Flight performance question

[mickypitch]

Hi hope someone can explain this?????????

In the BGS database a question asks what factor for landing distance for a T/Jet be multiplied for LDR. (question 4226)

Tjets are factor 1.67 and 60%

The factor is 1.67 but the correct answer given is 0.60
Why? as I have always factored using the 1.67

Solution would be helpful

Cheers
Mick

[pilotincommand]

Depends on how the question is worded but LDR must not exceed 0.6xLDA.

[pugzi]

The point is that the question stated "what must you multiply the LDA by". The word multiply is the key.
2000 m LDA. If you multiply this by 1.67 you get 3340. Erm, if the runway is only 2000 m, I would not suggest you land in 3340 m.
So we take the LDA 2000m and multiply it by 0.6 to get 1200. OK? You must have a mass that will allow a landing in 1200m in order to comply with the regulations.
You have probably been used to doing questions with calculations the other way round. I.e You have a landing distance of 1500m, what must your LDA be?. In this case, yeah, multiply the 1500m by 1.67 to find the appropriate length of runway.
Easy when you know how
Steve

[mickypitch]

Hi your right it seems obvious now. :\
Thanks for replying and explaining it so well.
Cheers
Mick