I have had problems on last couple of Concorde flights. I getup to 25000 ft and level off...airplane accelerates up to approx.8 mach and I get overspeed and stress crash. Is that normal fora bird that will go mach 2 at FL55?

According to my airspeed indicator, you can go as fast as 400 knots up to FL250. My system indics .80 mach is approx 325 knots. However, when I dialed up .80 mach on the autopilot, my Concorde also exceeded 400 knots and I had an overspeed indicator flash. There must be something wrong with the mach simulation. I would just use the knots and follow the barber pole on the airspeed indicator until I reached FL55. If you keep your speed behind the barber pole you won't have any speed problems. You should constantly monitor the indicator as it could flucuate up and down as you go higher and level off. I have a reference checklist I had from a previous version of Concorde which states, in part:VMO - Maximum Operating Speed (airspeed) 400 KIAS (5,000' - 32,000' MSL) 400 - 530 KIAS 32,000' - 44,000' MSL) 530 KIAS (44,000' - 50,000' MSL)MMO - Maximum Operating Speed (Mach) .65 - 1.07 Mach (5,000' - 32,000' MSL) 1.75 - 2.0 Mach (44,000' - 50,000' MSL) 2.04 Mach (51,000 - 60,000' MSL)Hope this helps.Jim