Icy Runways

[BeechBoy]

This is predominantly for the "big-iron" drivers or anyone else where runway lengths are frequently a factor.

The landing performance data on our dispatch releases is for a bare dry runway. Modifications are made for the following factors:
- flap settings
- whether ice has accumulated on the airplane (and the approach needs to be flown 15 knots faster)
- if a tailwind is present

No consideration is given to runway conditions at all. We often land on runways where braking action is poor (mu readings of 18-19). For the Beech this isn't a problem as far as stopping the airplane (our runways are at least 5000 feet long).

But what about you guys flying the heavies? How do you determine if the airplane can stop if the braking action is only fair or poor?

The only thing I've seen on the matter is some rules of thumb in my "Fly the Wing" book. This book states that for icy runways (braking action poor) add 120% to the landing roll.

I got the graphs for the Beech and, using this rule, determined that even with zero flaps and an iced up airplane I could land at our shortest runway but just barely.

Any input?

[Realms09]

I believe in the discussion following the SWA overrun at MDW they stated the flight crew was using a performance calculator program on a laptop to compute landing distance, in which expected braking action was a parameter.

[NJA_Capt]

Originally Posted by BeechBoy

How do you determine if the airplane can stop if the braking action is only fair or poor?

The AFMs contain charts for contaminated runway data. We start with dry runway numbers and adjust for wet, slush, compact snow, loose snow wet ice, with or without T/Rs. Our dispatchers have computer programs that consider the same factors.

Landing distance can quickly go from 3500' dry to 12,000' contaminated.