FlightAware Discussions

The invisible flight

Last night I tracked flight SWA1485 from California to Dallas (DAL) because my wife was onboard. Attached is a screen shot from the FA web tracking page as the flight landed. While watching the track as the flight came into the north Texas area, I also was watching my PiAware plot. The aircraft was well within range of my station but the flight never showed on the PiAware plot or on the flight listing on the right side of the screen. As a reference my station is located about 15 miles NW of DFW and 35 miles NNW of DAL.

I am obviously missing something (and confess to being a newbie). Any ideas why SWA1485 was invisible to me on PiAware?

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https://flightaware.com/live/flight/SWA1485/history/20190620/0130Z/KSAN/KDAL/tracklog

The aircraft isn’t ADS-B equipped.

It seems MLAT for some reason didn’t work for that plane in the second half of the flight.

It should still have been in the dropdown list without a position.
The only explanation is that maybe the transponder didn’t squawk using ModeS but used Mode C as a fallback?

Only Mode C would not appear in SkyView.
(you only get altitude and a squawk, so you wouldn’t know which flight it is anyway)

It’s not that mlat didn’t work, it’s that when both FAA radar data & our own mlat are available, we prefer to use positions from the FAA for use in the tracklog.

Also, we do a lot of massaging of tail number / hexid / ident / etc when correlating the raw data into a flight shown on the website. It’s possible that the raw data from the aircraft didn’t have the right ident/callsign (either missing entirely or not the one you expected) so you missed it that way.

Thanks for the input. I guess it never occurred to me that a large US carrier flying a Boeing 737 would not have ADS-B.