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Will you retract slats/flaps in windshear?

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Will you retract slats/flaps in windshear?

Old 25th Feb 2015, 16:10
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Beau_Peep
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clarification for better response:
We entered into windshear immediately after take-off - red WINDSHEAR warning with audio.
Speed excursion was momentary. Speed decreased below S after the excursion. So we were NOT out of windshear when instructor wished I should have retracted the S/F
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Old 25th Feb 2015, 16:55
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Similar to what was mentioned before, stick shaker just after takeoff because you got an airspeed loss after previously having a gain and retracting flaps is not a nice idea at all. Would much rather exceed flap limits and deal with whatever that might bring (IMO probably nothing unless something really weird is happening).

As an anecdote, a company I previously worked for (flying something single pilot and lighter) had a pilot who for over a year didn't know what the limiting speeds for the first couple of stages of flap, and exceeded them probably numerous times a week until he finally did the same thing on an OPC.
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Old 25th Feb 2015, 18:17
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Recently, I had a sim session and handled a windshear exercise immediately after T/O. Airspeed went way above S momentarily while I was maintaining FD.

After completion of the session, Instruction debriefed that I should have retracted the slats/flaps to prevent damage to them.
Did your debrief discussion include a review of the written procedure? What does it say? Was his assertion in line with, or contrary to, the written procedure?

In general, as others have said, the windshear escape maneuver is done with NO configuration change other than retracting speedbrakes, if extended. There is likely NO note that says to retract flaps if the airspeed momentarily exceeds the current flap speed during the shear. One reason is that the airspeed is likely to reduce to BELOW the safety speed for retracted flaps, BEFORE they are even fully retracted!

IF the instructor's assertion was contrary to the written procedure, you should make a written report to the training center for which he works, reporting his contradiction of written procedure.

While the windshear is occurring, flap damage is NOT your primary concern -- staying out of the dirt is! Don't make up procedures, or allow bad instructors to lead you into made-up procedures! Does your procedure tell you to follow the FD, or to pitch to a certain limit (e.g., pitch angle or stick shaker)?

OK465: ESPECIALLY immediately after takeoff, retracting flaps is NOT a good idea. The momentary speed excursion is VERY likely to reverse; and if the flaps are retracted, stall is MUCH more likely. While there MIGHT be a valid discussion in some airplanes regarding flap position vs climb performance (e.g., FLAPS 10 vs FLAPS 20 in the 747), there is a MUCH higher likelihood of a WRONG change being made in the heat of the moment.
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Old 25th Feb 2015, 18:36
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Flap exceedence is an easier write-up than an obituary. Your instructor sounds like he has too much time in the cubicles thinking of minutiae.
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Old 26th Feb 2015, 03:22
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Exactly. You don't care about your flap limitations when in a windshear situation close to the ground. You try to prevent the crash and worry about flap speed exceedences later which will most likely have not caused any damage anyways.

Once safely clear of the windshear worry about configuration.
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Old 26th Feb 2015, 03:42
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Also remember that S speed is not the only condition for retracting. The trend arrow should be showing acceleration and if you are in turbulence, you may delay retraction 20 kt or VFE-5 kt. If trend is erratic, you are in turbulence and speed may well go below S again.

If on top of that you have a RWS going on, man… The procedure is crystal clear.

You had some negative training that day. It happens from time to time.
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Old 26th Feb 2015, 05:46
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Windshear, fly escape maneuver, maintain configuration, end of discussion.
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Old 26th Feb 2015, 10:06
  #28 (permalink)  
 
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Originally Posted by OK465
The guidance to not change configuration is a one-size-fits-all, current best practices remedy to prevent potential misjudged aggravation of any windshear situation, but I don't think anyone would ever claim that there are not isolated instances where a change of configuration might improve end game flight margins. Staunch procedural guys can gasp and tsk-tsk all they want here
True, but currently the only technology available to identify such cases is hindsight. Might change with lidars coupled to performance computers but the time passing between Ueberlingen and TCAS 7.1 gives me no reason to be optimistic.
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Old 26th Feb 2015, 10:15
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I know nothing about Airbus's but purely from an airmanship point of view Id suggest that your instructor/checker doesn't know what he's talking about. Frightening actually.
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Old 26th Feb 2015, 18:39
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Boeing procedures is to not change configuration and I belive that is mainly due to the fact that things moving in an airstream produce more drag than stationary things.

If flown properly and the thrust managed you should not exceed any limits however it's not deadly if you do, retracting the high lift devices against the manufacturers recommendation based on a fear of breaking them is ludicrous. Let me ask you this, how long do they take to retract, do you have any hope that they would have fully retracted before the exceedance occurs.

