OT - Southwest crash

[Guest AJ]

In the interest of spawning interesting discussion, I thought I would bring this up. Below is a link to an article regarding the pilot's use of the autobrake system during the crash. Southwest Airlines forbids the use of the system.http://www.suntimes.com/output/news/cst-nws-midway14.htmlTo me it sounds unlikely that this contributed to the incident, even if it was a violation of the airline's policy. I am interested in what the rest of you think. Also why would an airline establish a policy of forbidding the the of autobrakes? Does this make any sense to those of you who are RW airline pilots?Andrew

[Guest morvious]

It is their policy to not use the brakes above 80 kts to have a quicker turn around time??But I am always told that with wet runway conditions, it is crucial to use the auto brake system, even on smaller planes like the 737.I also read in a newspaper that the thrust reverse didn't work on the plane. That would help a lot to slow down when the tires are slipping over snow and ice!-------------------------------------------CX119----------------------------------------------------------Stefan van Hierden>|

[windycloud 30]

Interesting article.Well SouthWest also prohibits the use of autothrottle and VNAV in there 737s. Their prohibition however doesn't change the fact that all these technologies including autobrake is FAA & industry aproved save technologies. Airline procedures shouldn't affect the safety of equipment functions, however pilot control can. I am not a real world airline pilot, but as far as my impression goes, the worse runway condition is due to weather the lower the autobrake setting should be. Obviously the pilot did the oposit. I also heard saying that the reversers didn't work in that accident. And now the article said the pilot didn't optimize landing speed and touchdown spot for the weather. It sounds so far it's going to be a pilot error case. And southwest should take the position of blaming the pilot for violating airline operation regulations to get itself out of this as much as possible.

[Guest neeraj.pendse]

Pilot is the scapegoat! Pilot is the scapegoat! :-bang Not an airline pilot either, but my thought also was that the time to use LESS THAN MAX on autobrake was when runway conditions are bad. Would love to see an article with more complete data on this accident ... seems there's different people saying different things.- Neeraj

[Guest WesFlight]

Southest does prohibit the autobrake system. However, no aircraft needs an autobrake system. The autobrake is one of those systems that keeps us safe. All it basically does is add another safety measure. As far as the 737 sliding off the end of the runway. Ultimately the causes are going to be wheather, ice, thrust reverser malfunction, and the lack of safety backups related to the runway. All new airports are required to have breakable concrete or concrete that colapses under the weight of the plain if it goes past the runway threshold. This airport did not have features designed to stop a plain.Also, let us not forget about the weather, there was over 7 inches of snow dropped in just a few hours. For those of you who live in areas that are used to snow know that that is incredible. Very dangerous for walking, driving, let alone landing an airplane doing close to 170 KIAS. Whether or not the auto brake was used, in my opinion does not matter. If it was used it would have only helped the plain and not posibly done any harm to it. The NTSB has said that the main malfunction is the reverse thrusters. Without reverse thrusters on a short runway like the one involved is only a death situation waiting to happen.Also, I think it is interesting to point out that the aircraft did not go that far from the runway. It stoped once it hit a light pole. Clearly it was not moving that fast. So, if this is truly the case, then autobrakes and thruster may have malfunctioned, but may not be the issue. This is why this investigation could take up to a year to complete.

[Guest Robin.B]

>Southest does prohibit the autobrake system. However, no>aircraft needs an autobrake system. The autobrake is one of>those systems that keeps us safe. All it basically does is add>another safety measure. As far as the 737 sliding off the end>of the runway. Ultimately the causes are going to be wheather,>ice, thrust reverser malfunction, and the lack of safety>backups related to the runway. All new airports are required>to have breakable concrete or concrete that colapses under the>weight of the plain if it goes past the runway threshold. This>airport did not have features designed to stop a plain.>>Also, let us not forget about the weather, there was over 7>inches of snow dropped in just a few hours. For those of you>who live in areas that are used to snow know that that is>incredible. Very dangerous for walking, driving, let alone>landing an airplane doing close to 170 KIAS. >>Whether or not the auto brake was used, in my opinion does not>matter. If it was used it would have only helped the plain and>not posibly done any harm to it. The NTSB has said that the>main malfunction is the reverse thrusters. Without reverse>thrusters on a short runway like the one involved is only a>death situation waiting to happen.>>Also, I think it is interesting to point out that the aircraft>did not go that far from the runway. It stoped once it hit a>light pole. Clearly it was not moving that fast. So, if this>is truly the case, then autobrakes and thruster may have>malfunctioned, but may not be the issue. This is why this>investigation could take up to a year to complete. Fair points!Though since when does a 737-700 land a 170KIAS? :(

