Mutt,
You need to look at JAR 1000.....
1000.A No pilot or pilots, or person or persons acting on the direction or suggestion or supervision of the pilot or pilots may try, or attempt to try or make or make attempt to try to comprehend or understand any or all, in whole or in part of the herein mentioned Joint Aviation Regulations, except as authorized by the Administrator or an agent appointed by, or inspected by the Administrator.
1000.B If the pilot, or group of associated pilots becomes aware of, or realizes, or detects, or discovers or finds that he, or she, or they, are or have been beginning to understand the Joint Aviation Regulations, they must immediately, within three (3) days notify, in writing, the Administrator.
1000.C Upon receipt of the above mentioned notice of impending comprehension, the Administrator will immediately rewrite the Joint Aviation Regulations in such a manner as to eliminate any further comprehension hazards.
1000.D The Administrator may, at his or her option, require the offending pilot, or pilots, to attend remedial instruction in Joint Aviation Regulations until such time that the pilot is too confused to be capable of understanding anything.
more seriously, from memory three runway design cases are looked at,
1) lateral forces on the nose gear,
2) the vertical ground reaction on either main gear should not become zero
3) the sum of all lateral ground friction forces should be greater than zero.
1) basically makes sure that the nose gear will steer the aircraft up to Vmcg
2) makes sure the aircraft does not do a wing over
3) makes sure the aircraft does not slide off the runway
where it lies in the JAR's I don't know ...
