While on the subject of 727’s, can somebody please tell me why the VMO (IAS) actually INCREASES with altitude in both Mode A and Mode B?? I just find it interesting given the other jets I have flown have a constant VMO figure until Mach crossover around the high 20’s and then the IAS obviously decreases at the same Mach. Given how loud the 737 flight deck is at 320kts one can only imagine the noise at over 400kts in Mode A. Would have loved to have flown the three holer- great looking jet. Cheers