What happens when your flight is standing-room only?

After 20 years working in the travel industry, I have heard about some bizarre flight experiences. The most outrageous almost always seem to concern flights on airlines based in developing countries: very few take place on flights operated by European, North American or antipodean carriers. But what follows did not take place on an ancient bullet-riddled plane in a banana republic. In fact, the story begins just across the Irish Sea.

The airport is Dublin and the airline is BMI (as the UK's second-largest full-service carrier, formerly called British Midland, is now known).

When passengers, including Andre Ayache, tried to check in for flight BD130 from Dublin to London Heathrow, they discovered the computers were down. Such problems are far from unknown – when it happens, contingency plans come into effect.

Boarding passes are written out by hand, names are ticked off on the passenger list, and travellers are warned that there will be no pre-allocation of seating.

Mr Ayache was booked in business class, which entitled him to relax before the flight in the executive lounge. But to make sure he could choose his seat on board, he decided to waive his right to free food and drink to make sure he was at the front of the queue at the departure gate.

The boarding procedure seemed relatively smooth. Mr Ayache found himself a seat and buried himself in working through the notes of his business meeting.

Despite his concentration, he became dimly aware of a commotion in the main cabin behind him. It was not until the captain's voice came over the public address system that the exact nature of the problem became clear.

All the seats on the plane were full. In addition, there were no fewer than 33 passengers standing in the aisle of the main cabin. It seems that though check-in staff had coped admirably with the manual check-in procedures, they had fared less well with that other long-forgotten practice of adding up. Standing passengers might be the norm on terrestrial buses but are a no-no on Airbuses. Phil Shepherd, a spokesman for BMI, says: "On this occasion it appears there was an error made during the check-in process, resulting in too many passengers being allowed to board the aircraft."

The airline's initial response to the problem of the surplus passengers was to approach those giving a new twist to the term "standby". They were offered a seat on the next flight (due to depart a couple of hours later) plus a choice of financial sweetener: €100 (£65) in cash or €500 (£325) in the form of travel vouchers for future trips on BMI. (This is known as Denied Boarding Compensation but I'm not sure that the term is appropriate in this case as these passengers had been encouraged to board).

About 20 passengers took advantage of these offers but that still left a baker's dozen who didn't. So the business-class passengers (each of whom had paid between £270 and £320 for their return tickets) were asked to go and stand in the main cabin: they were assured that this was just a temporary measure and that they wouldn't lose their original seats. The captain also announced that their compliance would mean a better chance of the flight actually departing.

The plan that the cabin crew had hatched was to take advantage of a design feature on BMI aircraft that allows two-abreast seats to be magically expanded to a threesome. Flight attendants released and pulled a couple of levers and slid the seats on their rails to enlarge the middle seats and to squeeze the aisle and window ones by a few precious inches. The levers were then locked back in position. The whole operation only took a minute or two per row. The harder and longer part was to shuffle people out and back to their seats.

The flight finally departed more than two hours late. The business-class product offered by BMI ("the ultimate in comfort, convenience and service") looks impressive on paper, or online: "separate business cabin... wider and more comfortable seating... a selection of hot or cold meals". The final straw was that, once airborne, it became predictably apparent that there were not enough meals for each of the unexpectedly high number of passengers who were now on board. Mr Shepherd of BMI says, "Cabin crew used their initiative to accommodate them and minimise further delay to the flight. Unfortunately, by accommodating the needs of one group of passengers, another was inconvenienced, however we believe the cabin crew chose the best option in a difficult situation."