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Will you retract slats/flaps in windshear?

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Will you retract slats/flaps in windshear?

Old 27th Feb 2015, 17:09
  #41 (permalink)  
 
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NOD, energy management might not be as simple as you imply (#40). Depending on the type of detection and guidance system, the form of energy management could be proportional to height above ground.
With relatively large ground clearance (according to aircraft, excess energy, etc) the guidance system is biased towards higher speeds to help transit the shear, whilst still climbing.
As height reduces, speed is traded for climb to maintain ground clearance; in some systems airspeed is traded such that at ‘ground contact’ airspeed=Vs.

An optimised guidance system should not exceed flap limit speeds, but could exceed retraction speeds. These aspects are not assured as many windshears can induce large and rapid speed reversals where the guidance / aircraft are incapable of reacting in such a short time.

In the previously linked incident (no guidance system), the crew were required to make rapid attitude changes – some significantly lower than expected, just to maintain their target airspeed (Vref). The focus of their attention was attitude and speed with little or no capability to consider anything else. The Captain was one of the most experienced on the aircraft type and in the operating environment.

Those who wish to discuss how to handle a shear immediately after take-off might consider why the conditions relating to shear were not identified before take-off.
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Old 27th Feb 2015, 17:47
  #42 (permalink)  
 
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Forgive me for copy paste of the systems manual, but...Firstly the original poster basically asked if the sim instructor was correct.. in short No
Secondly, a well posted this is an " escape manoeuvre " not an exercise in advanced airmanship..
Boeing and Airbus have developed the shortest format of the tried and tested procedures in the QRH, on the whole, the automatic guidance systems do a better job than us, excepted autopilot struggles..
Of course, in dire straits if the system is not giving us what we want ( for some unknown reason), we are pilots, just do the best we can.
Changing the configuration by raising the gear will result in more drag as the whole wheel well is exposed, equally , raising flaps changes the stall indication logic and during flap transit the signals are unreliable ( there is a Boeing memo on this regarding false stall warnings)
KIS
"If windshear is encountered during F/D takeoff or go–around, the F/D pitch command bar provides commands to maintain the target speed until vertical speed decreases to approximately +600 fpm. At this point, the F/D pitch bar commands a 15 degree nose–up pitch attitude. If vertical speed continues to decrease, the F/D continues to command a 15 degree pitch attitude until a speed of approximately stick shaker is reached. It then commands pitch attitudes which result in intermittent activation of the stick shaker. As the airplane transits the windshear condition, the F/D programming reverses. As climb rate increases above approximately +600 fpm, the F/D commands pitch attitudes which result in
acceleration back to the target speed. The A/P and F/D both operate in a similar manner during A/P or F/D go–around."
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Old 27th Feb 2015, 18:41
  #43 (permalink)  
 
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Changing the configuration by raising the gear will result in more drag as the whole wheel well is exposed, equally , raising flaps
that's a lot of interesting things I know nothing about. however in a windshear situation applying max available thrust and focus on flying the aircraft instead of worrying about changing the configuraturation, with possibly minimal benefits sounds like the right thing to do. A and B a/c have very impressive thrust to weight ratios. Whoever is making up their own procedures, against manufacturers recomendations, is probably thinking of some light a/c
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Old 1st Mar 2015, 10:41
  #44 (permalink)  
 
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Screw The Flaps!

I must agree with most, DeeJayPee said it short and tight. I'll expand a little:

Windshear at low levels can and will kill you. In a W/S event the ONLY thing that you really want is increased (stable) forward speed... deal with the other details later. If, during your recovery, you happen to over-speed a particular flap setting, Mx will inspect and repair as necessary. (That may be a huge job, but it is better than buying a new airframe and/or paying the death claims, including yours.) Put differently, during a low-level W/S event, your sole, ONLY ficus should be on FLYING your airplane - and keeping it flying. What is more important? Firewall the SOB, override everything within your control and pray that you get get enough thrust, soon enough to keep your bird flying. If you have some ability to exceed TOGA, use it, now. The alternative may be a tombstone suggesting that "...he preserved the flaps and slats, but killed himself and 150+ others...)

