Almost 300 flights in and out of Heathrow Airport were cancelled during the first five days as teething problems at the new Terminal 5 caused chaos. But what went wrong on that fateful first day?
Passengers at T5 have not been getting the expected prompt service
The problems appear to be due to a combination of factors.
Some were technical, involving glitches with the sophisticated new baggage set-up, which is designed to handle 12,000 bags an hour.
But other issues were more mundane. Employees arriving for work, for example, could not find their way to the staff car park.
BA has said "initial teething problems" with car parking, delays in getting staff through security screening and staff familiarisation had resulted in a backlog of baggage which meant severe delays and flight cancellations over the days that followed.
The first warning signs came as early as 0400 GMT on Thursday when passengers began to arrive, only to be confronted with the same problems as the staff in trying to find somewhere to park.
The road signs were apparently not clear outside the terminal, and people said they were given wrong directions once inside.
But that was only the start of their problems. All the check-in desks were apparently closed at 0400 GMT, leaving passengers no option other than to form a queue.
Then, when one was finally opened, the resulting rush was "chaos" according to one would-be flyer.
The first flight arrived at T5 from Hong Kong at 0442 GMT, slightly ahead of schedule, but its passengers faced a delay of about an hour to collect their bags.
The problems began to mount and by 0630 GMT a queue of about 300 people waiting to board flights had formed, another passenger said.
As the morning wore on, some passengers had to wait up to two-and-a-half hours to collect their suitcases from baggage reclaim.
An underground conveyor system had become clogged up, according to the BBC's transport correspondent Tom Symonds.
This was being blamed on staff failing to remove luggage quickly enough at the final unloading stage.
Further technical faults also meant seven flights also had to leave T5 without luggage on board.
By Thursday lunchtime the cumulative effect meant BA had to cancel 20 flights.
By early afternoon, a queue of more than 100 people whose flights had been cancelled, stood in line to try to get away on other flights or get refunds.
To make matters worse, the luggage belt in one part of the departure lounge failed.
At about 1630 GMT, all check-in at the new BA Terminal 5 was suspended because of further problems with the baggage system.
Long queues were also building up around that time at the fast-bag drop desks, where passengers leave their luggage after checking in using computer terminals.
By about 1700 GMT, BA suspended the checking in of all luggage going into the hold.
This meant passengers already at the airport had the choice of either flying with just hand luggage, getting an alternative flight or claiming a refund.
By the end of T5's first traumatic day, a total of 34 flights had been cancelled and hundreds of passengers had been left stranded, either for a flight or even for their bags.
By Saturday, BA said at least 15,000 bags were stranded at Heathrow - with one source telling the BBC that the number may have been closer to 20,000.
While the airline says it is working to clear the bag backlog, how long it will take for BA to work off the negative publicity caused by the fiasco remains to be seen.
PROBLEM AREAS AT TERMINAL 5 ON THURSDAY
1. 0400 - Both passengers and staff have trouble locating car parks
2. 0400 - Delayed opening of check-in results in long queues
3. 0442- First passengers arrive early but wait an hour for luggage
4. All morning - Clogged conveyor leads to long wait for luggage
5. 1630 - Baggage system failure; all check-in at T5 suspended
6. 1700 - After long queues form at "fast bag drop" desk, BA suspends check-in of all luggage into hold