Our airline just recently instituted a procedure on both 757 and 767 whereby we are required to let the APU run for 10 minutes prior to introducing a pneumatic load (pack or packs). This on an APU design that has been around for a long as some of our junior pilots. If temps are at either extreme (warm or cold), most crews are not complying (our airline will not connect “conditioned” air).
Any other carrier establish this procedure?....Background?