Getty ImagesHeathrow Airport was warned about the "resilience" of its power supply days before it caused a fire which shut down the airport for over a day last month.
Nigel Wicking, chief executive of the Heathrow Airline Operators' Committee, told a group of MPs on Wednesday that he spoke to the Team Heathrow director on 15 March about his concerns.
Chief executive Thomas Woldbye apologised to the nearly 300,000 passengers whose journeys were disrupted by the closure on 21 March.
He offered his "deepest regrets" adding that the "situation was unprecedented".
He added that he recognised "the considerable inconvenience and concern it caused".
During the same select committee hearing, Mr Wicking said he expressed his concerns "following a couple of incidents of, unfortunately, theft of wire and cable around some of the power supply that, on one of those occasions, took out the lights on the runway for a period of time".
"That obviously made me concerned, and as such I'd raised the point. I wanted to understand better the overall resilience of the airport."
Mr Wicking added: "It is the most expensive airport in the world, with regard passenger charges, so from our perspective, that means we should actually have the best service."
Mr Woldbye said Heathrow realised "during the early hours" of Friday 21 March that "we were losing power to the airport".
"In our operations centre you would seen all the red lights go, that the systems were powering down," he said. "We had no information as to why."
"We then had a slightly later stage call from the fire department that the substation was on fire," he said.
Heathrow is supplied by three substations, but knocking out one caused loss of power to the airport.
Mr Woldbye said a third of the airport was powering down and that Terminal 2 was particularly affected, along with certain central systems. He added that it became "first and foremost a safety situation".
"We need to make sure, when a crisis happens, that people are safe," he said.
Safety critical systems such as runway, runway lighting and the control tower "switched in as they should", however, he said.
