British Airways chief executive, Willie Walsh, refused to resign today as the chaos at Heathrow's Terminal 5 threatened to spill over into the weekend.

The turmoil could even threaten the flag-carrier's transfer of operations from Terminal 4 by the scheduled date of April 30.

But, as full details of the opening-day disaster emerge, it is becoming clear that the nation's flag-carrier must bear the brunt of the blame for the T5 debacle.

According to informed sources, a catalogue of errors led by serious problems with BA's new baggage sorting regime caused the entire system to collapse within hours.

Things went wrong yesterday almost immediately. The first baggage shift, starting at 4.30am, was delayed by a lack of staff spaces in a specially-designated car park. Baggage handlers arrived late at the terminal's staff security checkpoint after being forced to park elsewhere. By this point, the first flight from Hong Kong was arriving and BA was already playing catch-up.

According to staff who arrived late at T5 after the car park saga, only one of the airport's employee security checkpoints was operating and at one point 60 people were queuing to get through. The bottleneck, BAA's responsibility, was exacerbated by airport and airline staff who arrived early in order to "rubberneck" and look around the new terminal.

Once into the baggage sorting area, some staff were unable to log on to the computer system, which caused three flights to "cut and run" and fly off without bags - creating the first backlog of the day.

Simultaneously BA baggage teams struggled immediately with an automated system that, via handheld devices, told them which flight to unload and which flight to put bags onto. According to staff, the devices told handlers to sort bags for flights that were already cancelled. This meant they turned up to load flights that were not there while, in other parts of the sorting area, bags piled up unattended.

Without managers on the ground to allocate work, there appeared to be a communication breakdown between handlers and their supervisors in the BA control centre elsewhere in the terminal. By midday, 20 flights were cancelled as handlers frantically tried to reduce T5's inaugural baggage mountain.

Throughout early morning and afternoon, two overarching factors contributed to the delays. According to industry sources, some baggage teams were disorientated despite months of training and were late turning up at loading areas, which are spaced around the cavernous baggage area. Plus, there was a shortage of special storage bins that all bags must be put in before going onto planes - a new requirement for T5.

By 4pm, with too many bags, too few storage bins, an already clogged conveyor belt system and handling staff under severe pressure, all it took was a wave of new luggage to choke the system to a standstill. At 4pm a wave of passengers came to Terminal 5's departure hall and checked-in bags that were delivered by a lift system to the main conveyor belt area on the ground floor.

The conveyor belt system could not physically function within one hour and ground to a halt as bags jammed the entire handling network. Minutes later BA suspended all baggage check-in. It was, according to one observer, "literally a case of the baggage computers saying 'No"'.