A320...Asymmetric Braking (QRH 2.11)

[kuwait340]

Hello...

few things i would like to know here ...

it says...in case of NORM BRK FAULT, multiply the landing distance by :

2.35 on dry runway

1.85 on wet runway

1.90 on contaminated runway

then it says...in case of G SYS LO PR, multiply the landing disatnce by :

2.50 on dry runway

2.25 on wet runway

2.75 on contaminated runway.

the first question is: in the first case...why the factor of the wet runway is higher than the dry runway ? and why the dry runway factor is the highest off all in the first case ?

the second question: in the second case : why the contminated factor is the highest off all ...unlike the first case ?

Thanks

[Thunderbug]

My FCOM has the following note:

The landing distance coefficients for wet or contaminated runways assume the use of maximum reverse thrust on all of the operative reversers.

Dry runway assumes reverse idle only. With this mind the factors you quote then seem to make sense!
T'bug

[Office Pest]

I think the explanation could be that if you look at the distances quoted for "actual landing distance config full without autobrake" you can see that the contaminated distances are alredy factored somewhat to reflect the braking action expected therefore the landing distance multiplication will be slightly less than for a dry runway. I hope that made sense.

Best regards

Office Pest

[Chrome]

Yep so does mine. Have a look at FCOM 3.02.80 kuwait340.

Furthermore standard temperatures were used demonstrating actual landing distances on dry runways. On contaminated runways actual temperatures were used to derive with those figures giving more conservative numbers.

[kuwait340]

hmmm....that makes sense .

so all this because the distances are already factored at the first place.

thanks