Braking action reports

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Bede
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Braking action reports

#1 Post by Bede » Tue Dec 01, 2015 1:09 pm

Not to piss in the hornet's nest, but I'm curious how you guys determine what constitutes good/medium/poor braking?

I ball park it by looking at the TLR. If it took me 5000' to stop on autobrake max, I look for 5000' on the TLR. If that number shows up in the medium column, I call it medium braking.

Any other methods?
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FICU
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Re: Braking action reports

#2 Post by FICU » Tue Dec 01, 2015 1:59 pm

Explain your TLR a bit better please. What medium column are you referring to?
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Re: Braking action reports

#3 Post by AuxBatOn » Tue Dec 01, 2015 3:22 pm

If the anti-skid doesn't come on with normal braking : Good
Anti-skid comes on, but deceleration is somewhat reduced to normal: medium
Anti-skid comes on but deceleration is greatly reduced: poor
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altiplano
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Re: Braking action reports

#4 Post by altiplano » Tue Dec 01, 2015 8:07 pm

Do you use autobrake max?
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Rockie
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Re: Braking action reports

#5 Post by Rockie » Wed Dec 02, 2015 4:30 am

AuxBatOn wrote:If the anti-skid doesn't come on with normal braking : Good
Anti-skid comes on, but deceleration is somewhat reduced to normal: medium
Anti-skid comes on but deceleration is greatly reduced: poor
Works for me.

The TLR comparison method cited in the previous post is fraught with way too many problems. A braking action report is a judgement call requiring judgement - not performance charts.
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Re: Braking action reports

#6 Post by Bede » Wed Dec 02, 2015 8:32 am

Rockie wrote:
AuxBatOn wrote:If the anti-skid doesn't come on with normal braking : Good
Anti-skid comes on, but deceleration is somewhat reduced to normal: medium
Anti-skid comes on but deceleration is greatly reduced: poor
Works for me.

The TLR comparison method cited in the previous post is fraught with way too many problems. A braking action report is a judgement call requiring judgement - not performance charts.
True but if you stopped in 4000' it's clearly not poor braking.
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Re: Braking action reports

#7 Post by AuxBatOn » Wed Dec 02, 2015 8:45 am

It depends on your type. For some types, 4000 feet is very long...
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Rockie
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Re: Braking action reports

#8 Post by Rockie » Wed Dec 02, 2015 8:45 am

Bede wrote:
Rockie wrote:
AuxBatOn wrote:If the anti-skid doesn't come on with normal braking : Good
Anti-skid comes on, but deceleration is somewhat reduced to normal: medium
Anti-skid comes on but deceleration is greatly reduced: poor
Works for me.

The TLR comparison method cited in the previous post is fraught with way too many problems. A braking action report is a judgement call requiring judgement - not performance charts.
True but if you stopped in 4000' it's clearly not poor braking.
It's not about distance, it's about the relative braking effectiveness for your particular airplane for the weight and conditions. 4000 feet may in fact be very poor - or very good.



Some of the problems with using the TLR comparisons to determine braking effectiveness are:

1. Max autobrake isn't a normal setting, and if you are using it there are already braking effectiveness or field length issues.

2. The landing distance tables you are likely using are already out of date, and new ones are being developed to more accurately reflect normal operation which are longer.

3. The comparison with the chart depends on you using exactly the same technique with exactly the same skill as the test pilots who developed the chart.

4. The comparison depends on you accurately determining your actual landing distance. I don't know how you do that without some marker to gauge it by to a full stop which usually doesn't exist.

5. After landing you are usually quite busy to the gate and shouldn't be pulling out landing performance charts to compare until you are stopped and all the shutdown checks are complete. That delay isn't going to help the guy landing right behind you who may need that information.
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Re: Braking action reports

#9 Post by Fanblade » Fri Dec 04, 2015 1:58 am

It's type specific. Every airplane responds differently in the same conditions.

For example an EMJ reporting poor braking on a damp runway at 10c? Type specific.

Just like turbulence reporting. Downgrade everything an EMJ reports. That airplane feels a ripple like a sledge hammer.

I have landed behind a 37 reporting crappy braking. We went aggressive because of the report and pinned everyone to the seat in front of them. Obviously it was a greasy runway the 37 didn't like but the bus was fine with.
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Re: Braking action reports

#10 Post by tbaylx » Sat Dec 05, 2015 2:01 am

The new TALPA ARC contaminated runway braking action correlation tables have some good guidelines on the subject as well.
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