W/S at low level is never a joke. IMO only, safest course out is a LOT more forward speed and perhaps increasing speed. Whatever you need to do or can do to achieve that speed, quickly, is easily worth the cost of a part or two that you may damage, to and including the little blocks that stop the thrust levers and the forward extreme. Other than for terrain, you cannot turn and all you want is higher forward speed, eventually giving you the ability to stay level or climb. IN the first few seconds, the back-hanging flaps may help you. Once you have achieved a secure manuvering speed, probably well above minimum, consider cleaning up a little, adjusting your makeup, changing your shorts etc. Until you have recovered significant forward speed, NOTHING else matters.
Some may blast my direct approach and that's OK. I remind them that forward speed, air passing over that wing fast enough to provide some degree of lift is your only instant concern. After than is achieved and you have verified positive control, perhaps you can consider adjusting those little extras on your wing or even the thrust.
without significant forward speed you will not fly. If you are in the air, ,but not flying, the ground will approach, probably sooner than you would like.
The take home: If W/S is known or suspected, and RW length permits, stay hot, land with power on and be ready to goose it. If other conditions do not permit such a landing, let's hope you have planned a reasonable alternate: bug out and find a different slab... Opinions can and do differ. With fuel available, I cannot imagine making a second approach into known W/S conditions; I'm gone.
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Old 1st Mar 2015, 12:42
  #45 (permalink)  
 
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I FLY INDIGO
your question was would you retract flaps when speed is increasing in wind shear. I told you Airbus procedure. I further give you a quote from their safety magazine. Changing configuration is a non standard not recommended dangerous procedure.
Recovery technique for wind shear encounter


The aircraft can only survive severe wind shear encounters if it has enough energy to carry it through the loss-of-performance period. It can sustain this energy level in the following three ways:


• Carry extra speed. The aircraft does this automatically when in approach in managed speed (Ground speed mini).


• Add maximum thrust. The aircraft does this automatically with alpha floor protection, even if TOGA was already selected (do not forget to disconnect the Auto thrust in this case, when out of alpha floor).


• If possible, trade height energy for speed. Any aircraft can do this.


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Old 1st Mar 2015, 12:45
  #46 (permalink)  
 
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Noflyzone,

Forward speed is important but most important is keeping your AOA at CLmax. That is fly high pitch, respect PLI and stall warning, and for the Airbus guys fly SRS or 17,5 deg otherwise. This in reasonable limits of speed of course. You don't pitch for speed otherwise you'll convert the aircraft in a submarine when in the negative side of a microburst.

See delta crash. They crashed with a lot of forward speed...

And no, don't touch the flaps, cause they keep you flying. If you think that you can remove some flaps due to speed, think that in the next seconds you might not have that speed!

Anyway, pilots fly memo items. Those procedures are written after a lot of crashes

Cheers

Last edited by Lantirn; 1st Mar 2015 at 12:47. Reason: Flaps
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Old 29th Dec 2015, 00:06
  #47 (permalink)  
 
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For me, there is no discussion about this. DO NOT CHANGE THE CONFIGURATION. That's what the manuals say. The instructor was wrong.
Worry about an assumed damage in the flaps while you are passing through a low level windshear ?
This sounds stupid to me.
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Old 29th Dec 2015, 05:51
  #48 (permalink)  
 
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Thanks

Thanks for sharing those valuable links
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Old 29th Dec 2015, 07:34
  #49 (permalink)  
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Some interesting, if concerning, comments and suggestions.

Keep in mind that, for an event such as ..

Speed excursion was momentary. Speed decreased below S after the excursion

... the airspeed system is not as reliable as normally observed. Works pretty well in steady state conditions which parallel the calibration data ..

At the end of the day, one trusts in the historical probabilities and research .. most times you win, very occasionally, you lose.

Winging things on the day is not all that useful in general practice ..

Best practice guidance is to follow the OEM's recommended practice ...
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Old 29th Dec 2015, 09:12
  #50 (permalink)  
 
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Windshear procedure is something we do when we are at a too low energy state, while we wait for the energy to come back. And it sure that it is going to come back. It is like we are surrounded by too many indians throwing arrows at us, but the cavalry is coming anytime. The game is not to die stupidly before the cavalry arrives.

The only thing that matters is not to lose altitude. Speed or any other thing is totally irrelevant during that time. Once the energy comes back, then you continue normally, retracting flaps and all.
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Old 29th Dec 2015, 10:44
  #51 (permalink)  
 
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Don't think about it, just do the memory drill ! DO NOT INVENT YOUR OWN PROCEDURES.

For example, as many have said, raising the gear adds drag, and moving any hydraulic item such as gear or flaps puts extra load on the engine driving the hyd pump.

Lots of folk at the manufacturers have spent time working out what is best to do in any situation, and their test pilots have flown each procedure and refined it so that the average line pilot can fly it safely.

