What's the deal with time-varying alphanumeric callsigns?

Question

The other day a friend of mine was flying Dubai to Washington (OMDB->KIAD) and the IATA flight number was EK231. I decided to track the departure on FlightRadar24 (hereafter F24). F24 told me that the ICAO flight number (written form of the callsign) for this flight is UAE231. So when the departure time came, I set the map to OMDB and started scanning for UAE231 among the aircraft at OMDB. When I couldn't find for half an hour, I assumed that the flight was late and broke off. Thereafter, every 15-20 minutes I returned to F24 and did two things : (a) search for "UAE231" in the search flight tab, and (b) scan the ICAO flight numbers at OMDB. In no case I found UAE231.

After about three hours I decided to check the airline website and found that the flight had in fact departed on time. Returning to F24, I scanned the appropriate location of sky and found it operating with the impromptu ICAO flight number UAE3MX. F24 also possessed the information that the IATA flight number of this vehicle was EK231, so maybe a search for "EK231" instead of "UAE231" would have yielded the airplane much sooner.

My questions basically are (a) why did the flight adopt an ad hoc ICAO number on that day (and in general why a flight may do this), and (b) if this happens, how do people outside the airline (for instance F24 guys, airport passenger information providers etc) connect the callsign to the IATA flight number ? For that matter, how does ATC do it (they only see the ICAO flight number don't they) ?

Please note that my question is not about why there are alphanumeric callsigns in general or about why delayed flights use different callsigns (that day's EK231 was NOT delayed). But if a change of ICAO flight number can be made at random by the airline despatcher then I would have thought confusion gets created for everyone involved. Since I have not seen this kind of stuff in either US (hyper-busy so requires efficient organization) or India (infra-scarce and therefore again needs efficient organization), I was also wondering if this is a UAE doing differently thing.

Answer 1

I checked a few dozen EK231 flights between February this year and today on FR24; all had the flight identifier UAE3MX. It is the standard flight id that Emirates uses on this route.

I don't know how you got the info the this flight uses UAE231, because if I search FR24 for EK231, I get a list of flight with UAE3MX as flight id.

So the answer to your first question is:it didn't use an ad-hoc flight id, it used the standard id.

Answer 2

From my exprience using flightradar, this is just a display issue, I checked your flight, EK231/UAE3MX, and indeed, it does not show the 3MX callsign, the way to fix this is to simply just click into one of the replays of the flight and it'll show the UAE3MX callsign if the callsign is indeed displayed incorrect initially.