Our procedures require f5 takeoffs and to get the LE devices in would require the selection of flaps up, not sensible considering large speed variations and the time it would take.
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Old 26th Feb 2015, 20:49
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Stator vane

With 26 years in civil aviation, may I wholeheartedly endorse your comments, though my slightly more graphic remarks yesterday evening obviously offended the mod(s) and were excised!!!

There are too many 'trainers' out there who vary from being an irritation during OPC/LPC checks to those who are positively dangerous, leaving ordinary capable line dogs demoralized and sometimes confused on points of technique or procedure.

How often have I heard the question " WHO told you THAT?" etc etc

And some in these fora have the effrontery to criticise other cultures' training regimes whils the most appalling rubbish gets pushed in EASA supervised & approved airlines!
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Old 26th Feb 2015, 21:41
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IFLY INDIGO...CONGRATULATIONS! You must have aced the totally unexpected and extremely worst case windshear scenario that your instructor was utterly gobsmacked that he only wanted to bring you a few notches down.

There are many Alteon instructors like that. If you do so well in a check item, they will come up with very devious " shock and awe " failures to make you sweat and puff. Just KNOW that you had the best of him/her, come away with a glow and a smile!
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Old 26th Feb 2015, 22:26
  #33 (permalink)  
 
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Use SPD brakes
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Old 26th Feb 2015, 22:41
  #34 (permalink)  
 
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Though I'm not a pilot, to me changing aircraft configuration in the middle of a windshear defies common sense.

If it were me, I think I'd respond to the instructor something to the effect of "I've always been taught to not change configuration during a windshear upset, could you please provide a reference for this 'new to me' procedure so I can investigate further?"
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Old 26th Feb 2015, 22:57
  #35 (permalink)  
 
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S speed is not a limitation, it is the lowest speed at which you can select flap 0. Many have already posted the obvious, that changing configuration is a dangerous, ridiculous idea.

Some things I have done with sudden speed increases associated with windshear:

1. Convert the momentary speed increase into altitude, i.e. pull up above the FD demand. Be careful not to overdo it though.
2. Momentarity reduce the thrust a little, to approx 65-75% N1, if you're aboslutely sure that the speed trend is positive and you are going to overspeed. You can always put the thrust back on quickly, something you can't do if you start retracting slats. Obviously don't go anywhere near idle as it would take longer to get max thrust back.

Finally, as has already been mentioned a 10-15kts overspeed won't break the wings off whereas impacting the ground will.
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Old 27th Feb 2015, 07:32
  #36 (permalink)  
 
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I would go for the 'speed for height' exchange as well. It's all about energy management and survival. Do you consider raising the gear as a change of configuration? I would allow that as the increase in performance might just save the day. Some say that ground impact would be softened with gear down, but with it retracted it might not happen at all. You choose.
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Old 27th Feb 2015, 09:31
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Windshear recovery is solely about Energy Management. The Windshear has the potential to render your current PE + KE inadequate for flight i.e. KE to keep flying leaves PE as underground

The way I see it, your aims:
  1. ADD as much Energy as possible = Full Power, no speedbrake
  2. OPTIMISE your KE v PE balance, essentially means keep KE close to, but above minimum speed which equates to max PE (Height) - negative PE is not good for your health
Refinements such as gear up, more flap might, with hindsight, save the day, but you need a simple reliable drill.

If following the FD leads you to have excess speed, either:
  1. The FD is not giving you the correct Windshear profile = ignore/deselect it, pull nose higher for PE v KE
  2. The Windshear is significant, and the "gain" you are seeing may well be reversed - it is not a "good" sign
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Old 27th Feb 2015, 13:27
  #38 (permalink)  
 
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RAT 5 - retracting the gear will open the gear doors and add a whole lot of extra drag just when you don't need it. We are told to leave it well alone and I agree.
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Old 27th Feb 2015, 14:30
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windshear escape must be predicated on KISS

(kiss: keep it simple stupid).

IF you want to get fancy and go against KISS, you could turn off the bleeds and generators and get more thrust from the engine. Not many of us could do that while trying to fly the plane, so KISS.

An overspeed, but otherwise successful windshear escape maneuver, is a success. But certainly, once clear of windshear, clean up and throttle back.
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Old 27th Feb 2015, 16:08
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@Zippy, that depends on type. On the 737 the gear doors are already open anyway.

But, as pointed out above, it is a KISS example across types and therefore it probably is better to keep to the basics and simply fly out of it before worrying about configuration.
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