Selecting flaps during turns
Here's something albeit in a slightly different direction. Not me, but it did happen. Your destination is Wellington NZ, light rain, nil wind. Aircraft 767. Final approach. Upon selecting landing flap, flap asymmetry warning, flaps frozen. Cannot be moved at all. Dirty go around. Checklist action gives approach speed Vref 20 + 20, about 165 knots. Runway length required is well beyond the length of the runway. Even with alternate fuel, diversion not possible as alternate fuel never assumes that the aircraft will be dirty (and limited to FL200). What could be done?
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What could be done?
Advise emergency services of potential brake fire.
Burn or dump fuel down to minimum reserve plus enough for a second go just in case first go is untidy.
Complete appropriate checklist and fly appropriate speed for weight. Going below Vref for config invites a tail strike, so don’t do that!
Fly stable approach to touch down, do not accept float, a firm landing on the spot is what you want.
Land and throw everything at stopping - spoilers, brakes, reverse.
Exit runway if possible, but do not taxi to the ramp.
Complete hot brakes checklist.
Think aloud throughout - for the benefit of the tape.
Complete paperwork as to why you did not have the full performance ‘buffers’.
Tech Log entry to change brakes, wheels, tyres or whatever MOM calls for. Maintenance will want touch down groundspeed and rate of descent, so it is helpful if the FO can make a mental note of these. If not, give them PIDOOMA. or they can probably access it via QAR.
Been there and done it twice; both occasions the runway was limiting. One tyre fuse plug blew on one occasion, but only after we stopped.
Burn or dump fuel down to minimum reserve plus enough for a second go just in case first go is untidy.
Complete appropriate checklist and fly appropriate speed for weight. Going below Vref for config invites a tail strike, so don’t do that!
Fly stable approach to touch down, do not accept float, a firm landing on the spot is what you want.
Land and throw everything at stopping - spoilers, brakes, reverse.
Exit runway if possible, but do not taxi to the ramp.
Complete hot brakes checklist.
Think aloud throughout - for the benefit of the tape.
Complete paperwork as to why you did not have the full performance ‘buffers’.
Tech Log entry to change brakes, wheels, tyres or whatever MOM calls for. Maintenance will want touch down groundspeed and rate of descent, so it is helpful if the FO can make a mental note of these. If not, give them PIDOOMA. or they can probably access it via QAR.
Been there and done it twice; both occasions the runway was limiting. One tyre fuse plug blew on one occasion, but only after we stopped.
Last edited by Mach E Avelli; 4th Jan 2019 at 20:30. Reason: Note to maintenance
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No matter, the "Runway length required" that Atlas Shrugged got and that was "well beyond the length of the runway" either does or doesn't include the extra pad, and its inclusion vs. exclusion drastically changes the picture.
If you don’t have enough fuel to divert, nothing changes, except perhaps whether you call it a Mayday and put the pax in the brace position. I would only be going to that extreme if the runway was so short that an over run was likely. In the case of Wellington and a B767 I rather doubt that.
But if an over run WAS clearly inevitable AND a longer alternate could be safely reached by ignoring the FL200 limitation, I would rather go to the alternate.
The FL200 limitation does not mean that the aircraft will crash if it is exceeded.
But if an over run WAS clearly inevitable AND a longer alternate could be safely reached by ignoring the FL200 limitation, I would rather go to the alternate.
The FL200 limitation does not mean that the aircraft will crash if it is exceeded.
Last edited by Mach E Avelli; 5th Jan 2019 at 03:22.
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Boeing NSB 12 bulletin ( Boeing 737)
2. Maneuvering during flap retraction from Flaps 1 to Flaps Up after takeoff
or during a missed approach when Engine Anti-Ice is ON or when Wing
Anti-Ice has been selected ON after liftoff.
NSB 12 describes nuisance stall warning stick shaker events that can occur under certain circumstances including item 2 described above, the mitigation is to reduce bank angle to 15 degrees.
2. Maneuvering during flap retraction from Flaps 1 to Flaps Up after takeoff
or during a missed approach when Engine Anti-Ice is ON or when Wing
Anti-Ice has been selected ON after liftoff.
NSB 12 describes nuisance stall warning stick shaker events that can occur under certain circumstances including item 2 described above, the mitigation is to reduce bank angle to 15 degrees.
