Many passengers faced delays or cancellations at T5's launch
Disruption surrounding the opening of Heathrow's Terminal 5 could have been avoided if union concerns were listened to, MPs have been told.
Union leaders told the House of Commons Transport Committee that no consideration was given to their views.
The launch of the £4.3bn terminal in March was criticised as a "national humiliation" following glitches in the new baggage-handling system.
Managers said they ran out of time to fully test the system.
Chaos quickly ensued causing flights to be cancelled and bags to go missing.
Lifts were also left out of action and staff struggled to get through security.
The problems cost several top executives their jobs.
Steve Turner, from the union Unite, said: "British Airways and (airport operator) BAA were working together over the opening but there was a complete failure to consult the trade unions."
Iggy Vaid, a senior shop steward with Unite, said: "We were told this was a state-of-the-art building.
"Everything was going to work. Everything was going to be all right.
"We had a lot of teething problems with the opening but these could have been avoided had we been listened to, but we were not."
Colin Matthews, BAA's chief executive, said he had not found any evidence of concerns in writing from those worried about T5 in advance of the opening, although he conceded that there would probably have been verbal discussions.
Despite claims from the unions that more than 900 bags a day belonging to transfer passengers were going missing at Terminal 5, Mr Matthews insisted it was "working well".