Analysis of OpenATC ADS-B Data
Warning: I realise the OpenATC ADS-B reported data is entirely unqualified so the following analysis must be read in this context.
The above flight data is presented at equal data point time intervals. By taking the recorded Latt/Long positions I have calculated the distance travelled between successive data points along the flight track. From this it is then possible to calculate the aircraft groundspeed for each 15 second time interval.
Unfortunately, I don't know how to insert the graphs into this post so a description of how would be appreciated!
Unitl then, I can describe that the graphs show the calculated speed tracking an average of 65 kts slower than the reported ground speed and reaching a minimum value of 130 kts calculated (203 kts reported) at 9 nm before the accident site then increasing to 183 kts calculated (191 kts reported) at 6 nm before the accident where the calculated speed then matches almost exactly the reported speed from then all the way to the accident site.
Simply taking the Starting & Accident Point data yields a track distance travelled of 26.66 nm in a time of 585 seconds (9 mins 45 secs) giving a calculated average aircraft ground speed of 158 kts which seems rather slow to me?
IF the reported Latt/Long points and time stamps are correct (a very, very big IF) then this would suggest the aircraft ground speed was considerably slower than would normally be expected and would suggest something else untoward was happening way before localiser and subsequent glide slope intercepts.
Let me know how and I'd be pleased to publish the graphs.
PPL&Eng
Last edited by PPL&Engineer; 10th Mar 2009 at 08:13.
Reason: Spelling Mistake