sw plane goes off the rnway in mdw

[Busdrvr]

Yes, apparently your Jepps are old. Even SWA can't fly to CAT III mins with a HUD without the approach being cetified to CAT III. Therefore, anyone else with autoland would have used it to land at midway.

The point concerning Autobrakes is this: Autobrakes start IMMEDIATELY upon landing, even BEFORE deployment of the TR's. The crew apparently stated that they started applying brakes immediately AFTER realizing they were having difficulty getting the engines in reverse. That would mean there was a delay in getting the TR's deployed AND in applying wheel brakes. In any case, use of autobrakes would not have resulted in a worse outcome, only a potentially better one. If you felt the autobrakes weren't working well, and applied brakes manually, then you would have gained whatever minimal stopping action that lose when you go completely manual and start to apply brakes at sone poin after touchdown (ie, not immediately).

The crew, to my understanding, did NOT use autobrakes, as it would have been a violation of SOP.

Could you clear up something for us, since no one at SWA seems to know.... What are the conditions that are required for TR deployment on the -300. the reason I'm wondering about the 300 is that SWA may have stipulate similar settings for it's 700 to keep fleet commonality. On the 200, the ground sensing swith was on the right main gear, but I think the 200 could deploy it's TR's with either the Right main gear strut being compressed OR the nose gear strut being compressed.

 

[BoeingBoy]

At least I got my laughs today.....

I guess our profession is being taken over by computer programers - if it's not automated it's can't be done by mere mortals.

Call me old fashioned....

Years spent flying 727's (no autoland, no autobrakes, no autospoilers) or 737-200's (no autoland) into places like ROA (5800 ft of runway at the time), CRW (6300 ft), MDW, DCA (6800 ft), LGA (7000 ft). In all kinds of weather. Being a mere mortal, how did I survive?

Years of sim sessions where I had to demonstarte the ability to hand-fly an ILS to 100 ft, then either land or go around. Didn't the FAA know I was only human? Maybe they figured it out - we don't have to do that any longer. It's much more important to demonstrate an ability to program the computers than it is to be able to actually fly the airplane.

Yes, call me old fashioned. A throwback to a time when automation was a tool to be used, not a crutch to be relied on. A throwback to a time when pilots were expected to perform at least as well as the automation.

Jim

 

[CaptianBoomer]

Busdrvr:

I disagree with your analysis.......autobrakes on every aircraft I have flown use a deceleration rate to determine how much pressure is sent to the brakes. On a BUS, the delay is two seconds for MED and 4 secs. for LOW. On a BUS, if you use LOW Autobrakes and lots of reverse, you might as well leave the autobrakes off because the deceleration rate for just reverse exceeds the LOW decel rate.

The B737 is no different, other that the settings and timing.

I would consider that a reasonable pilot, landing at MDW the night in question would have hit the brakes immediately after landing, reverse or not.

Further, the more salient part of the discussion should be if the crew followed SWA's contaminated runway guidelines for tailwinds. I can't land my aircraft with fair braking and more than a 5 knot tailwind component without being in violation of the standards set for landing on a contaminated surface.

Boomer

 

[FLYAWAY]

Contaminated runway = no wheel spin up = no auto spoiler deployment = no strut compression = no thrust reversers. All on a 6500' runway.

 

[KCFlyer]

Jim...in those days they called you a pilot. Today, they'd call you a cowboy.



Moderator comment: Please don't quote an entire lengthy post.

 

[BoeingBoy]

Yes, apparently your Jepps are old. Even SWA can't fly to CAT III mins with a HUD without the approach being cetified to CAT III. Therefore, anyone else with autoland would have used it to land at midway.

I wish I had my Jepps to reference - as I said, they're at the airport. If MDW has a CAT II or III approach, then I stand corrected on use of autoland for this approach. But if MDW doesn't have CAT II or III, then autoland is irrevelent - unless the -700 can do autolands with only a CAT I.

The point concerning Autobrakes is this: Autobrakes start IMMEDIATELY upon landing, even BEFORE deployment of the TR's.

Correct, but that doesn't mean that the ultimate stopping distance is necessarily shorter with autobrakes than without.

The crew apparently stated that they started applying brakes immediately AFTER realizing they were having difficulty getting the engines in reverse. That would mean there was a delay in getting the TR's deployed AND in applying wheel brakes.

Perhaps a different interpretation of media accounts or you've seen a report that worded it differently than what I've seen. This is representative:

"Investigators say pilots told them they began braking manually as soon as they noticed the plane wasn't slowing-down properly."

Nothing about not applying manual brakes until after the problem with T/R deployment. Plus it's hard for me to believe that they would be relying on T/R for deceleration and not apply brakes till they realized there was a problem with the T/R - not at an airport like MDW in any conditions, much less the conditions that existed at the time.

In any case, use of autobrakes would not have resulted in a worse outcome, only a potentially better one. If you felt the autobrakes weren't working well, and applied brakes manually, then you would have gained whatever minimal stopping action that lose when you go completely manual and start to apply brakes at sone poin after touchdown (ie, not immediately).

