FlightAware Discussions

No data for flight number, only ATC callsign (TOM/BY)?

Trying to track some TUI UK (formerly Thomson) flights, but they only appear to be recorded under their filed ATC callsign, rather than the flight number.

For example – TOM5504 (STN-CFU) operated yesterday – the last recorded data under the flight number is for October 2018, but yesterday’s flight is recorded – under TOM30Y:


(It’s not an IATA vs ICAO issue, as far as I can tell: neither TOM5504 nor BY5504 return anything, only TOM30Y).

This seems to be the case for most TOM flights I’ve tried recently. Have we lost the ability to look up based on flight number rather than (presumably ADS-B transmitted) callsign?

The flight number for the 3 June flight from STN to CFU was BY5100 on TUI fly, a B737 (G-FDZR) according to FlightRadar24.

This is the result of Eurocontrol’s call sign similarity (CSS) service that causes flights in Europe to use an alternate numbering.

FlightAware has logic to attempt to match up those flights so that they appear on our site with the airline’s true flight number, however this logic works best when each of the affected airlines provide their flight number mappings to us in advance. When they do not, our heuristics attempt to match it based on other criteria. We are working to improve CSS matching for Thompson.

I can assure you it was TOM5504…

There’s a late STN-CFU on Mondays that operates as TOM5100.

I thought there might be something like that at play. There are some general rules (as I understand it) for TUI UK flights, at least – for the four digit flight numbers, the first digit corresponds to the base (roughly) and the second the day of the week; not sure about the last two digits…