Is that 90 seconds from start to impact? That would imply a vertical speed of about 20 thousand feet per minute, or 300 knots.
Not at all unrealistic when you consider they impacted at over 500 kt.
I have only flown steam gauges, but it even there it can be an issue understanding the displays as you approach vertical flight. From what I've seen in mockups, modern PFDs are optimized for ~horizontal velocity vectors and may be completely inadequate for useful guidance in vertical flight.
Has anyone here ever done a loop in the CRJ simulator to see what the display does?