Like I said before, I'll give you that under one set of conditions - the setting selected for autobrakes is extracting every last bit of braking effectiveness given the runway conditions. But, as I also said, the only way to know if that is true or not is to attempt greater breaking manually. If no extra brake effectiveness is available, nothing lost - the antiskik will still extract the maximum available as with autobrakes. But if more braking effectiveness is available, not overriding the autobrakes leaves that extra braking "on the table".

It's really a simple thing to demonstrate. In the sim, make an autoland using only autobrakes to stop the plane. Then make the same autoland to the same runway using manual brakes only. I'll guarantee you that the manual brakes will stop in less distance - except in the situation where the autobrakes are extracting all the stopping power available under the runway conditions. In that one case, the autobrakes application of braking sooner makes the difference, but only in that one case (and we'll probably never know if that was the case at MDW)

The crew, to my understanding, did NOT use autobrakes, as it would have been a violation of SOP.

If true, just more reason to expect that they didn't wait for T/R deployment (or failure to deploy) to apply brakes. The crew would have been used to braking manually - all that "corner cutting" that's been mentioned like making early turnoffs doesn't come from waiting for T/R deployment to start braking. It comes from braking as soon as the weight is on the wheels - spoiler deployment and not T/R deployment. To expect them to wait for T/R deployment at a place like MDW with the conditions that existed that night seems unreasonable.

Could you clear up something for us, since no one at SWA seems to know.... What are the conditions that are required for TR deployment on the -300. the reason I'm wondering about the 300 is that SWA may have stipulate similar settings for it's 700 to keep fleet commonality. On the 200, the ground sensing swith was on the right main gear, but I think the 200 could deploy it's TR's with either the Right main gear strut being compressed OR the nose gear strut being compressed.

It's been a long time since my -200 days. I do remember a modification that added radio altimeter less than 10 feet for 2-3 seconds as a backup to the squat switch. That came from our (Piedmont) overrun accident in CLT where hydroplaning was involved - no wheel spinup, thus no auto-spoiler deployment, thus no T/R deployment available.

As for the -300, T/R deployment is possible with squat switch in ground mode or radio altimeter less than 10 ft. The latter may have been a modification like the -200's - I wasn't on the -300 at that time.

Jim

 

[BoeingBoy]

Like I've said before, I don't know squat about the -700, but here's what the US manual says about field length required with "poor" braking action for the -300. This assumes touchdown at the 1000 ft point, maximum braking (not "Max" selected on the autobrakes), and maximum reverse thrust (and no correction is given for tailwind). There's a disclaimer that this is supplied by Boeing and is not FAA approved.

Flaps 30 landing:
110,000 lb weight - 4734 ft runway length
120,000 lb weight* - 5100 ft runway length

Flaps 40 landing:
110,000 lb weight - 4600 ft runway length
120,000 lb weight* - 4960 ft runway length

* this is above max landing weight in the -300

Jim

 

[2BorNot2B]

I have truly appreciated all the inputs on this thread .... been 10 yrs since my "Last Trip" on my beloved -400! In my 22k+ Hours I experienced many of these difficult situations and was fortunate to never have an incident. Many of the inputs here have re-kindled those memories and of course made me question what really happened!
Unfortunately much of what was/is reported by the Media is inaccurate. So there is little to go on at this point except speculation.
I am not aware of changes from the -400. Some questions arise. Media reports today say that the "the balky thrust reverser switch" may have caused a problem! Are the reversers no longer a function of the Throttle Levers?? They also say the Auto-spoilers worked normally ...think about strut switches here .. but they are not deployed in the accident photo. (may have been stowed by crew per evacuation procedure, but it appears there was no emergency evacuation ordered).
That presents another question .... photos show the only opened door was the Main Pax door ... why not the Galley door also. Other Emergency Exits were basically unuseable. A previous post stated that Pax remained on the Aircraft for 10 min before evacuating!!! Why?? The threat of fire was great ... especially with the crushed car's gasoline.

2b

 

[Phoenix]

..Call me old fashioned....

Don't get me wrong, hand flying is a hell of a lot more enjoyable than watching George.

I can't recall many accidents that an experienced pilot caused because he wasn't able to keep up with the stick and rudder part, until he failed to use his head to stay out of a situation that exceeded his ability. George is a tool that some people use to reduce work load when it seems useful. To each his own.

Some people use luggage with wheels and some are still old fashioned. Heh heh

 

[Busdrvr]

They also say the Auto-spoilers worked normally ...think about strut switches here .. but they are not deployed in the accident photo. (may have been stowed by crew per evacuation procedure, but it appears there was no emergency evacuation ordered).

I'm assuming they ran the checklist up to the point they would order the evac. Obviously they ran a checklist of some sort, or the engines would still be running.... . I have no problem with them NOT ordering the evac. they'll be MMQB'd on it surely, but with the evac, someone would surely have been hurt, and it may have caused problems with the rescue efforts below the jet.

Nothing about not applying manual brakes until after the problem with T/R deployment. Plus it's hard for me to believe that they would be relying on T/R for deceleration and not apply brakes till they realized there was a problem with the T/R - not at an airport like MDW in any conditions, much less the conditions that existed at the time.