The right set of circumstances could come together as the flaps are deployed
1. in the middle of the turn, G is increased to tighten it up for unforeseen (but foreseeable) circumstances
2. extra drag from the G slows the plane
3. extra drag from the flaps slows the plane
4. pitching moment from the flaps slows the plane
5. crew is too distracted by #1 to act on the speed decay vis-a-vis power or trim, and too task saturated from everything. They only pull back more on the yoke to counteract the descending tendency, thus slowing the plane more
Planes have been stalled for stupider reasons than that, so I believe it.
1. in the middle of the turn, G is increased to tighten it up for unforeseen (but foreseeable) circumstances
2. extra drag from the G slows the plane
3. extra drag from the flaps slows the plane
4. pitching moment from the flaps slows the plane
5. crew is too distracted by #1 to act on the speed decay vis-a-vis power or trim, and too task saturated from everything. They only pull back more on the yoke to counteract the descending tendency, thus slowing the plane more
Planes have been stalled for stupider reasons than that, so I believe it.
You can’t compare a multi engine jet with a light SE.
In a light GA aircraft you simply don’t have the excess power or performance.
Inexperienced pilots or pilots with very marginal currency should avoid flap extension or retraction in a turn. Climbing or descending.
I always instructed my students not to do it.
During a turn you should be concentrating on other things and aerodynamic changes are a distraction.
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If you don’t have enough fuel to divert, nothing changes, except perhaps whether you call it a Mayday and put the pax in the brace position. I would only be going to that extreme if the runway was so short that an over run was likely. In the case of Wellington and a B767 I rather doubt that.
But if an over run WAS clearly inevitable AND a longer alternate could be safely reached by ignoring the FL200 limitation, I would rather go to the alternate.
The FL200 limitation does not mean that the aircraft will crash if it is exceeded.
But if an over run WAS clearly inevitable AND a longer alternate could be safely reached by ignoring the FL200 limitation, I would rather go to the alternate.
The FL200 limitation does not mean that the aircraft will crash if it is exceeded.
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You might be right, but might be wrong. For my aircraft Embraer decided that flying above FL200 with flap out was too dangerous because of critical mach and buffet problems. They state multiple times in the AOM (and my airline repeats in SOP) that this limitation is not to be exceeded. The QRH says in all instances that if we have a flap retraction issue that FL200 is our top altitude.
Fixed it for you:
What you meant to say was "mine didn't crash"
Your embraer won't crash. Don't ask how I know.
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The original reasoning behind the 20000 ft limitation for flap extension (for Boeing at least) was that there was such a small probability that flaps would ever be required above that level, there was no point in extending the test program to validate handling. Perhaps Embraer thought the same. Certainly, had their aircraft exhibited any undesirable handling at FL200 during the test program, they would have either addressed it, or imposed a lower flap extension limit to provide a safety buffer.
Built-in asymmetry protection is expected to safeguard handling if the flap system goes out to lunch, but can't be expected to cover cases of other structural failure. One such case occurred with an old B732 which had the L.E. slat on one side partially break loose and wrap itself back over the wing during a missed approach. The crew found themselves in the classic 'between a brick and a hard place' situation. They could not land at the destination because the weather and runway length etc made that far too risky. But as they climbed out to divert to the alternate the aircraft quickly reached a speed where roll control was no longer possible. Fortunately, by very careful handling of speed, altitude and thrust they did make it to the alternate, but ate into their final fixed fuel reserve to do so.
A crew fixated on observing all limitations may well have decided to ditch. In the dark, over open sea, that would have been a far worse outcome.
Built-in asymmetry protection is expected to safeguard handling if the flap system goes out to lunch, but can't be expected to cover cases of other structural failure. One such case occurred with an old B732 which had the L.E. slat on one side partially break loose and wrap itself back over the wing during a missed approach. The crew found themselves in the classic 'between a brick and a hard place' situation. They could not land at the destination because the weather and runway length etc made that far too risky. But as they climbed out to divert to the alternate the aircraft quickly reached a speed where roll control was no longer possible. Fortunately, by very careful handling of speed, altitude and thrust they did make it to the alternate, but ate into their final fixed fuel reserve to do so.
A crew fixated on observing all limitations may well have decided to ditch. In the dark, over open sea, that would have been a far worse outcome.
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