What the codes on your boarding pass mean – and the one you never want to see

Why is there a lone “Y” idling in the corner of your boarding pass? What does “S/O” mean? Read on... - Getty

Once upon a time, they were the rectangular strips of card without which you could not catch a plane. Increasingly, they are discreet e-tickets in the digital wallet on your phone – or else, home-printed pieces of paper, with a smudgy QR code that defeats the purpose.

But whatever form the boarding pass for your next flight takes, it features a wealth of information, digits and data. Some of it is easily recognisable, or simple to decipher. However, other combinations of numbers and letters may need a little more explanation.

Which is where this article comes in. Why is there a lone “Y” idling in the corner of your boarding pass? What does “S/O” mean? And why is “SSSS” unhappy news? Read on…

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 routes, admittedly – that might be BA001, which, currently inactive, was once used for Concorde flights to New York, and was also applied to the prestigious route from London City to JFK, with a pause at Shannon in Ireland – but that’s by the by.

The main point is that the “BA” part of the above flight number – the two-character code assigned to the airline by the International Air Transport Association (IATA) – is self-explanatory. As is any flight number that starts with “AA” (American Airlines), “AF” (Air France), “LH” (Lufthansa), “AR” (Aerolineas Argentinas), “KL” (KLM) and “NZ” (Air New Zealand). But then, some airline codes are 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 “OL” is Samoa Air.

Most curious is the IATA code for easyJet – “U2”. This is not because Sir Stelios Haji-Ioannou is a obsessive fan of The Unforgettable Fire, but because, when the airline came into existence in 1995, the most obvious options were already taken: “EJ” was assigned to New England Airlines, while “EZ” belonged to Scandinavian carrier Sun-Air. There is no link to Irish stadium-rockers in the chosen code – the allocation was random.

b''

TPBRDQ

Here in 2025, where online check-in has become a familiar part of the travel process, the six-character smush that is your booking reference (to clarify, “TPBRDQ” has been made up for the purposes of this feature) no longer holds the mystery it once might have done. 

Officially, the code is known as a “Passenger Name Record”, and it is the tip of a sizeable iceberg of digital information. It identifies you as a traveller on your particular flight, and is linked to five pertinent details: your name, where you are going, and your ticket number, as well as the contact details for, and the name of, the airline/travel agent who has made the booking (if applicable). But, increasingly, the “PNR” also provides data on your age and gender, date and place of birth, passport number and credit card digits. It reveals an enormous amount about you – which is why you need it to check in remotely.

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Y

The penultimate letter of the alphabet, sitting there all by itself, is confirmation that you have a reservation for a seat in the economy-class section of the aircraft – and that you have paid the full rate for this unremarkable experience. The same applies to H, M and B.

Q

Not only are you in economy, you have bought your seat via a discounted fare which offers less scope for changes or cancellations. Moreover, you are at the bottom of the list should there be an opportunity for an upgrade. See also: K, L, N, M, S, T, U, V, W and X.

J 

You are in business. You have – or your company has – coughed up full whack for this privilege, so make sure you grab a glass of fizz and the bag of fancy peanuts. See also C.

I

You are also in the business seats – but at a discounted rate. 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 rare moment of peace and quiet, safe from the screams of fractious children. Maybe. Or maybe not. Check the small-print.

A

Yes, A as in “A-list”. You are in First. See F and P as well.

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4 (or 5, 6, 7...)

A few years ago, a single digit on a boarding pass might have been a minor reason for head-scratching. Now – in an era where hefty baggage fees mean many of us attempt to travel with hand-luggage, and the demand for space in the overhead baggage bins is high – we have become used to milling around the gate, waiting for our number to be called.

And that number refers, of course, to your boarding group. Its precise deployment varies from carrier to carrier – but, generally, the higher the figure, the longer you will have to wait before you are summoned aboard. You know the feeling. Hello at the back, Group 9.

S/O

Good news or bad news, depending on how keen you are to reach your destination without delay. “S/O” stands, simply, for “Stopover”. You are going somewhere else on the way to the destination you have in mind. Prepare for take-off and landing…. twice.

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. To spell this out exactly, those letters mean “Stopover Paid [for by] The Carrier”. 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 longer, you should be asking for some gratis accommodation. Sadly, it has to be eight hours if you are squished into an economy seat.

If you are flying to America, watch out for the following code... - Getty

SSSS

You do not want to see this. Particularly if you are flying in the USA, where that four-letter snake-like hiss declares that the Transportation Security Administration (TSA) has selected you for a session of added scrutiny. It stands for “Secondary Security Screening Selection”, and it means that Uncle Sam is concerned about you. He has some prior information that he would like to discuss further. Probably not over coffee and cake.

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