SWA overrun NTSB preliminary facts.
- Thread starter USMCmech
- Start date
flyover
New Member
Maximillian_Jenius said:
Saw some actual engineering figures on a widebody jet. The difference in stopping distance for a rejected takeoff initiated at V1 (around 160 KIAS) between using thrust reversers and not using them was around 275 to 500 feet depending on some other variables.
FlyChicaga
Vintage Restoration
On our aircraft, it is now recommended we only use reverse when the stopping capability of the aircraft is in question (not outside landing data, however), like on a contaminated runway or in gusty conditions. Otherwise we just pop the buckets and use normal braking. In some models of the Embraer we have, I'll use minimal reverse and less brakes just due to the type. Some aircraft models have a tendency to heat up quickly.
I believe at American Eagle they don't use reverse thrust (even the buckets) unless the runway landing distance is less than 6000 feet. Something like that.
Way too many variables in this SWA accident. People will try to pin it on one thing, like the reversers, but in all aviation accidents you'll find that it's a string of events that will cause a certain outcome. It could be a company SOP, combined with runway conditions, with a tailwind, with a reverser delay, with improper runway snow removal, to improper reports from ATC, and/or anything else.
I think we'll learn a lot from this accident. I've already learned from it.
I believe at American Eagle they don't use reverse thrust (even the buckets) unless the runway landing distance is less than 6000 feet. Something like that.
Way too many variables in this SWA accident. People will try to pin it on one thing, like the reversers, but in all aviation accidents you'll find that it's a string of events that will cause a certain outcome. It could be a company SOP, combined with runway conditions, with a tailwind, with a reverser delay, with improper runway snow removal, to improper reports from ATC, and/or anything else.
I think we'll learn a lot from this accident. I've already learned from it.
flyover
New Member
FlyChicaga said:
Agree that things probably added up on this one. But I expect that one thing that may come out of this is more guidance for pilots on slick runways. As an example: going from the standard 10 kts max tailwind to ZERO tailwind allowed iwith degraded braking. It makes it less of a "judgement call" which always improves safety.
FlyChicaga
Vintage Restoration
I happen to have a copy of our Quick Reference Handbook here, with Required and Actual landing distance charts.
For an RJ weighing 42000 lbs (around max gross weight), at a pressure altitude of sea level, required landing distance is 4553. A wet runway adds 15% to this distance, and a tailwind up to 10 knots adds 18% to this distance. In the MDW example, this would be 6055 feet.
4553 standard.
+819 tailwind.
+683 wet runway.
We would not be able to land at max gross weight on this runway due to the required landing distance for 31C. And we are an ERJ. We could stop due to the actual landing distance with maximum braking and a landing in the touchdown zone, so the book says...
For an RJ weighing 42000 lbs (around max gross weight), at a pressure altitude of sea level, required landing distance is 4553. A wet runway adds 15% to this distance, and a tailwind up to 10 knots adds 18% to this distance. In the MDW example, this would be 6055 feet.
4553 standard.
+819 tailwind.
+683 wet runway.
We would not be able to land at max gross weight on this runway due to the required landing distance for 31C. And we are an ERJ. We could stop due to the actual landing distance with maximum braking and a landing in the touchdown zone, so the book says...
EagleATR
New Member
Okay guys, there's a few things about MDW you have to understand. The landing runway is not necessarily based upon what the wind direction is. Instead, it's based upon what runways are in use at ORD. They don't want the MDW traffic messing things up at ORD. Also, if I remember correctly, runway 31 has the lowest approach minimums.
There are also a couple other factors at play here. The winds reported by MDW tower, in my experience, are somewhat optomistic. They know we can't land with more than a 10 knot tailwind, so the winds are always reported below that, or as light and variable no matter what the actually may be. I've made approaches into 31C in a 73-800 with the FMS showing tailwinds of greater that 25 knots all the way to the ground.
The other big factor is that all of 31C is not grooved. The first part and the last part are, but the middle is not. Also, a lot of times when it snows there, they don't plow all the runway, only the approach end. There have been times when BA was good in the beginning and poor to nil at the end.
On another subject, assuming the 700 is like the 800, both the TR's and the speed brakes can be deployed within 10 feet RA. Also, maximum manual braking is always better than maximum auto braking, at least according to Boeing.
