When Planespotting Technology Fails

The Antonov AN-124 from Russia is very large, relatively rare aircraft used to haul large cargo items that would generally otherwise need to be shipped by sea. It is also fairly difficult to track since it lacks ADS-B capable transponders and operates on a charter basis. Yesterday morning I received a tipoff that there was one inbound to Stewart International Airport, and was due to arrive at around 6:30 in the evening.  I began watching the flight closely and made tentative plans to head across the river to get a few arrival shots of it.  Ultimately I determined that the information was likely a bust and I decided not to make the trip, which proved to be a wise move in the end, as though the aircraft did arrive, it was hours earlier than expected.  So lets take a look at where the tracking technology failed and why I made my decision not to go.

Above is a screenshot from FlightAware showing the supposed path of the flight.  Since this has been updated overnight, it shows what really happened, not what I was watching.  The original time that was most significant to me was the scheduled arrival time of 6:31 PM EDT.  The entire time I tracked the flight it showed up marked as "arrived" though I knew that wasn't likely and in fact it was wrong at least in the beginning.  The known erroneous information was that the flight time from Germany was listed as 5 minutes, and there was a double entry at the bottom for the same flight number on the same day arriving about a half hour hour before the reported false arrival time.  Another clue that I found that this might be a phantom flight was that every single position report was stamped as estimated.

With a little bit of suspicion in my mind, I started digging deeper. I started by searching for the flight on the 2 live flight trackers that I use, Flightradar24 and Planefinder, and found nothing other than a mention for a historical flight that had landed in Flightradar24, but which could not be played back at that point.  Next I listened to the archived recordings for the half hour block in the morning when the flight had possibly arrived and again found nothing.  I checked a few other online trackers of unknown accuracy but all of them either couldn't find the flight or said it had arrived in the morning.  At this point there was too much evidence indicating that the aircraft had already arrived, so I made the decision not to chase it which was a wise move.

Knowing that an inbound aircraft that large was likely arriving from the east, which is the more common approach path and one that is typically flown relatively close to my house, I kept my eyes and ears to the sky at around the expected time of arrival and heard or saw nothing.   Eager to confirm that I had in fact missed the arrival, I went back to Flightradar24 where the historical playback was now working and played back the flight in high speed.  I found it over Canada and followed it as it crossed Maine, New Hampshire and Vermont before turning south near Albany, NY.  It had indeed flown right over my house, but it had done so at between 1:00 and 2:00 in the afternoon, while I was still at work.  I may never know how Flightaware came up with the 9:xx am or 6:30 pm arrival times, but I did learn to watch for inconsistencies when monitoring a flight like this.