Actually Jim, I think that's precisely they way they were doing it. Reversers, THEN wheel brakes. They may have even reasoned (falsely) that they should use TR's primarily due to the runway condition. I don't know. But, before monday, SWA did NOT authorize autobrakes to be used EXCEPT for RTO's. At least that's my understanding

It's been a long time since my -200 days. I do remember a modification that added radio altimeter less than 10 feet for 2-3 seconds as a backup to the squat switch. That came from our (Piedmont) overrun accident in CLT where hydroplaning was involved - no wheel spinup, thus no auto-spoiler deployment, thus no T/R deployment available.

My old 200 adv books say spinup for autobrakes to start working, but Squat switch on the right main for gnd spoilers. Diff companies may have slightly diff configs. I still remem an old crusty ex Braniff guy pounding in the notion that too much aileron on landing (or not enough after) could cause enough bank to prevent the squat switch from being tripped.

I guess our profession is being taken over by computer programers - if it's not automated it's can't be done by mere mortals.

Call me old fashioned....

We used to crash a whole lot more to. They showed a stat in one of my CRM classes that showed jets with old vs new versions, ie 747-200 vs 400, 737-200,300 (no glass) vs the glass version, ect. In all the cases, the accident rate for the new generation was roughly half that of the old. Having flown my first 2500 hours without glass, followed by 3000 with, i'll take glass and automation EVERY DAY!!

I disagree with your analysis.......autobrakes on every aircraft I have flown use a deceleration rate to determine how much pressure is sent to the brakes.

While true, the deceleration MEDIUM provides on the guppy would have stopped the jet with room to spare. therefore, medium would have demanded that rate, or the max rate the runway condition would allow , whichever is lower. In this case, it appears what the runway would have allowed would have been LOWER. Don't base you opinion of flight control settings on the bus. that dang thing was a violation waiting to happen. I used to get a kick out of Stand Capts who really pushed the Vnav descent tell me how it would make all the alt restrictions and would NEVER overspeed, and then proceed to attempt to do both. That dang jet was so concerned about spilling a fricken drink.... I'd always have to hold on to prepare for that massive 5 degrees of bank it would roll into..... . The guppy on the other hand would command 30 fricken degrees for a heading change of 2 degrees. . Likewise, I don't think it commanded a delay in autobrakes.

Just for clarity, doesn't the guppy have the 1, 2, 3, RTO settings? seems like the 737 had it one way and the Bus the other. I'm getting old....

 

[2BorNot2B]

I have no problem with them NOT ordering the evac. they'll be MMQB'd on it surely, but with the evac, someone would surely have been hurt, and it may have caused problems with the rescue efforts below the jet.

I cannot believe you would make such a statement!

2B

 

[WNJETFIXER]

If they said the Speed Brakes deployed on landing I would think that the Air/Ground portion was working normal.Correct me if I'm wrong, the only way that both T/R's would not deploy would be if the R/A sensed the Aircraft was above 10FT. Each T/R has different Air sense relays that work seperate from each other.

Moderators Note: Please avoid requoting a lengthy post when possible. It makes a busy topic that much harder to read. Thank you.

 

[Busdrvr]

I cannot believe you would make such a statement!

2B

Sorry, i just can't be quite so judgemental about a split second decisions after an overrun. they were sitting in the middle of a road in a snow storm. I reserve my judgement for intentional disregard for safety that is made in advance. I did notice the Capt was 59, so maybe it'll be more fodder for keeping the retirement age at 60.... (sorry, a little levity..)

If they said the Speed Brakes deployed on landing I would think that the Air/Ground portion was working normal.

The engines apparently DID go into reverse at some point, so I think it would be speculation to guess exactly when the spoilers deployed. Just thinking outloud, but wouldn't the TR's be delayed by the engines going to idle? I don't think you can slam them from a high N1 into reverse. Could a "power on" landing delay TR deployment while the engine spools to idle?

 

[WNJETFIXER]

The engines apparently DID go into reverse at some point, so I think it would be speculation to guess exactly when the spoilers deployed. Just thinking outloud, but wouldn't the TR's be delayed by the engines going to idle? I don't think you can slam them from a high N1 into reverse. Could a "power on" landing delay TR deployment while the engine spools to idle?

That's a good question, I'll get back to you on that one.
But here's another question. With RTO, do you have to wait until the engine spool to idle for T/R & speedbrake deployment?? Whould'nt that be similar to a "power on" landing?? Just a thought.

 

[Dont call me Shirley]

Reverse Thrusters Cited in Midway Crash

By ******* * ******, Associated Press Writer

4 hours ago

CHICAGO - The reverse thrusters that should have slowed a Southwest Airlines jetliner before it slid off a runway and

I gotta chime in here about reporters (and headline writers)
using "reverse thrusters" instead of "thrust reversers". The former implies a seperate power source - sort of like bow thrusters on a cruise ship or the "thrusters" that Cpt Picard uses to nudge the Enterprise our of space dock. I know, I know; if only the calling the things by the wrong name would only be the biggest goof the press makes in covering this accident!