Flaps 30 Go-Around in Severe Windshear — Is Flaps 15 a Valid Option?

[Amadis of Gaul]

Originally Posted by joshuahsong

Luckily, I’m not under any pressure from my company. What I keep wondering is when I run into a similar situation next time, how far I can step away from Boeing’s WEM procedure without getting into trouble.

I've been an airline pilot for almost 19 years now with three airlines. In those 19 years, I received a windshear warning exactly 3 (three) times, 2 (two) on approach, 1(1) on takeoff. Of the 2 approach ones, one was definitely false, one was probably false. The takeoff one was the only one that was legit.

My point is I doubt you have a pressing problem here. You may not see another warning for years, if at all.

[Chesty Morgan]

It's the things that happen the least often that need the most thought and the most preparation for.

[Bullethead]

What we are talking about here are really two separate maneuvers, firstly a Windshear Escape Maneuver, during which the configuration should not be changed, and then once clear of the windshear transition into a go around with the resultant configuration changes.

A minor flap overspeed is really little cause for concern but trying to overthink the situation in the heat of the moment can lead you into trouble you don't need.

Regards,
BH.

[olster]

I think it is unwise to go against manufacturer’s guidance underpinned by company sops reinforced in training. A flap over speed within limits is fairly innocuous in terms of post flight engineering inspection. Secondly the B737 has Flap Load Relief which should alleviate any over speed margins. With respect I think the OP is overthinking this. Company and blame culture is another matter which I’m not going to comment on!

[Amadis of Gaul]

Originally Posted by Chesty Morgan

It's the things that happen the least often that need the most thought and the most preparation for.

I agree. Unlike, say, finishing a sentence with a dangling preposition, which seems to happen all the time.

[Chesty Morgan]

There is no rule against doing so and the need to avoid doing so is rejected by modern language authorities as it is based on Latin grammar and not English.

But, like everything else, I'm sure you knew that.

[Amadis of Gaul]

Originally Posted by Chesty Morgan

There is no rule against doing so and the need to avoid doing so is rejected by modern language authorities as it is based on Latin grammar and not English.

But, like everything else, I'm sure you knew that.

I did not know that. English is my fourth language, I'm barely getting by over here.

[joshuahsong]

Originally Posted by Amadis of Gaul

I've been an airline pilot for almost 19 years now with three airlines. In those 19 years, I received a windshear warning exactly 3 (three) times, 2 (two) on approach, 1(1) on takeoff. Of the 2 approach ones, one was definitely false, one was probably false. The takeoff one was the only one that was legit.

My point is I doubt you have a pressing problem here. You may not see another warning for years, if at all.

​​​​​​​Thanks for sharing your experience. You’re right, windshear warnings don’t come up very often, and some of them do turn out to be false alarms. But the whole point of having SOPs and QRH maneuver instructions is that when real windshear does happen, we don’t waste time thinking. We just act.

Even if the odds are low, the consequences of getting caught in actual windshear are serious, so consistency in procedures matters more than frequency. I think that’s why the industry emphasizes rote responses for things like WS, RTO, and GPWS.

And in my case, it was an actual windshear. Also during the approach, I heard my preceding go around because of a windshear warning.

[Centaurus]

Originally Posted by BraceBrace

I think you are using bad examples here... Did those accidents involve windshear?

FD is a primary guidance. The QRH is clear that an initial pitch up to 15° is required. When the speedbrakes are confirmed retracted, the FD becomes primary _guidance_. If you don't focus on correct pitch, "the nose is everywhere and nowhere" because people chase other instruments. You better make people follow the FD as is expected by Boeing "within a certain pitch range", and not chase other instruments. That is also explained in these words in the procedure: "Intermittent stick shacker or initial buffet is the upper pitch attitude limit" (or pitch limit indication). The PF does not need to do anything else.

The _PM_ has to monitor vertical speed and altitude, callout trends towards terrain or _significant_ airspeed changes. But the ACT of flying is done through pitch. The standby ADI should NOT be glanced at, for no single reason other than IRS failures. The ASI should not be taken "literally" but used for tendencies as the speed in a violent windshear can be all over the place. The word by Boeing for PM to make a callout is correctly "significant".

Secondly, GPWS warning recovery is NOT a FD guided maneuver.

Thanks Brace Brace. I stand to be corrected. It has been many years since I flew a 737 and a bit out of touch with all the new avionics. The previous accidents I referred to were all loss of control although windshear was not a contributory factor.

[Propellerhead]

Some good advice already, so to summarise :

“Windshear x 3” warning (reactive / immediate warning) : do the WS escape manoeuvre - do not change flap under any circumstances until clear of WS and then perform a normal G/A.

“Go-around, WS ahead” or “monitor radar display” : ideally a normal GA and turn to avoid (flap 15). However if you encounter actual wind shear then do WS escape.

If you ‘pilot detect’ actual WS (conditions listed in QRH) do the WS escape manoeuvre.

For me the grey area comes if you get positive shear first - that’s what happened to me once - the thrust levers were coming back and speed going up so I actually called “unstable go-around” and did a normal go-around. During that got the negative WS and reactive WS warning so converted into WS escape. The point is if you’re not sure and you’re not receiving a reactive warning then a normal go-around is a good option - pressing TOGA and getting the aircraft climbing away at 2000ft/min is a pretty good starting point. And if you’re doing that you’re not in negative WS!

[vilas]

. In a scenario like mine—where the aircraft was already above 500 ft AGL, with a strong positive climb rate (more than +2000 fpm and stable)—would it make sense to select Flaps 15 to prevent exceeding the flap placard speed?

main risk with reactive windshear is uncontrollable descent and terrain contact. Increasing speed and strong climb is not an issue. In a windshear a pilot should be too happy with +2000ft climb. To avoid overspeed all he has to do is to just pull up and bring the speed back. This high ROC may even take the aircraft out of windshear itself. Why bother about flap at this stage? On the other hand falling airspeed and descent is a serious issue and tricky to handle. You may have pull back to stop descent till stick shaker and fly with intermittent shaker on and hope gust changes direction to allows to resume climb at normal speed.