What you didn't know about your boarding pass – the mystery codes unscrambled

It is one of the fundamental facets of modern existence. That slip of paper, slice of card or - if you are being all cool and up-to-the-minute - patch of computerised pixels, downloaded onto your phone, which opens gates and doors at airports; the very literal ticket to travel without which you could not venture far - even if your plane is fully fuelled, the pilots are in the cockpit and you have more air miles than Richard Branson.

But for all this, we tend to use our boarding passes simply for soaring from A to B, before discarding them with scarcely a backward glance.

In fact, most of us never glance at them again once we have absorbed that crucial seat number and wedged ourselves into position next to the rotund gentleman and the fidgety child. We don't give much thought to the other letters and digits inscribed on the paper/card/download - even though they contain a wealth of information about us, and where we are going.

But what are these letters and digits. And what do they mean? All is revealed below...

BA2690

An obvious one. The combination of letters and digits which appears most prominently on any boarding pass is, of course, the flight number. In this case, this is the British Airways service between Gatwick and Innsbruck in Austria. Not the most eulogised of our national carrier's flights - that might be BA001, which hops from London City to New York JFK, with a quick stop at Shannon airport in Ireland - but that's by the by.

The point is that the "BA" part of the above flight number is self-explanatory. As is any flight number which begins "AA" (American Airlines), "AF" (Air France), "LH" (Lufthansa), "AR" (Aerolineas Argentinas) and "KL" (KLM). But then, some airline codes are a little less clear - such as "QF" (Qantas) and "VS" (Virgin Atlantic). And some are downright obtuse. "WB" is Rwandair, "FR" is Ryanair, "SU" is Aeroflot,  "AY" is Finnair - and "U2" is easyJet. Perhaps Stelios is a big fan of Achtung Baby.

TPB6D3

If you are at the airport and you need to identify the airline you will imminently be travelling with from your boarding pass, you probably aren't going to get very far in the first place. But the six-character smush which also adorns your permit to fly - like the one above, which is entirely made up for the purpose of this feature - needs a little more explanation.

Your boarding pass probably refers to it as your "Booking Reference". Officially, it is a "Passenger Name Record", and it is the tip of a swarthy iceberg of online information. It identifies you, specifically, on your particular flight, and is linked, firstly, to five key details - your name, where you are going, and your ticket number, as well as the contact details for, and name of, the airline/travel agent who has made the booking (if applicable). But, increasingly, it is also tied to details on your age, gender, date and place of birth, passport number and credit card digits. It is, in effect, a date stamp on your forehead - which is why you need it to check in online.

Y

You will probably be aware of this already, but a lone example of the penultimate letter of the Roman is confirmation that you have a reservation for an economy seat. And you have paid the full rate for this experience. The same applies to H, M and B.

Q

Not only are you in economy. You have - clever you - bought a discounted fare for the back of the plane. A splendid cash-saving short-cut. Of course, what it does mean is that you are at the bottom of the list should - oh wonder of wonders - there be an opportunity for an upgrade. The same applies to K, L, N, M, S, T, U, V, W and X.

J 

Hooray, you have an expense account. You are in business. See also C.

I

Hooray, you are in business - and at a discounted rate to boot. See also D.

E

You are in the sometimes vague and unspecified border world that is Premium Economy. Does that mean a free drink? An extra-reclinable seat? A chance to watch the latest Oscar-worthy movie starring Adam Sandler? Perhaps. Check the smallprint.

A

Yes, A as in "A-list". You're in First. See F and P as well, oh privileged traveller you.

4 (or 3, 2...)

This will probably be floating around all by itself too. And it isn't much of a mystery. It's your boarding group number. Airline staff use it to decide the order in which passengers are allowed to clamber onto their nice and shiny aircraft. Its precise deployment varies from carrier to carrier - but, generally, the higher the number, the longer you will have to wait before you are beckoned on board. You know the feeling.

S/O

Good news or bad news, depending on how keen you are to reach your destination fast. If you would really love to get off this particular plane and stretch your legs then - oh happy day - you have a stopover. If you just want to be home already then... ah, sorry.

SPTC

You are not just facing a stopover, but a stopover long enough that you are entitled to request a hotel room, free of charge, from your airline. Various conditions apply, of course. Your onward connection needs to be with the same airline. And the exact definition of what constitutes a long stopover varies from carrier to carrier, and depends on which cabin you are travelling in. That said, as a general rule, if you are flying in first class, and your stopover is six hours or more, you should be asking for some gratis accommodation. It's eight hours if you are squished into an economy seat.

SSSS

You do not want to see this. It is not good. Particularly if you are flying in the USA, where that four-letter snake-like sound declares that the Transportation Security Administration (TSA) has selected you for extra screening procedures. It stands for "Secondary Security Screening Selection", and it means that Uncle Sam is suspicious about you. He has some prior information he would like to discuss with you. Probably not over coffee. Perhaps in a scenario involving rubber gloves. It is not your lucky day.