Answer to JAR ATPL Perf question please!

[Trainee pilot]

Here is the question:

In wet conditions, what extra percentage over the calculated landing distance must be available for a turbojet?

A)43%
B)92%
C)67%
D)15%

Now, I thought the answer was 15% but the answer the school has given in the feedback notes shows 92%. Any ideas?

[Snigs]

Hi Trainee,

I think that your confusion lies in the definition of Landing Distance Required (LDR). LDR is the basic calculated figure for the a/c based on performance figures. JAR Ops requires a margin of 67% on top of the LDR for jets and an additional 15% when the r/w surface is wet. This in total is 92% (1.67 x 1.15 = 1.92)

I hope this helps. http://www.pprune.org/ubb/NonCGI/confused.gif