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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, 05:24
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Beau_Peep
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Will you retract slats/flaps in windshear?

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.

In my opinion, FD guidance will adjust accordingly to prevent such speed excursion, so I shouldn't retract the slats/flaps and stick to the written procedure.

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, the time when Instructor wished I should have retracted the S/F

I wish to know if you had similar experiences and your useful opinion

Last edited by IFLY_INDIGO; 25th Feb 2015 at 16:11. Reason: clarification
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Old 25th Feb 2015, 05:35
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No, not until clear of shear and at a safe altitude
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Old 25th Feb 2015, 05:56
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so I shouldn't retract the slats/flaps and stick to the written procedure.
Good idea. Ask Bloggs what he would suggest you do if, after having rectracted said flaps/slats (and probably not damaging them) you then suddenly fly into the opposite tailwind shear. Extend them?
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Old 25th Feb 2015, 06:19
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Maintain configuration.
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Old 25th Feb 2015, 06:22
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IFLY_INDIGO
There is dilemma here because you mustn't change configuration that is definite but you should not damage your flaps. The correct and safe way of saving the flaps is to fly above the flight directors to convert speed into height and when the speed trend reverses again fly the FDs. This might get you out of wind shear itself. This is airbus recommended procedure.
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Old 25th Feb 2015, 06:25
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I suggest you might like to ask the Instructor to show you the data on the aircraft’s windshear response that he/she has produced, which overrides that produced by the aircraft manufacturer who designed it (aided by massively powerful computers and very clever people) the aerodynamicists who wind-tunnel tested it, and the Regulatory Authorities who certified it.

He or she must be one very wise person if they are able to debunk the universal industry-standard procedure – to NOT reconfigure in windshear. Very impressive ….
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Old 25th Feb 2015, 06:25
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Will you retract slats/flaps in windshear?

FD will not prevent flap speed exceedance
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Old 25th Feb 2015, 06:32
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Isn't the speed increase a sign that the wind shear is over? Ok, there may be a second speed loss etc. but at some point one finally has to resume normal ops...

I would also be careful about pitching up above the FD. IIRC SRS w/s recovery mode limits the pitch to 22 degrees (or thereabouts) pitching significantly higher than that could put the a/c in an undesired energy state...

Also, a minor flap over speed is no drama - wings won't fall off...
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Old 25th Feb 2015, 06:34
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at first blush I thought you did the correct thing, then I realized if you had gotten your speed and altitude and had escaped the windshear, then you should start to clean up.

so, what altitude and what airspeed were you ?

and when did you start cleaning up?

For example, if you were over 1000' agl and in a normal climb profile, maybe you should have started the flaps up.

So, we really need quite a bit more info.
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Old 25th Feb 2015, 06:51
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We had a similar scenario last year followed by some casual opinions about retracting flaps during a huge speed excursion.

My attitude towards that is they make flap components every day. Microbursts less than once a career.

F and S speeds are weight dependant. Placard speeds are not, but even there some statistical margin exists.
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Old 25th Feb 2015, 06:53
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Potential flap damage due to slight overspeed is minimal compared to fuselage contact with ground due to loss of control.
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Old 25th Feb 2015, 06:56
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This is your captain Obvious speaking: universal procedure is to maintain config until absolutely sure you have escaped windshear.

I find option "Find more posts by" quite useful.
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Old 25th Feb 2015, 07:22
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Clandestino

I find option "Find more posts by" quite useful.
Y-e-e-s, I see exactly what you mean ....
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Old 25th Feb 2015, 08:02
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Rapid speed increase is not a sign of being out of shear only sign of wind direction/speed change. That's what windshear is And there is no guarantee it will be little overspeed. It happens in SIM and what I stated is how Airbus teaches.
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Old 25th Feb 2015, 08:32
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That is a case of negative training!!!

The procedure is very specific. Passing S speed is not a command for retraction in a windshear. Exceeding VFE, that is a different story.

The procedure says, DO NOT CHANGE CONFIGURATION (SLATS/FLAPS, GEAR) UNTIL OUT OF SHEAR

Were you out of shear? Oh, and also you don't have to retract flaps/slats when passing S speed in case of turbulence, you can delay that 20 kt or VFE -5 kt, If I recall correctly. That situation was, at least, turbulence.

and at the end: RECOVER SMOOTHLY TO NORMAL CLIMB OUT OF SHEAR

Stick to the memory items until out of shear. Speed increasing very fast towards VFE, with imminent penetration in overspeed, then you can continue with the "normal" climb: THR CLB, retract slats/flaps (and don't forget L/G if that is the case!).

Some say retarding thrust is the last, but it is not written anywhere. The primary thing here (after avoiding crashing into terrain) is not to exceed a limitation.
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Old 25th Feb 2015, 10:47
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Dear-oh-dear...
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Old 25th Feb 2015, 12:42
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The question is whether you are out of wind shear. If not leave that LVR CLB flashing, flaps, gear everything as it is. You can control speed by pitching just above the FD. You should not bring the thrust levers back unless out of it. Another thing is what was the acceleration altitude. If it was low as 800ft. then in any case you will have to ignore the FD once SRS changes to CLB and pitch up to keep climbing because FDs will come down to give you acceleration .
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Old 25th Feb 2015, 13:48
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A subtle note to your training provider regarding the accuracy of the mentioned trainer's point of view would be a suggestion.
It:
  1. Clears up the answer in their response
  2. Highlights the accuracy of the trainer's knowledge
  3. Prevents further anomalies to be instructed on this subject to other crew
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Old 25th Feb 2015, 15:01
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The industry standard, based on extensive research and manufacturers input, is to retain the existing configuration; AC 00-54.

If there is a guidance system, AP or FD, then use it. The manufacturer’s certification tests should have considered speed excursions during certification, i.e. probability of flap exceedance vs damage, or likelihood of encountering such a gross speed deviation vs the survivability in such a severe encounter.

In this (Windshear-Encounter) the crew followed the required recovery procedure (no computed guidance) and survived. Also, note that the FDR analysis showed that this actual encounter was very similar to the FAA simulated training model which was based on the infamous DFW accident.

Also see https://www.scribd.com/doc/232325774/Windshear
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Old 25th Feb 2015, 15:44
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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.

In my opinion, FD guidance will adjust accordingly to prevent such speed excursion, so I shouldn't retract the slats/flaps and stick to the written procedure
Following the FD "in windshear" can mean a number of things. Was the Windshear encounter determined by the Windshear Warning (in which case FD gives appropriate guidance)? Or "pilot assessed", when you just get normal SRS commands?

You then have the Aa issue, where the FD might change to CLB, but if still in windshear, it might be inappropriate to follow it.

Bottom line though is if you have not yet clearly communicated between the crew that you are clear of the shear, and adopted an acceleration profile, then you maintain config from my training.
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