Unusual ground speeds in tracklog of Cirrus fatal accident


#1

While researching the Cirrus SR22 fatal accident at Arbor Vitae, WI, the tracklog has some odd ground speeds:


00:04 	45.75 	-89.73 	163 	5500 descending  	 Minneapolis Center
00:05 	45.80 	-89.73 	163 	5100 descending 	Minneapolis Center
00:06 	45.85 	-89.74 	169 	4300 descending 	Minneapolis Center
00:07 	45.81 	-89.75 	 24 	3900 descending 	Minneapolis Center
00:08 	45.79 	-89.71 	 56 	3300 descending 	Minneapolis Center
00:09 	45.82 	-89.72 	 42 	3200 descending 	Minneapolis Center
00:10 	45.86 	-89.73 	 78 	3200 level 	Minneapolis Center
00:11 	45.89 	-89.73 	108 	2600 descending 	Minneapolis Center
00:12 	45.92 	-89.74 	108 	2100 descending 	Minneapolis Center
00:13 	45.95 	-89.74 	108 	2100 level 	Minneapolis Center

Any explanations for why ground speed would change from 169 to 24 to 56 to 42 to 78 to 108 over a 5 minute period? Vso for an SR22 is 59 knots, so something seems pretty odd.

Cheers
Rick


#2

There has to be some false numbers. There is not way a SR22 can go 24 knots and not be in the ground.


#3

I think the key here is *ground *speed. I don’t know what the winds were but it is possible that the ground speed was 24 knots if there was a strong enough wind.


#4

Yes, but the 24 was a 169 a minute earlier. Seems highly unlikely.


#5

Ground speeds as seen by ATC radar can be off by quite a bit when an aircraft is turning, especially at lower levels where the airspeed is lower as in a landing or holding pattern. Does this correspond with the turns he made south of ARV?

John


#6

Very well thought out John…

I have seen this on procedure turns where Flight Aware will update over the final approach fix (FAF) and after the course reversal, the next update will be just before or after the FAF yielding an extraordinary low ground speed time.

Don’t know if this applies to this flight, but what you say above I would suspect is the most plausible explanation.

I seriously doubt that one will find a 145 knot change in windspeed between 3000 and 4000 feet MSL


#7

I agree.

On another note, HOLY CRAP. It is hard to recognize damiross with the new avatar/picture whatever its called.


#8

Yeah, I miss Marvin already… :cry:


#9

I miss him but I thought it was time to recognize a great airline.


#10

Dibs on Western :slight_smile:

And to commemorate post #702: Click It 8)