[Guest afluhart]

The point I thought was kinda funny was the non-pilot tech. expert comment that he should have been using the HUD... because thats ALL he needs! Screw the ILS in low-vis... I need a HUD!

[windycloud 30]

Well Non-pilot tech comments are not worthless. I bet not all Boeing engineers are commercial pilots at the same time. We can all open a book and say ok FAA says these equipments are surficient for a zero-zero instrument approach, and this runway is long enough. But in a real life condition like that pilots really need as much assistance as can be available to them...may it be a HUD, a runway overrun, etc. So I guess the point of the comment is only that a HUD can make it more possible to make an earlier and slower touchdown in bad weather.As long as the pilot is capable and comfortable using the equipments they are supposed to make the job less risky. After all, what is all the training for.

[Guest WesFlight]

"Though since when does a 737-700 land a 170KIAS? "Yes, I'll give it to you, youre right.

[Guest WesFlight]

You are perfectly correct. The more equipment, the better and safer. Airlines could take care of the problem if they installed arrestor hooks and wires on the runway. It would give your passeners a run for their money, but it would most certaintly stop all aircraft from overrunning the runway. :-lol

[Guest tmetzinger]

A couple of points from my perspective:I'm a real life pilot, and I fly both privately and for a commercial operator, and am familiar with the "customizations" an operator places on operating procedures.I am not (yet) type rated on the 737, but am pursuing such a rating and one of my target airlines is Southwest. Because of this, I work very hard to get the latest "gouge" on procedures from real Southwest pilots. So I have access to "inside" information, like a copy of the SWA policies and procedures.Now, with the "I kinda know what I'm talking about" stuff out of the way, my points are:1. Most of what you will read in a newspaper article is, even with the best of intentions, incorrect. (i.e. the 170 knot touchdown speed). It won't be until the NTSB finishes it's inquiry that we'll really have a large number of undisputed facts to base opinions on (not that that does or even should stop speculation).2. The autobrakes don't do anything other than apply the selected braking pressure when the appropriate conditions are met, including sensors that detect adequate weight on the main gear and wheel spin up. It is easy to generate maximum brake pressure in a 737 with just your two little feet, and I'm quite sure that both pilots were braking.3. Commercial airlines are prohibited from landing at an airport when the reported braking action is "poor" or "nil". The last "official" report was that the braking action was "good", as measured by the airport authority using calibrated tools to determine it, at least 20 minutes prior to landing4. The weather was really poor, and it's not unreasonable to wonder what braking action ACTUALLY was on that runway when SWA committed to landing. There were allegedly reports of "fair" to "poor" from other aircraft, but we cannot be sure that the SWA pilots knew of this.5. Nearly all the systems for slowing the airplane (reversers, spoilers, and autobrakes) rely on logic that require the airplane to be "convinced" that it is firmly on the ground (as mentioned in point 2) before they can be used to their full effect. 6. Nearly every accident in the airline world is composed of a chain of events, and I'm sure that the NTSB will find several "if only" points where a different decision or event would have altered the outcome.7. SWA disables many "advanced" systems on their airplanes, because they feel that an involved pilot is more efficient than a pilot who is acting as a systems manager and monitor. They also maximize commonality in their fleet, which saves a significant amount of money in crew training costs.8. SWA is very much in favor of using technology, such as HUD, when it is shown that it has a significant positive impact on their operations.OK, with those points out of the way, I will now speculate on the accident.I believe that the accident is a result of many factors:Weather - the runway became snow contaminated quickly and braking action was poorer than expected. The tailwind is an additional hassle, but it's not a simple matter to change the runways - the runways facing into the wind are almost never used for arrivals because of conflicts with O'Hare operations.Systems - because of the snow contamination, I believe that the systems like the reversers and spoilers were slow to deploy, perhaps because the runway conditions prevented the various sensors from indicating that the airplane was firmly on the ground.Airport factors - the lack of suitable overrun, the "staleness" of the runway braking report, both can be contributing factors to the incident and it's fatal results.Pilots - Decision Making - depending on what the pilots knew about the condition of the runways, and any pressures on them to make this landing, and the fact that previous similar aircraft had completed the approach, the decision to approach and land rather than divert may be questionable. It will be a while before we know enough to judge this. It is fair to say that many airmen allow their judgement to be influenced by the crew just before them, and sometimes (usually with thunderstorms or winter weather) this leads to suboptimal results.I see nothing to indicate any gross negligence on anybody's part, this is more of a situation where the factors just barely stacked up against a successful outcome.Best wishes

