The idea that we take off and have to make sure we are above 400 feet before retracting the flaps is a myth. The idea that we may somehow move the wrong lever and that would be a disaster is just rubbish otherwise we would have decision altitudes on approach which reflected that.
Why make a call for flaps based on anything other than speed - speed is all that flaps care about! Why complicate the call for the PM and require the call to be conditional on two parameters?
Whats happened over the years is that operators have become confused by teaching from FSI and others, missives regarding noise abatement requirements, and attempts to standardise what happens on a normal take off compared to what happens if an engine fails.
The answer to the last problem is they have always been the same - its willie waving nonsense thats make it complicated. You take off, if you get to V2 you climb, if you get to V2+10 you raise the flaps. If you have lost a powerplant or, indeed, if you cant accelerate and climb adequately for any reason, you can use a pre-arranged acceleration platform to do that and raise the flaps there.
so now I've gone further and suggested that what most people do doesn't actually comply with the rules.. now everybody will hate me.. whats the number of that truck driving school, truckmaster I think it is...
Let me stick my neck out further. Some of the responses are concerned that retracting the flaps at the manufacturers recommended speed may be flirting somehow with the net take off flight path and therefore putting you in a sticky situation should you actually lose an engine.
The opposite is true. If you DONT take the flap up and continue to accelerate you are potentially putting yourself in the area where you don't know what gradient you can achieve.
Here's why. Lets use V2+10 as the generic flap up speed because I can't be bothered to type all the caveats.
V1, rotate, take off, positive rate, select gear up, accelerate to V2. So far it makes no difference whether you lose an engine or not - we do the same thing. However, if you have lost one you remain at V2 (or slightly over because if you go below V2 the drag markedly increases because thats the side of the LD curve you're on which is why we climb at V2 to V2+10). We don't climb on one engine at V2+30 or 40 because.....
THE DRAG IS HIGH BECAUSE OF THE FLAP
Does anyone disagree with that bit?
Ok so lets say both engines are still running and we accelerate from V2 to V2 +10. Now you are at the point where you can take the flap up. The reason you can do this is the manufacturer says this is the time where changing characteristic of lift and drag is least - look at the curves. The LD curves for flapless and flapped are closest at this point. If you keep accelerating with flap then the drag just keeps increasing - you don't get a busting lot more lift out of the wing. If you take the flap where the manufacturer suggests, the pitch change is smaller and as you don't have the increased drag you accelerate/climb a bit better. You use less fuel, you get away from the ground better. And if you do lose an engine you are in a clean aeroplane thats climbing better and easier to fly.
There is no downside.
The idea that we take off and have to make sure we are above 400 feet before retracting the flaps is a myth. The idea that we may somehow move the wrong lever and that would be a disaster is just rubbish otherwise we would have decision altitudes on approach which reflected that.
Why make a call for flaps based on anything other than speed - speed is all that flaps care about! Why complicate the call for the PM and require the call to be conditional on two parameters?
Whats happened over the years is that operators have become confused by teaching from FSI and others, missives regarding noise abatement requirements, and attempts to standardise what happens on a normal take off compared to what happens if an engine fails.
The answer to the last problem is they have always been the same - its willie waving nonsense thats make it complicated. You take off, if you get to V2 you climb, if you get to V2+10 you raise the flaps. If you have lost a powerplant or, indeed, if you cant accelerate and climb adequately for any reason, you can use a pre-arranged acceleration platform to do that and raise the flaps there.
so now I've gone further and suggested that what most people do doesn't actually comply with the rules.. now everybody will hate me.. whats the number of that truck driving school, truckmaster I think it is...
Join Date: Mar 2004
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Okay, I hate you now. Satiesfied?
Right, donīt mention it....
Well, it might a myth, BUT in my airplane its in the official checklist/AFM.
And even if we have a tad more drag between 0 and 400agl, Iīm comfortable with the idea of having some time to observe, check and act before doing anything even on a non-event departure...
Right, donīt mention it....
The idea that we take off and have to make sure we are above 400 feet before retracting the flaps is a myth. The idea that we may somehow move the wrong lever and that would be a disaster is just rubbish otherwise we would have decision altitudes on approach which reflected that.
And even if we have a tad more drag between 0 and 400agl, Iīm comfortable with the idea of having some time to observe, check and act before doing anything even on a non-event departure...
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Join Date: Jan 2002
Location: london, UK
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well that fair enough - its your plane. What do you do with the flaps on a go-around? Do you fairly smartly go from flap land to whatever the take off setting is or sit about for a bit, just in case? The difference between taking the flap passing V2+10 and waiting for 400 feet is probably not much in terms of drag but I think its important for pilots to make flap settings for the right reason and that reason is the speed, not the height.
and... where the hell does it come from!! If its so ingrained that Flight Safety are now writing checklists in conjunction with Cessna the thick will plotten!!
..just saying..
and... where the hell does it come from!! If its so ingrained that Flight Safety are now writing checklists in conjunction with Cessna the thick will plotten!!
..just saying..