Software failures were a key part of the Terminal 5 fiasco (T5) last month, but it is still unclear whether British Airways (BA) or BAA are responsible, a Commons Transport Committee heard yesterday.

BAA is responsible for the contracts with IT suppliers, and so takes part responsibility for costly baggage system errors in the first three days of T5 opening.

But BA is responsible for training staff to use the systems correctly, including the correct procedures in the event of software failure.

"We compromised on the testing regime and this impacted on operations, but this was because of delays in the completion of the building programme," said BA chief executive Willie Walsh.

However BAA were responsible for the building programme, and thus for rushed testing.

"The totality of the testing regime did not adequately reflect the first few days of operations," said BAA chief executive Colin Matthews. "There were then a number of problems that arose very specifically from within the software."

These software issues were identified relatively quickly, but the knock-on effect on operations became catastrophic, said BAA non-executive chairman Nigel Rudd.

Neither BA or BAA currently plan to sue any suppliers.