Question about flight numbers

[t1grm]

There seems to be at least two flight numbering formats in circulation. Particularly for some of the loco's. For example I regularly fly FR2905 but on some websites it's listed as FR04KM. I never see the second format in any airport or on any booking emails or documents but on some websites when searching for flight info I can only find it using the latter code. What is the second format FR04KM? Some sort of airline internal reference?

[Hotel Tango]

The second format is its ATC radio call sign. It should however read RYR04KM. You will see that on FR24 and other tracking sites. Maybe some sites use a combination of the IATA airline code together with the alphanumerics from the call sign.

[t1grm]

Thanks

FR24 list it as RYR04KM but this site uses FR04KM. They must be using a hybrid like you suggest. Double confusion!

SPOTTERS - SPecial Over The Top Email Request System

[DaveReidUK]

Not just locos - many major carriers (BA, AF, LH, for example) use alphanumeric callsigns in situations where it is considered that the timetable flight number could lead to inadvertent confusion (such as with another carrier using a similar flight number).

For example DLH3YE is currently inbound to LHR, but the passengers' tickets will say LH914 from FRA.

https://www.skybrary.aero/index.php/Call-sign_Confusion

[t1grm]

Very informative link. Thanks

[Peter47]

I know that this is thread drift, but on another issue I note that some American carriers use the flight number for the outbound and inbound flight to and from the same airport. Obviously the individual segments will be further identified but is rather confusing!

[DaveReidUK]

Can you quote some examples ?

[MathFox]

In the early days flights used to have several stops for refuelling, etc. KLM had an Amsterdam-Jakarta (then called Batavia) before WW II with several stops and it was possible to buy tickets for only part of the route.

KLM789 is a flight starting and ending in AMS with two stops in the Caribbean (SXM and CUR), allowing flights from Amsterdam to either of the islands (and a return). Another example is QF2 (LHR-DXB-SYD).

[Peter47]

Having one flight number for sequential sectors such as BA15/16 makes perfect sense, In the case of Pan Am's round the world flight PA1/2 the flight could have about ten sectors, differing by day of the week.

An example of an out and back with with the same number is AA or MQ 3378 ORD - PIT - ORD for today (17 Nov) but there are numerous examples. Look it up on flightstats.com or aa.com. Presumably it is to identify to the airline that the same aircraft does the out & back, but that's just a guess.

[Final 3 Greens]

FYI, there are two airline codes commonly used:

2 letter IATA -e.g. BA, LH

3 letter ICAO - e.g. BAW, DLH

Usually the IATA codes are used, but one can understand why easyJet often use EZY, rather than U2.

[WHBM]

Originally Posted by Peter47

I know that this is thread drift, but on another issue I note that some American carriers use the flight number for the outbound and inbound flight to and from the same airport. Obviously the individual segments will be further identified but is rather confusing!

This is becoming an increasing trend in the US, with now very large carriers where even with 4 digits, because they block groups of numbers for specific purposes, codeshares, etc, they are starting to run out of numbers. The booking system and flight plans can handle it the same as a traditional 2-sector flight, it's just the second leg happens to be returning to the same hub. In the event that the first sector is delayed and the second is being handled by a different aircraft, say there was an aircraft swap planned at the outer point, unusual but can happen, two flights with the same number in the air in the same sector are avoided by assigning at short notice a separate number for the flight plan.

It used to be that there were traditions for flight numbers, eg evens for east/southbound and odds for west/northbound, but this obviously breaks down here.

The same arises with that old US concept, the "change of gauge", which they have long done, where a single flight number is used for say London-New York-Orlando, with a transatlantic widebody, all passengers go through the formalities at New York, and then a separate standard domestic aircraft on the onward hop to Orlando. It's a connection in all but name; the old TWA for some reason was a major exponent of this, back to prop aircraft days. If the transatlantic flight is delayed, the domestic flight is sent off on time and the through pax are just treated like any other missed connection, sometimes to their considerable surprise. Both could be in the air at New York at the same time, so the second is given a reassigned flight number.

[ExXB]

In the good old days IATA had a rule on flight numbers. But that was considered anti-competitive and it was junked.

[DaveReidUK]

IATA still has lots of rules on flight numbers. For example you can't schedule the same number for two flights from the same airport on the same day.

But their remit doesn't extend to ATC callsigns.

[DaveReidUK]

Originally Posted by WHBM

It used to be that there were traditions for flight numbers, eg evens for east/southbound and odds for west/northbound, but this obviously breaks down here.

BA still upholds a similar tradition - flight numbers departing LHR are odd for longhaul flights and even for shorthaul, with the demarcation at 300. Inbound flights use the opposite convention.

One might almost think they were still two separate airlines.

[ExXB]

No all those Resolutions and Recommended Practices were removed from the books at least a decade ago. This doesn’t stop Airlines to continue to follow the old rules, but these matters are no longer discussed.

[DaveReidUK]

No, the one-departure-only rule has certainly been in SSIM at least as recently as 2011. I don't have a newer edition to hand, but I'd be surprised if it's not still there.

A lot of airline and airport computer systems would break if carriers ignored that particular provision.

[RevMan2]

LH uses the opposite convention, as in "You've got be odd to go the Germany"...

[ExXB]

The SSIM is no longer mandatory, if it ever was. Airlines can apply it, or not. Almost all do, but none are required to.

[DaveReidUK]

I don't think was ever more than a set of SARPS.

Airlines can apply it, or not. Almost all do, but none are required to.

Agreed.

But I've never seen any evidence of airlines ignoring its provisions re flight numbers, which is what we're talking about here, probably because chaos would rapidly ensue.

Imagine looking on an airport departure screen for your flight number and finding that there's a BA123 departing this morning to XXX and another BA123 this afternoon to YYY.