What good does it do to be afraid? It doesn't help anything. You better try and figure out what's happening and correct it.
Chuck YeagerAt 42,000' in approximately level flight, a third cylinder was turned on. Acceleration was rapid and speed increased to .98 Mach. The needle of the machmeter fluctuated at this reading momentarily, then passed off the scale. Assuming that the off-scale reading remained linear, it is estimated that 1.05 Mach was attained at this time.
Chuck Yeager