Grade: A+
Here's an extreme example:
I used to do functional check flights on F-4 Phantoms. I've been at FL500, indicating 230 knots,
and the Mach was 1.10.
Which would mean for your 1900, with a Mach-crit of 0.48, your limiting IAS would be about 110 kts (if you could get a 1900 to FL500)