Flap retraction/extension during turn
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Again, of it's own accord, the action of raising flaps in a turn is of no consequence. If one raises the flaps when too slow or at too high an angle of attack in level flight, one may stall or descend. If one does the same in a turn, one can expect the same result. The turn, then, is irrelevant. Operation of the airplane with respect to it's own limitations is the issue. Not the turn.
One can certainly bring the flaps up immediately after takeoff and while in a turn departing the runway. I've been doing it for years. Put it in context, however, and you'll find that this isn't standard practice in many types of operations. Bringing the flaps up immediately after takeoff, or bringing them up in a turn is perfectly acceptable if done properly and in context.
Whether one is in a heavy aircraft, a high performance aircraft, or not, one need have no concern about raising flaps in a turn, if one does so sensibly and properly. If one doesn't exercise sense or safety, then whether one is in a turn or not is irrelevant.
One can certainly bring the flaps up immediately after takeoff and while in a turn departing the runway. I've been doing it for years. Put it in context, however, and you'll find that this isn't standard practice in many types of operations. Bringing the flaps up immediately after takeoff, or bringing them up in a turn is perfectly acceptable if done properly and in context.
Whether one is in a heavy aircraft, a high performance aircraft, or not, one need have no concern about raising flaps in a turn, if one does so sensibly and properly. If one doesn't exercise sense or safety, then whether one is in a turn or not is irrelevant.
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Intruder,
I referenced the 737, that's what I fly. Where is irrelevant, we use near standard Boeing procedures.
An immediate turn after takeoff is generally defined as normally a turn at 400'. Abnormally is another question. I presume we are talking about normal ops here.
As I wrote.
What type are you referring to? For the 737 it isn't a gust margin or a stall margin, it is a margin to stick shaker and "adequate" is not 40º+, it is 15º + 15º overshoot. "Full" is defined as 25º + 15º overshoot.
For the 737, "full" manoeuvre capability is only "guaranteed" for takeoff flap and V2+15 or the flap setting and the associated flap manoeuvring speed. That means that between V2+15 (flap 5) and say 190kts (flap 1) it may be assumed to be less than "full" manoeuvring capability. The word "guaranteed" is only used in association with the "flap manoeuvre speed" and not the EFIS speed tape "minimum manoeuvre speed" amber band. The amber band is calculated differently. However, Boeing does say that the amber band and the flap manoeuvring speeds are independent means of assuring "full" manoeuvring capability. Which is a slight contradiction to what is written elsewhere. You decide what is safe. For me I will continue follow the Boeing recommended practice for an immediate turn which is unambiguous.
I don't know what or where you fly
but nobody I know tries to retract flaps in "an immediate turn after take-off." In fact, the general rule in airline operations is NO turn until above 400' AGL!
Further, flap retraction after takeoff is done...DURING ACCELERATION.
If the pilot adheres to the flap retraction schedule, adequate stall and gust margin is available to 40+ deg of bank
There is nothing unsafe about retracting flaps in a turn, as long as the design parameters are met.
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Slightly off topic, but I just have to comment on one thing
An immediate turn after takeoff is generally defined as normally a turn at 400'. Abnormally is another question. I presume we are talking about normal ops here.
Although not airline operations, we normally do 25 degrees of bank as low as 50' in the Kingair B200, out of some airports that have scheduled commercial service. I suspect they (the airline) do the same, since they regularly avoid hitting the hard stuff!
but nobody I know tries to retract flaps in "an immediate turn after take-off." In fact, the general rule in airline operations is NO turn until above 400' AGL!
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May I just make the point that to comply with Schedule A performance (if that is your a/c performance category) the MIN flap retraction height is 400'. Otherwise, I think SNS3 Guppy has said it all.
By the way, can we all just ignore 'bumpyflight' - the posts are not worth commenting on.
By the way, can we all just ignore 'bumpyflight' - the posts are not worth commenting on.
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What type are you referring to? For the 737 it isn't a gust margin or a stall margin, it is a margin to stick shaker and "adequate" is not 40º+, it is 15º + 15º overshoot. "Full" is defined as 25º + 15º overshoot.
. . .
For the 737, "full" manoeuvre capability is only "guaranteed" for takeoff flap and V2+15 or the flap setting and the associated flap manoeuvring speed. That means that between V2+15 (flap 5) and say 190kts (flap 1) it may be assumed to be less than "full" manoeuvring capability. The word "guaranteed" is only used in association with the "flap manoeuvre speed" and not the EFIS speed tape "minimum manoeuvre speed" amber band. The amber band is calculated differently. However, Boeing does say that the amber band and the flap manoeuvring speeds are independent means of assuring "full" manoeuvring capability. Which is a slight contradiction to what is written elsewhere. You decide what is safe. For me I will continue follow the Boeing recommended practice for an immediate turn which is unambiguous.
. . .
For the 737, "full" manoeuvre capability is only "guaranteed" for takeoff flap and V2+15 or the flap setting and the associated flap manoeuvring speed. That means that between V2+15 (flap 5) and say 190kts (flap 1) it may be assumed to be less than "full" manoeuvring capability. The word "guaranteed" is only used in association with the "flap manoeuvre speed" and not the EFIS speed tape "minimum manoeuvre speed" amber band. The amber band is calculated differently. However, Boeing does say that the amber band and the flap manoeuvring speeds are independent means of assuring "full" manoeuvring capability. Which is a slight contradiction to what is written elsewhere. You decide what is safe. For me I will continue follow the Boeing recommended practice for an immediate turn which is unambiguous.
