Travellers urged to check 1 number on tickets that could mean missed flights

As millions of Brits prepare to jet off on their summer holidays, travellers are being warned about a small but potentially critical detail on their boarding passes that could determine whether they make it onto the plane or are left stranded at the gate.

Experts have issued an alert to passengers to pay close attention to the "SEQ" number printed on their tickets. While often overlooked, this sequence number indicates the order in which a traveller checked in for their flight, and it could be the deciding factor in whether you're denied boarding on an overbooked flight.

Hadleigh Diamond, luxury airport chauffeur provider at SCS Chauffeurssaid: "SEQ stands for Sequence Number, and it tells airlines the order in which you checked in for your flight.

"A SEQ of 001 means you were the first to check in; 152 means you were the 152nd.

"While it doesn't affect your seat assignment or boarding group, it's crucial during overbooked flights, especially on budget airlines."

Airlines overbook based on the assumption that not every ticketed passenger will show up. But when everyone does turn up, as is becoming more common with surging demand, they need a fair system to determine who gets bumped.

According to Diamond, many carriers use the SEQ number as one of the key factors in deciding which passengers are involuntarily denied boarding.

Recent data from the UK Civil Aviation Authority revealed that more than six million passengers globally were denied boarding over the past year due to overbooked flights.

Many of those affected had no idea that checking in early might have protected their seat.

Passengers who check in late, travel alone, carry no checked luggage, or have paid the lowest available fare are all statistically more likely to be bumped, and the SEQ number reflects some of those variables in real time.

Diamond explained that his firm often advises clients to check in as soon as online check-in opens, usually 24 to 48 hours before departure, to secure a lower SEQ number.

Even though passengers may assume that having a confirmed seat guarantees their place on the aircraft, airlines retain the right to offload ticketed travellers in cases of overbooking, regardless of class or seat assignment.

For groups travelling together, it's particularly important that all members check in at the same time.

Diamond warned that if one person checks in late and receives a much higher SEQ number, they could be denied boarding while others are allowed to fly, potentially splitting up families or friends just minutes before departure.

"Don't assume your ticket alone is enough," Diamond added.

"If you wait until the last minute to check in, you could find yourself bumped, even if everything else is in order.

"It's a detail most people miss, but in today's travel climate, it could be the most important number on your ticket."