Alert! CNN says...

derg

derg

Apparently a "terse" writer
Staff member
Pilots are supposed to stop calculating landing distances based on thrust reverser usage.

I guess I'll find that, uhh, chart and uhh, disregard the, uhhh, thrust reverser column.

Or something.
 
It was hard to make sense of that news headline until you read what is in the report:

The pilots had used a laptop computer to calculate how far the plane needed to go to land, the NTSB said. When the runway's condition was entered as "wet-poor," the computer calculated they would be able to stop with 30 feet to spare.

But the calculations took into consideration that engine thrust reversers would be deployed at touchdown. Instead, the NTSB said, "flight data recorder information revealed that the thrust reversers were not deployed until 18 seconds after touchdown, at which point there was only about 1,000 feet of usable runway remaining."

Without the thrust reversers, the calculation would have shown a safe landing was not possible, it said.
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This is new and strange stuff to most of us I suspect. If it's true that they could only produce numbers that allowed them to stop with reversers, then that's unsafe (d'uh) and needs to be discontinued as a practice. Shouldn't impact the rest of the industry.
 
When, in the history of professional aviation, has anyone seen a landing performance chart with a calculation for thrust reversers?
 
:yeahthat:

Here's a link to the NTSB recommendation letter which explains further: http://www.ntsb.gov/recs/letters/2006/a06_16.pdf

Here's another pertinent paragraph from that letter:
The Federal Aviation Administration (FAA) does not allow the use of the reverse thrust credit when determining dispatch landing distances. Further, the decrease in stopping distance resulting from thrust reverser use (which increases the safety margin) had typically been used to offset other variables that could significantly degrade stopping performance. However, the FAA allows the reverse thrust credit to be used in calculating en route operational landing distances for some transport-category airplanes, such as the accident airplane, a 737-700. Accordingly, when using the reverse thrust credit for contaminated runways, the required runway length for 737-700 model airplanes is about 1,000 feet less than the required runway length without the reverse thrust credit. The OPCs of Southwest Airlines’ 737-300 and -500 model airplanes do not use the reverse thrust credit; therefore, these model airplanes have a greater landing safety margin. In this accident, when the thrust reversers were not (or could not be) used in a timely manner, the airplane could not be stopped on the runway because of the absence of this extra safety margin.
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(emphasis added)
 
Doug Taylor said:
When, in the history of professional aviation, has anyone seen a landing performance chart with a calculation for thrust reversers?
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Doug,

I think our contaminated charts required thrust reversers. Dry charts don't. Check it out.
 
Likewise over here. If we are working off of contaminated runways then TRs are included in the stop distance (as well as the balanced field length). If the runway is clean that TRs are not included in that number.
 
That is correct, reverse is used for landing calcs under that scenario. As far as the laptop goes, it is similar to the one FedEx uses. In fact, that's where SWA got the concept from. It is actually a lot better than what dispatch gives you for several reasons. First, most airlines only give you the max landing weight for the runway, while the laptop outputs the actual stopping distance at various braking forces. Second, it can be updated with real time data, such as that last minute update of winds from the tower (obviously there is a limit to how close to the runway you could reasonably be to accomplish this in a two pilot aircraft). While you could certainly call your dispatcher and give them the same data, in reality, there is just not time to actually do that in most cases, where we could have the new data in about 20 seconds or so if you're set up for it.
 
Doug Taylor said:
When, in the history of professional aviation, has anyone seen a landing performance chart with a calculation for thrust reversers?
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I have SWA's FOM and FRM on another computer at home. I can look up details on their landing performance calculations if you can wait the weekend.
 
I stand corrected!

Well, actually, I'm upstairs on the sofa, "I sit corrected!"

Indian-style even.
 
Doug Taylor said:
My paternal grandmother is Blackfoot!
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Oh, here comes the "I know a Native American, so I can't be racist" quickly followed up by, "Well, by know, I mean walked by... and by Native American, I meant barber shop"

Great Doug. You're exactly why this country is so hated throughout the world. (:sarcasm:)
 
Is it that you hate the webmaster or that you just hate America? :)
 
Chris_Ford said:
I, like TonyW, hate America. But for completely different reasons, of course :D
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Why do you hate America, Chris?:sarcasm:

Oh my freaking God, it is so fun to be able to say that to someone else!:rawk:
 
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