• 1.3g maneuver capability to stick shaker with flaps down
• 1.3g maneuver capability to stick shaker or VREF+80, whichever is less,
with flaps up below 20,200 FT
• 1.3g maneuver capability to low speed buffet (or an alternative approved
maneuver capability as preset by maintenance) above 20,200 FT.
Note: 1.3g maneuver capability occurs at 40 degrees of bank in level flight.
• 1.3g maneuver capability to stick shaker or VREF+80, whichever is less,
with flaps up below 20,200 FT
• 1.3g maneuver capability to low speed buffet (or an alternative approved
maneuver capability as preset by maintenance) above 20,200 FT.
Note: 1.3g maneuver capability occurs at 40 degrees of bank in level flight.
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We're starting to get some crossed wires. Just to clarify - I don't think anyone is advocating cleaning up immediately after takeoff - at least not in a 737.
An immediate turn is okay, if specified. Normally it's 400'. (Or 450' in bumpyflight's world. . .
)
Some SIDs include immediate turns and some have speed restrictions that require us to fly part of the SID at speeds that may require Flaps > 0.
A flap retraction is not recommended on a G/A including a course reversal. (I wonder if there's a certain heading max/min change or radius they have in mind?)
My FCTM is happily buried in a hotel thousands of miles away, so feel free to correct/quote away.
Cheers
An immediate turn is okay, if specified. Normally it's 400'. (Or 450' in bumpyflight's world. . .
)Some SIDs include immediate turns and some have speed restrictions that require us to fly part of the SID at speeds that may require Flaps > 0.
A flap retraction is not recommended on a G/A including a course reversal. (I wonder if there's a certain heading max/min change or radius they have in mind?)
My FCTM is happily buried in a hotel thousands of miles away, so feel free to correct/quote away.
Cheers
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The 737 FCOM i have available (20.05.2010) states
"Any speed between V2 + 15 and V2 + 25 knots results in approximately the same takeoff profile, it provides a safe margin above stall for a 30° bank with a 15° bank overshoot. Crosscheck indicated airspeed for proper initial climb speed."
Which equates to a margin sufficient for up to 45° of bank. However there is a bank angle limitation that states max bank angle after take off is 30°, unless your speed is below V2+15 where it is limited to 15°, but still with a margin of 15° of overshoot.
The same applies to cleaning up, a safe bank angle of 30° with an overshoot of 15° is assured once you're above V2+15.
"Any speed between V2 + 15 and V2 + 25 knots results in approximately the same takeoff profile, it provides a safe margin above stall for a 30° bank with a 15° bank overshoot. Crosscheck indicated airspeed for proper initial climb speed."
Which equates to a margin sufficient for up to 45° of bank. However there is a bank angle limitation that states max bank angle after take off is 30°, unless your speed is below V2+15 where it is limited to 15°, but still with a margin of 15° of overshoot.
The same applies to cleaning up, a safe bank angle of 30° with an overshoot of 15° is assured once you're above V2+15.
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Denti,
I should have stated that I am flying the Classic and that I'm referring to the FCTM of 2008. Ours states 25+15 for full manoeuvring capability.
Anyway, the key point as far as I am concerned is that when you retract flaps on take off using the normal procedure, you will be below the flap manoeuvring speed for the newly selected flap. Whether this is considered unsafe or not is another debate. But that fact is that you are below that speed and as such margins are reduced. This I suspect is the single key issue that must be considered when retracting flaps in a turn after takeoff which is why I associated the immediate turn procedure with this thread.
As I previously stated some of the advice in our FCTM is contradictory and it sounds like this has been cleared up in later versions. Therefore some of this is open to interpretation, but "overshoot" is circumstantially defined as "inadvertent overshoot" (to quote our FCTM). Therefore, unless there is specific guidance that applies the situation in question (such as the written Immediate Turn After Takeoff procedure) and the fact VNAV will command 30º, my view is that 25+15 means that I'll limit my bank angle to 25 (plus minus a degree of human error) and allow 15 for such an inadvertent overshoot. That doesn't mean anything else would be officially or otherwise unsafe, but after gathering all the information and working on a risk/benefit basis that is my choice until our manuals are updated.
The 737 FCOM i have available (20.05.2010) states
Anyway, the key point as far as I am concerned is that when you retract flaps on take off using the normal procedure, you will be below the flap manoeuvring speed for the newly selected flap. Whether this is considered unsafe or not is another debate. But that fact is that you are below that speed and as such margins are reduced. This I suspect is the single key issue that must be considered when retracting flaps in a turn after takeoff which is why I associated the immediate turn procedure with this thread.
As I previously stated some of the advice in our FCTM is contradictory and it sounds like this has been cleared up in later versions. Therefore some of this is open to interpretation, but "overshoot" is circumstantially defined as "inadvertent overshoot" (to quote our FCTM). Therefore, unless there is specific guidance that applies the situation in question (such as the written Immediate Turn After Takeoff procedure) and the fact VNAV will command 30º, my view is that 25+15 means that I'll limit my bank angle to 25 (plus minus a degree of human error) and allow 15 for such an inadvertent overshoot. That doesn't mean anything else would be officially or otherwise unsafe, but after gathering all the information and working on a risk/benefit basis that is my choice until our manuals are updated.
