C310 crash in Waco, Tx (KACT)


#1

flightaware.com/live/flight/N69677

kxxv.com/Global/story.asp?S=5795287

Wx at the time of the accident:

KACT 110051Z 14008KT 2SM BR OVC002 10/09 A3015 RMK AO2 SLP208 T01000094 $


#2

I heard about this crash while driving to work this morning. Three people were killed when the plane crashed in a field 1/2 mile from the Waco airport (KACT). The flight had originated in Natchez, MS (KHEZ).

What I find interesting is the flight track. It stays at the same lat/lon/alt from 07:03 PM to 08:59 PM. The time of arrival is reported at 06:51 PM.

I suppose the time of arrival is whatever the FAA says it is on an ‘arrival message’. But I’m curious about why the flight track data goes on and on for about another two hours. The downed plane is certainly not still on radar, is it?

Here is a link to the Associated Press report with a few more details.


#3

I think the software “assumes” the plane is still in the air until an arrival message is recieved and makes educated guesses on its current location thinking that there is simply poor radar coverage in that area.


#4

That’s a quick response, magnetoz, thanks.

Whose software? I thought FA was simply passing along the data it gets from the FAA feed. Would the FAA keep a plane at one lat/lon/alt for two hours? Surely, that would interfere with the traffic controllers’ work, especially if it were on an approach path to KACT.

I believe that FA has reported it was developing some data editing routines which I thought were meant for those situations where a flight is at 35000 ft one minute, 3500 feet the next minute, and then back again at 35000 ft the following minute. However, if FA’s software is repeating a track point every 4th minute when FAA reports nothing and is then not erasing the repeated data to gain consistency with the arrival message, I’d think this would be an ‘unintended consequence’, i.e., a FA “bug”.

Btw, radar coverage in the immediate vicinity of President Bush’s Crawford ranch will be anything but “poor”.


#5

I think the “bug” is similar to what happens with flights over Hawaii. I remember reading in a previous post that FA assumes the flight is still in progress even when radar coverage is lost within a certain time limit. The FAA radar system does not generate an anticipated radar return and will not send and radar data to FA once they lose it on radar.

You and I know that radar coverage over that part of the country is good, but FA only knows what info it gets from the FAA.


#6

You’re right, of course, that FA only knows what data it gets from the FAA.

Therefore, if a takeoff message is received, a flight is assumed to be in the air until a landing message is received. And, similarly, a flight in the air is assumed not to be in the air if there is no takeoff message. Thus you can often see westbound flights from Europe on the radar maps, but they ‘officially’ aren’t in the air yet.

Here we’re dealing with the termination of a flight track to be consistent with the arrival message’s landing time. I thought that FA routinely edited all times to remove the 6-minute ‘live’ delay. I guess I’m surprised that something didn’t happen for N69677.

It’s no big deal, certainly nothing to rant on about. Maybe Daniel or Mark will poke his typing finger into this topic and give us some words of wisdom.


#7

Good questions.
Maybe the transponder continued reporting even after the accident, but i guess that wouldn’t result in the early arrival message.

Maybe the FAA sent an arrival message based on the filed flight plan.

It would be interesting to see how FA interprets the info from this flight.


#8

Here’s the scoop on how we collected that data.

At 2006-12-11 00:38:03Z we saw a descent begin out of 6000ft to 5400ft. It continued a descent to 2100ft and then we received an arrival notification at 00:51Z. We continued to get three more position updates at 00:54Z, 00:58Z, and 01:03Z for 1800ft, 800ft, and 600ft, respectively.

We then continued to receive that 59kt/600ft position report every few minutes for a couple hours and the software opted to display it. The reason why radar facilities will do that is unknown to me. One could speculate that there may be technical or logistical reasons why the aircraft track is “frozen” but I don’t know the reality.


#9

Thanks for the “scoop”, Daniel.

I take it that some time after the last position report was received (8:59 PM CST) you received an “arrival” message from the FAA that was ‘back-timed’ to 6:51 PM CST, which is what you report in the flight history. Alternatively, you would have been receiving position reports long after the “arrival” message was received, which doesn’t make a whole lot of sense to me.

What it all comes down to is that a whole lot of mysterious data things happen in the inner workings of ATC/FAA, which we don’t understand, but which FlightAware reports because it’s in the data stream from the FAA. It’s ‘second cousin’ to the famed “Garbage In/Garbage Out”.