Tracking discrepancies

We recently had an IFR flight, landing at a towered airport, with the flight tracker showing that the flight arrived at 18:36. However, when you go to the flight log, it’s still showing the aircraft in the air at 18:39. IFR was not cancelled prior to landing. Why?

It really helps if you give a flight id and not just say “an IFR flight.”

This seems to be the norm- see Comair 20 JFK-CVG. The activity log shows it arrived at 1:30pm EST. The flight tracker shows last position report of 1:37pm EST. I checked several other flights and all showed this 5-7 min delay. I would conjecture that perhaps the radar track plots from FAA are not time stamped, but FA stamps them when they arrive during processing (hence the 6 minute delay). The departure /arrival messages would be timestamped (or at least contain time as part of the message).

Pure guess- I suspect there are a couple of folks here who can give a more definative answer.

The arrival notifications that we receive are time-stamped, but they also include an arrival time that I believe is manually entered by the tower controller. Our software generally accepts the supplied time over the timestamp and sometimes it’s a few minutes off in either direction.