As many have said, ask the instructor to show you where in the company or aircraft manuals what s/he says is written down. Or ask your chief instructor to clarify the procedure and when they ask you why, tell them what you were told and by whom.
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Old 30th Dec 2015, 14:03
  #52 (permalink)  
 
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Ah, yes, The Training Department Brainiac strikes again! Every airline has a few...
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Old 1st Jan 2016, 05:49
  #53 (permalink)  
 
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All the types I operated as an FE had the same windshear procedures. Maintain configuration and fly out. I would monitor that very carefully. I was bollocked once for exceeding engine limitations in a windshear exercise in the box. Informed that I had overboosted the engines. I told the instructor that I was unrepentant and in the real case I would have my size 9s behind the throttles. No point not using what you've got if you are still descending.
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Old 2nd Jan 2016, 00:39
  #54 (permalink)  
 
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Reduce power? Dumb idea. You need energy. That comes from high thrust.

If the speed is still increasing convert that to altitude gained. Beware of possible high pitch attitude and subsequent need to lower the nose, perhaps faster than normal.

Retract flaps at S? At low altitude in a w/s event? The instructor who said that should be fired.

Vfe is the planned limit. Approaching that increase pitch for altitude (2nd paragraph).

You can exceed Vfe. Not converting into altitude is as dumb as just watching the overspeed. Momentary can happen. Staying in an overspeed situation isn't flying the a/c correctly.

In a severe overspeed maintaining configuration and diverting with that flap setting might deserve consideration. Didn't a 737 overspeed do a g/a @AMS, retract the flaps, and then couldn't extend the flaps for the subsequent landing? Decisions, decisions...

You can, might, or will, lose altitude. That is the huge unknown. Keeping flying, and avoiding ground contact, are the goals. Not losing altitude is not a goal. It is at the whim of the wx gods at that momentum if a max performing a/c is still descending.

Last edited by misd-agin; 2nd Jan 2016 at 00:43. Reason: ...flying the a/c correctly. Added severe overspeed paragraph.
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Old 2nd Jan 2016, 06:23
  #55 (permalink)  
 
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This discussion was prompted by a remark of ignorant TRI. Windshear is a well researched subject and has established procedures. Any modifications from that is fraught with danger and definitely beyond the perview of a line pilot. Not changing configuration due to increase in drag/reduction in lift is an established procedure. That doesn't mean you just watch excess speed destroy flaps. Why won't you take care of it by converting speed into height because the higher altitude may take you out of wind shear itself. If it doesn't then when the trend arrow reverses again fly the FD again.
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Old 2nd Jan 2016, 08:36
  #56 (permalink)  
 
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Why won't you take care of it by converting speed into height because the higher altitude may take you out of wind shear itself. If it doesn't then when the trend arrow reverses again fly the FD again.


And once again the circle is complete as the conversation comes round to SCAN. This subject has been beaten to death o many other threads. Where do you monitor the relevant performance data during W/S? VSI, IAS & ALT. The FD will have IAS & then go into ALT ACQ---ALT HLD, perhaps depending on MCP window. Guys are taught, in W/S, to "fly the flight director". Initially this can be good, but then what? Converting speed to height, carefully watching for the reversal; seems OK. Then how do you know you are clear of W/S. There might have been a grating voice saying "windshear, windshear," but there isn't one to tell you "clear of windshear, clear." So you have to become a real plot again. OMG!

Last edited by RAT 5; 4th Jan 2016 at 11:42.
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Old 4th Jan 2016, 09:37
  #57 (permalink)  
 
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Sustained improvement in energy level displayed by increase in speed or ROC is an indication that you are out of W/S. In AB AOA protection takes care of lower end of the speed scale you need to take care of higher end if you get ALT* by moving the thrust levers to climb. If not in ALT* then in SRS the FMGS will take care of even higher end by increasing ROC.

Last edited by vilas; 4th Jan 2016 at 10:27.
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Old 5th Jan 2016, 12:56
  #58 (permalink)  
 
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Maintain configuration.

May I suggest you report your SIM instructor to your company for giving misleading information. Just have a look at American Airline's misleading information regarding flying through wake turbulence which inadvertently led the crash in 2001. Had that instructor (cannot remember his name now, something Van something) had been reported for telling crews to use aggressive rudder during wake turbulence after T/O, the crash may not have happened!
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Old 5th Jan 2016, 13:44
  #59 (permalink)  

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Harsh but true.
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Old 5th Jan 2016, 14:50
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Just have a look at American Airline's misleading information regarding flying through wake turbulence which inadvertently led the crash in 2001. Had that instructor (cannot remember his name now, something Van something) had been reported for telling crews to use aggressive rudder during wake turbulence after T/O, the crash may not have happened!






If you're going to make up history at least provide the facts to support you false allegation.


Tape #1 was Dec 1997. 38:40
Tape #2 was Mar 1999. 48:53


Where should I start researching, for about the 3-5x, for the statements you allege were made?
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