There are also a couple other factors at play here. The winds reported by MDW tower, in my experience, are somewhat optomistic. They know we can't land with more than a 10 knot tailwind, so the winds are always reported below that, or as light and variable no matter what the actually may be. I've made approaches into 31C in a 73-800 with the FMS showing tailwinds of greater that 25 knots all the way to the ground.
The other big factor is that all of 31C is not grooved. The first part and the last part are, but the middle is not. Also, a lot of times when it snows there, they don't plow all the runway, only the approach end. There have been times when BA was good in the beginning and poor to nil at the end.
On another subject, assuming the 700 is like the 800, both the TR's and the speed brakes can be deployed within 10 feet RA. Also, maximum manual braking is always better than maximum auto braking, at least according to Boeing.
flyover
New Member
EagleATR said:
Agree with most everything. I've also suspected a tendency for MDW tower to fudge the winds. But I'd bet they'd deny it vociferously. So we always monitored actual winds on the FMS in a tailwind situation. So why did you land with a 25 kt. tailwind displayed on short final? I've never seen that much disparity (not that I was always looking) between reported and displayed winds once we got inside the airport boundary.
You may be right on max braking. I was probably thinking of RTO braking. No doubt they were pushing as hard as they could on the brakes but surface friction was deciding how fast they stopped.
Maximilian_Jenius
Super User
EagleATR said:
Amtran?
-Matthew
EagleATR
New Member
We landeda t MDW with the FMS showing that much of a tailwind because we were pretty light, and the other choice was to divert. We had asked for 13C, but, of course, they wouldn't give it to us because of the ORD traffic pattern. You learn to deal with it and duck below the GS on short final.
And, yes, I was at ATA until I got furloughed.
And, yes, I was at ATA until I got furloughed.
Maximilian_Jenius
Super User
...sorry to hear bout the furlough hopefully your on to bigger and better things in your aviation career!
-Matthew
-Matthew
FlyChicaga
Vintage Restoration
How much of a delay in sensing does the B738 FMS have in the wind vector display? I know ours is a minute or more. Takes only two minutes to get from 2000 feet to the runway on the approach, therefore at least in our aircraft the FMS reported winds are not extremely accurate for touchdown winds. Plus, winds at 300 feet AGL (especially at MDW with the fenceline) are often much different than at the surface. I've noticed normally around 300-600 feet is where you get a slight "shear" with surface and winds for the approach.
We didn't have the luxury of an FMS wind vector in the Saab at MDW, so we just went by ATC.
I've never landed there with more than a 10 knot reported tailwind. I have experienced many times a large variation in the surface wind there though, like the time we had a 30 knot loss in the flare with winds from 250 @ 35 landing 31C. MDW is certainly a different breed of animal, that's for sure.
If the winds were from an easterly heading, I'm not sure why they weren't just landing 4R. Even though the DA is 100+ feet higher, it would have made a great benefit for landing distance in this case.
We didn't have the luxury of an FMS wind vector in the Saab at MDW, so we just went by ATC.
I've never landed there with more than a 10 knot reported tailwind. I have experienced many times a large variation in the surface wind there though, like the time we had a 30 knot loss in the flare with winds from 250 @ 35 landing 31C. MDW is certainly a different breed of animal, that's for sure.If the winds were from an easterly heading, I'm not sure why they weren't just landing 4R. Even though the DA is 100+ feet higher, it would have made a great benefit for landing distance in this case.
I don't know if it even has much of a delay in the -88, the usually seemed fairly consistent with what ATC was saying unless there was an ulterior motive.
Best bet I've learned? The windsock. But I wish the FAA would do a better job with regulations about them being available, discernable and well-lit.
Best bet I've learned? The windsock. But I wish the FAA would do a better job with regulations about them being available, discernable and well-lit.
FlyChicaga
Vintage Restoration
Doug Taylor said:
Seriously! There are many airports where I'll get down to around 200 feet and start looking for the windsock, and can't find one. I always use it to determine how to flare and adjust for a crosswind. Irks me when it's not there... really, how much does it cost? For a piece of orange fabric, a pole, and a lightbulb?