[Guest capntom]

I used to fly 737's in and out of Midway on a fairly regular basis, (over 10 years ago). I have not flown the NG 737's, but most every variation of the 737 through the 400. The runways at Midway are fairly short by most standards, but well within the capabilities of the plane (I have turned off at mid field).Precision is required as far as being on profile and speed here and ATC is often not concerned with your needs! I have not seen much information on this accident as yet so will not comment extensively.However, excess speed can lead to long touchdown, eating up a lot of (limited) runway. Autobrakes can significantly reduce rollout distance, as in my experience, a pilot will tend to take some time (read distance) to find the appropriate application and modulation. Autobrakes, along with revese thrust (applied early) make for reduced brake wear, cooler brake temperatures and more even control, especially on slick surfaces. In the 737 there have been instances of lack of autobrake application due to lack of tire spoolup on soft landings on slick surfaces. My recollection is on older 737's this also caused a lack of reverse availabiliity, this was fixed in the 300-400 series when revesers were activated at 5' RA.Required for all weather operation here, being on speed, appropriate flap setting (40 deg) appropriate autobrake setting (at least a med value) touchdown firmly in the early touchdown zone, on speed, and use of full reverse, modulated as necessary for decelleration and directional control, monitoring of autobrake decelleration and reversion to additional manual braking or selection of a higher autobrake setting if necessary. The [plane has a lot of capability,s ometimes it is all required.Any dithering eats up runway fast, leaving one in a position where you can neither go or stop!I write this in Chicago, at O'Hare, it is snowing.Tom

[windycloud 30]

Great comments. Just curious what do you fly now?Jason

[Guest capntom]

747-400UFTom

[Guest tmetzinger]

According to my 737 manual (now that I'm home), the air/ground logic on the NG is fed by six sensors, two on each gear. Reverser levers are unlocked below 10' Radio Altitude or when in "ground" mode. Autobrakes are active when in "ground" mode and after wheel spin-up is detected. Speed Brakes can only be armed or moved to the "flight" position (not fully deployed) until the airplane is in "ground" mode (two main wheels spun up) and right main landing gear shock strut compressed, where they will normally extend fully when armed.So while reversers would likely be available, contaminated runways could prevent other systems from working as quickly as desired.But (and Tom made a great point here), a short runway like Midway really narrows the available time to evaluate the situation and react effectively. The margin for error's smaller on a good day at Midway, and the conditions at the time may have reduced it to the point where everything had to go exactly right for a happy outcome.So, while I agree with Tom that autobrakes can be more consistently effective than manual braking (certainly on my sim flights so far the autobrake has produced much smoother and shorter stops than my feet), I don't think it's possible to say "Oh, if only SWA had allowed the use of autobrakes this wouldn't have happened", and I don't think there's anything grossly wrong with SWA's philosophy.I'm looking forward to the NTSB reports on this - like most high-profile accidents, it's sparked a lot of good discussions and I think caused lots of pilots to re-evaluate their habits.Best wishes,