Originally Posted by
turboshafts
If we look at the take-off rate of climb, it is not much different to
the rate of deceleration before the incident.
If any helicopter I am travelling in accelerates vertically from take-off at a rate of 0 - 100mph in 4 seconds I think I would be having a word with the PF as my 2nd top priority.
I calculated the groundspeeds simply from scaling the distances on the map and dividing by the time elapsed between radar returns. Speed before 09:54:44 approx. 152 mph; speed after 09:54:48 approx. 54 mph. I have no idea how accurate the chart produced by AIBN is but it is a pretty large scale as you can see by the houses.