Flight Numbers any logic

[X15]

After several beers we have a loud discussion in the leaving room.... Would like to know what logic is behind issuing of flight numbers. It seems like the number is just a lucky draw!
Your reply might save a frienship.
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[Approach_plate]

Tis true. The are a lucky draw, although the premium route gets the best numbers ie. BA001 = Concorde or it did.

It gets confusing when an airline gives you similar flight numbers that depart on the same day. ie MYT at CWL. They have the MYT 755 and the MYT1755 or something like that departing on the dame day from CWL.

[Animalclub]

One airline based on a Pacific Island almost on the equator as the sequence...
day of the week/direction/route.
e.g 312
Operated Wednesday
Went west
Terminated Brisbane

[gofer]

Really does depend on the company - LX used to use the old SR logic of country group / airport / sequence in day - Air France used to use the thousand blocks of 3xxx, 5xxx & 7xxx to tell you whether the fare was Red, white or blue and the xxx as sequence within day at airport from a given airport in Paris- so an airport might have had the incomming flights as 7351, 5353, 3355, 5357, 3359, 5361, 7363 for example for the 7 daily flights inward from Paris ORY, add 1 for the returns and adjust 1st figure if required for the fare basis.

Guess the best rules are your own rules. ;)

[PAXboy]

The problems vary with the age of the carrier. Those that have been operating for awhile tend to have inherited a numbering plan for a small network and have to adapt it for an expanded one. Also, when mergers/take-overs happen.

New carrier try and start simple with the leading digit indicating the destination country and then building from there. A simple one is VS to South Africa. The first route was JNB so they are 601 = Out and 602 = Back. CPT is 603+604.

Carriers also have special numbers for code shares. These ten to be in a single Thousand group, i.e. in VS anything starting with 3 is a code share (I sit to be corrected on that).

For a carrie to tidy up it's flight numbering would be a very expensive business as the amount of material and archived documentation that would have to be changed is enormous. Also, there is no point. A flight number is meaningless until you place it in the computer and then you know everything about it. To change the numbers would cause more confusion than clarity. Also, ten years later, after more rationalisation and mergers - you would have to do it again. This problem has been largely overcome by moving to four digit numbers.

So I think that you can make up with your friend by agreeing that there is no plan!

[rsoman]

It varies from airline to airline and there is generally some method in the madness

For Air India

Three digit flight nos starting with 1 were to Euope/US
Starting with 2 to Africa
3 to Far East (Japan/Thailand/Hong Kong)
4 to Singapore/Malaysia
6 for purely domestic hops
7/8/9 for the middle east sectors

Thus we find AI 101 is to LHR and JFK, AI 145 to CDG and EWR while the new LAX route which is starting next month gets AI 137.

Similary AI 201 is to NBO, AI 314 is to HKG and KIX while 472 gets you to Jakarta via SIN.

All Air India code shares have four digit numbers.

Similary for Indian domestic operator Sahara who have a 737/CRJ fleet

All the 737s have three digit flight numbers while their CRJ flight nos have four digits.

Indian Airlines who uses the aircraft of subsidiary alliance air as well, uses the same technique

All flights operated by Indian AIrlines aircraft have three digits while alliance air aircraft have four digit flight numbers starting with 7.

A classic case is the flight from Madras to Port Blair operated till recently by alliance air 737 whereby the flight no was IC 7549. Recently Indian Airlines replaced the equipment with their own A320s where by the flight number changed to IC549.

[Hartington]

I think most airlines tend to allocate specific blocks to flights they code share onto.

One well known UK based carrier started a system (and still seems to use it) that was 0-299 long haul and 300-999 short haul. Originally domestic was 4xxx but now 1xxx. Bear in mind, however, that as noted above not all flights fit into that rule where the flight is actually operated by someone else on a code share or franchise basis.

[OFBSLF]

In the past, at least one airline (Delta? American?) separated out flight numbers based on equipment. Flt 3xxx meant an MD80, 4xxx meant a 727, etc. Dunno if they still do that.

[Boss Raptor]

There is another source. In some countries with rather basic ATC equipment they will issue local carriers with a block of numbers so that in theory when they are working procedural control only one local carrier will be using a similar flight number and so less potential confusion/room for error...for example in West Africa our block allocated was XXX 710-740 (others had 709 and below or 741 upwards etc.)

However this is only for ATC use and does not tie you to using those numbers on the Computer Reservation System (carriers like BA use flight numbers which in some cases bear no resemblance to the CRS Flight no.)...in fact we couldnt tie our ATC numbers to the CRS numbers as we had more actual services than ATC numbers allocated and had to duplicate their use many times on different days or different routes.