Errors with track log


I keep noticing errors for flights that show big altitude changes back and forth, along with speed, for flights where I know the pilot and know it didn’t happen, and changes that would be impossible anyway.
Is this a known problem? The FAQ didn’t say.



what’s the N number of the aircraft? Chances are as the flight is handed off from Radar facility to radar facility they are reading the altitude from different distances, hence the discrepancy…no your pilot isn’t spilling his coffee in his lap!


And if you could look at the flight before that, it was similar in cruise. Also as it was decending, it would, for example:

(flight was at 15,0)

And speed changed to cruising speed every time 15,0 was shown.


The altitude jumps are a known issue. When a flight is assigned a new altitude, a radar facility (sometimes nowhere near the flight) will report immediately that the flight at that altitude. We’re working on some feed processing logic to ignore them.

That tracklog you linked to appears to have some other weirdness going on in the descent, as if it was being assigned to 14000 ft.


I still keep seeing this happening. For example, here’s another:

I know for a fact that the first part of the flight was at 6K, then the remainder at 4K, yet 6K keeps showing up. Groundspeed is doing the same thing.




Like mduell said, they already know about it. What I don’t think he made clear was that the problem is with the FAA feed, not FlightAware. They are working on a filter that will ignore these jumps.

If you look around you will see that almost every flight has at least one of these altitude jumps. The time I notice it most is right after takeoff. I’m guessing that the jump occurs when the flight is cleared to a higher altitude and the controller enters that in the computer. The tracklog will show one entry at the assigned altitude, but then on the next entry it reverts to the actual altitude.


There are two things that would most likely cause this to happen:

  1. The controller entering in the new altitude in the computer before issuing the instruction or the radar just missing the mode C on a sweep of the radar by chance (substituting the soon to be assigned different alt).

  2. The aircraft climbing or descneding so rapidly the mode C can’t keep up.

The second one happens often in busy airspace. For example, aircraft departing ALB…they climb on a 320 heading away from crossing traffic going SW into EWR and BDLs going eastbound just south of ALB (RKA.SWEDE1). The faster they climb above FL200 or so (above that other traffic descending) the faster the turn on course. “Callsign, maintain FL230, upon leaving FL200, turn left heading 170 direct PWL.” You’ve never seen aircraft climb so fast. Planes give us 6000fpm through FL200 so they can get on course. The instruction is issued around 8000, so in about a minute and a half, they are through FL200 turning left on course. The mode C goes XXX and FL230 is in the computer as a hard altitude.

Some call it being fuel effecient, I call it bribery to miss traffic.

Lets not forget that some planes just don’t have an operating Mode C either by choice or becuase its broke. And sometimes radar contact is lost. Thats when the controller enters the altitude as REPORTED by the pilot, not by the radar.



Thanks, deltamike172, but none of those scenarios apply here. BTaylor explained they’re still working on a filter. Hopefully that’ll take care of the problem eventually.