Dariuszw take a look here
http://www.pprune.org/tech-log/40722...h-trimmer.html and don't confuse MMO and Mcrit.
You can also look here
Mach Crit, Mach Number Buffet, Mach Tuck, and Mach Trimmers [Archive] - PPRuNe Forums May I suggest (if it's not too late) putting a request to Santa in for Handling the big jets?