actually in FMB (or in QMBpro) is not possible to set a speed over 1000km/h and an altitude over 12000
or you can set only a greater speed but it doesn't remain in mission memory
that parameters (max 1000km/h/12000m) may be satisfactory for the WW2 and the Korea
but now, with the arrive of new jets, they begin to be a bit 'too limiting for users that likes to build mission
is possible to fix them at 3600 km/h/30000m?...... so if someone wants to release an SR71/U2/Mig25.........
Vega, the only limitations with the Mission Builders (mainly the Full Mission Builder, but the QMB too because it takes missions made with it and just edits them on the fly) is how are populated the comboboxes (the droppable controls).
Having extra (higher) values will allow that for you, but at the same time they will grow in size, making less easy to fit in Window in some case.
Obviously it can be done. For the while having planes with cruise speed higher than 1000km/h or trying to have an operational altitude upper 12000m is not so frequent, but I agree with you that we are getting closer to those barriers.
Sometime I will go on the subject.
Regards,
Pablo