NTSB: Speedbrakes not armed before Southwest 737 excursion

[SpauldingSmails]

Sure, airplanes can't save us from ourselves in all circumstances. I'm sure the two gents sitting in the front of that 737 at MDW staring at the boundary wall were saying "coulda, shoulda, woulda..." If the spoilers popped on touchdown, or as you contend, had immediately deployed the reversers all probably would have been well.

Point being, if other aircraft, namely smaller and less expensive ones can have near fool-proof air/ground logic with regard to landing and stopping its surprising that Boeing did not incorporate such into their latest iteration of their best selling aircraft.

Yes, I understand the commonality, certification and so and so forth blah blah blah ... and that is the way it is.

 

[NEDude]

Not being critical, just trying to understand the circumstances: It took them 16 seconds to deploy the reversers after landing. If my memory serves correctly didn't the 2005 overrun have similar circumstances in that the pilots took quite a while after touching down to deploy the reversers? Is there anything in the pilots statements that indicate why it took so long?

 

[Golden Falcon]

It was a windy crapy wet day in MDW with flaps 40. An overspeed happens.

Never flew the 737, only 75/76...VREF even at max landing weight was well below flap limit speeds...thats why I commented it APPEARS to have been/gone unstable....not sure of their stability criterion/limits at SWA so not criticizing, just inquiring...

 

[igneousy2]

first, I don't think we want these systems too automatic...i've had some crazy things happen with computers on various airplanes including the PSEU on the Boeing...that's all I need is for the spoilers to deploy at cruise because of some PSEU fault. I think it's one of the nice features of the 737 is that not too many things happen by themselves.

That being said for those critizing the 737...it does deploy automatically without arming when you engage the reversers.

We shouldn't be like the cubical pilots, the feds, and the general public...not every accident and/or mistake requires a whole redesign of an airplane or a wholesale change in procedures. I don't know what SWA landing checklist procedure is, but has anyone considered that maybe the cause is there is too much call outs flows and checklists going on?

I think it was NASA or maybe UND that did a study that found that once you get beyond 5 items on a checklist the probability that something will be missed on that checklist goes up rapidly the more items that are on the checklist...and there is no difference between items as to what is going to be missed...in other words...make sure checklist items are only the most critical stuff. I've seen some airlines with 10 items on there landing checklist. 737 should just be Gear - 3 green, Flaps-Set, Spoilers Armed...what else do you really need?

One technique that I see a lot with our old -200 Captains is they move there hand from the power levers to the speed brakes on touchdown. I think on the 200's the spoilers would sometimes snap back pretty quicklly and this was an attempt to slow them down. I think this technique might have helped in this situation as the Captain would have known immediately that the brakes didn't come back.

 

[The Prussian]

Never flew the 737, only 75/76...VREF even at max landing weight was well below flap limit speeds...thats why I commented it APPEARS to have been/gone unstable....not sure of their stability criterion/limits at SWA so not criticizing, just inquiring...

Golden...easy enough to do. Say Vref is 128 and add 5 on a calm day is Vtarget 133...no problem with Flap 40 overspeed being 156. But on a crappy day Vtarget becomes 148 (add steady state plus 1/2 the gust...max additive 20 kts). Coming down final targeting 148, and a sudden 10 kt gust could put you 2kts over the 156 kt limit.

 

[humveedriver]

Golden...easy enough to do. Say Vref is 128 and add 5 on a calm day is Vtarget 133...no problem with Flap 40 overspeed being 156. But on a crappy day Vtarget becomes 148 (add steady state plus 1/2 the gust...max additive 20 kts). Coming down final targeting 148, and a sudden 10 kt gust could put you 2kts over the 156 kt limit.

If its that gusty I would probably recommend flaps 30 anyway. Also, Boeing recommends no Vref additive landing with auto throttles on. I find adding knots in a gusty crosswind makes me float in the -700. What seems to help is keeping the power in as long as possible, even above idle at touchdown. That vertical stab is an anchor on a good crosswind. YMMV, there are a thousand ways to land an airplane.

 

[scoreboardII]

If its that gusty I would probably recommend flaps 30 anyway. Also, Boeing recommends no Vref additive landing with auto throttles on. I find adding knots in a gusty crosswind makes me float in the -700. What seems to help is keeping the power in as long as possible, even above idle at touchdown. That vertical stab is an anchor on a good crosswind. YMMV, there are a thousand ways to land an airplane.

you won't be landing much at MDW then, most every landing is F40 to get stopping margin, yes, just that extra couple hundred feet.

 

[vixin]

To get the margin with a wet runway, gusty, auto breaks required, 40 at MDW is needed. We (SWA) do not use A/T on landing. They need to be off with the auto pilot.

 

[Quimby]

If its that gusty I would probably recommend flaps 30 anyway. Also, Boeing recommends no Vref additive landing with auto throttles on. I find adding knots in a gusty crosswind makes me float in the -700. What seems to help is keeping the power in as long as possible, even above idle at touchdown. That vertical stab is an anchor on a good crosswind. YMMV, there are a thousand ways to land an airplane.

Keeping the power above idle at touchdown?



Why?

 

[humveedriver]

Keeping the power above idle at touchdown?



Why?

Just a bit. When you transition from crab to wing low it keeps the plane from crunching. We're talking crosswind over 30 knots. SWA uses different landing data and procedures, so roger on the flaps 40. I think the braking action was reported as fair. So 30 may not have been an option using aero data either. At any rate these guys would have been fine if they had spoilers or reverse. They didn't have either one, so it doesn't matter how smooth the flare and touchdown was. The sudden stop at the end is what ruined there day. Not a momentary flap overspeed which is a non event.