Expert: Capt Paul - 4/20/2007

Question
QUESTION: Dear Sir,
Why is the screen height set at 35 Feet on take off?
Regards
Madhav Nair
ANSWER: It's an arbitrary reference point where the next climb segmet begins.  

The following website will offer a good explaination

http://www.lissys.demon.co.uk/pug/c10.html

cheers

---------- FOLLOW-UP ----------

QUESTION: Sir, could the arbitrary figure be based on aerodynamic considerations like ground effect, reaction time for the pilot to divert his attention from cotrolling the aircraft on the take off roll etc... just thinking aloud as to why this figure exists and why JAA allows it to be reduced to 15 Ft for a wet runway?
Regards
Madhav Nair

Answer
The full answer is lengthy.  Kindly send me an email, and I will provide all the details - pjeeves@telus.net

(I ask for this, because I have two pilots from "Aer Lingus" and "VN Air" who constantly waste my time when they get drunk and decide to post frivolous questions. [IP addresses are logged])

Cheers