The reasons why some instructors want it turn to mode A only is so that they can getaway with airspace infringments and also if they bust a not above clearance. There is also issues with not having any radar evidence if some one accuses you of a rule 5 bust. If you have carlie on they will find some radar that had you on. With it off its your word against whoever reported you that you were below 600ft agl.
There is no other reason for it.
It doesn't help either that some towers tell you to turn it either off or to mode A in the circuit thus removing any safe guards for commercial traffic.
Last edited by mad_jock; 6th August 2011 at 10:03.