Heathrow boss slept through first six hours of fire shut-down - because his phone was on silent

The boss of Heathrow was unaware of the substation fire that shut down one of the world's busiest airports for more than six hours - because his phone was on silent.

A review into the fire on the night of March 20 into March 21, disrupting more than 200,000 passenger journeys, found that the airport's chief executive, Thomas Woldbye, was called when the fire broke out but did not answer his phone.

The phone was muted 'without him being aware', the Kelly Review concluded, and he only became aware at 6.45am, more than seven hours after the fire broke out at 11.20pm on March 20.

Chief operating officer Javier Echave attempted to call his boss 'several times' during the night, raising what is known as an F24 alarm to activate emergency command response teams, but did not hear back. 

As detailed in the 75-page report, Mr Woldbye told the he felt 'deep regret' at not being contactable during the incident. 

His lack of involvement, the review ultimately found, 'had no impact' on decisions made overnight, as he was not on the 'command and control' roster for emergencies.

His account in the Kelly Review, which concludes that the airport 'responded well' to the fire, contrasts with earlier reports in the Sunday Times that Mr Woldbye went back to bed after being awoken to be told of the blaze.

The review, led by former Labour Transport Secretary Ruth Kelly, concluded: 'Both Mr Woldbye and Mr Echave confirmed to us that this was not correct.'

Heathrow Airport chief executive Thomas Woldbye spent six hours unaware his airport was out of order after a substation fire - because he was asleep

The fire at the North Hyde substation could not be tackled for six hours, the Kelly Review concluded

The review concluded the way in which the airport closure had been handled was 'correct' - despite over 1,200 flights and 200,000 passengers being affected

Concluding that closing the airport was the 'correct... and essential' decision, Ms Kelly said the fire at the North Hyde substation had been 'unprecedented'.

She also said the decision by Heathrow bosses to wait until March 22 to fully re-open was equally wise, given the fact that safety checks needed to be carried out after power was restored before full service could resume. 

Had the airport attempted to reopen earlier, similar levels of passenger disruption still would have occured. 

'The evidence confirms that Heathrow made the right decisions in exceptionally difficult circumstances,' she said in a statement accompanying the report.

'Whilst the disruption was significant, alternative choices on the day would not have materially changed the outcome. 

'The airport had contingency plans in place, and the report highlights that further planned investment in energy resilience will be key to reducing the impact of any similar events in the future.'

The shutdown of the North Hyde substation prompted questions over why Heathrow was not prepared to cope in the event of a total power loss, and why it took 18 hours for power to be fully restored.

But the report has revealed that the power loss crippled vital safety systems and infrastructure including an airport fire station.

Security staff in Terminal 2 had to use the torches on their phones to see at night because of the total loss of power. 

London Fire Brigade officers also told Heathrow they would not be able to safely bring the fire under control for at least six hours. 

The smouldering remains of the North Hyde substation after it was consumed by fire. An investigation is ongoing into the blaze

The review found that Heathrow security staff were forced to rely on phone torches to see inside Terminal 2 (pictured: people using their torches at Terminal 4's car park)

Firefighters are seen dampening down the substation - which was 60 years old at the time it caught fire. The cause remains unknown

Passengers sitting outside Heathrow Terminal 5 on March 21. The airport says it will learn from the incident in order to be 'more fit for the future'

Passengers were told not to travel to Heathrow on March 21. It fully reopened the next day after safety checks were carried out 

The cause of the fire remains under investigation, with a full report from the National Energy System Operator expected in June

Interim findings published by the National Energy System Operator (NESO) earlier this month found power was restored to a chaos-stricken Heathrow around seven hours before flights were allowed to resume.

The electricity was switched back on for all four terminals - Terminal One no longer being in use - at 10.56am on March 21, almost 12 hours after the fire broke out. 

Heathrow airport said the report raises 'important questions' for National Grid - which owns the substation that caught fire - and Scottish and Southern Electricity Networks (SSEN), which is responsible for power distribution in the area.

In all, 1,273 flights were disrupted by the near-24-hour closure. Economists estimate that the fire cost the UK up to £4.8million in lost tourism alone.

But not a single Heathrow employee interviewed for the review disagreed with the decision to close.

NESO's full report is expected by the end of next month.

While the review was largely positive about the airport's response to the fire, Ms Kelly has issued 28 recommendations for Heathrow to consider.

They include firming up relations with SSEN - which is responsible for local power distribution - as well as ensuring emergency lighting is in place across terminals, and assessing whether to invest in additional back-up generators.

There is also a recommendation to have a 'second means of contact' for key individuals, such as CEO Mr Woldbye.

Heathrow Chairman Lord Deighton said: 'The Kelly Review is thorough with clear recommendations which the management team will be taking forward. 

'This was an unprecedented set of circumstances, but the learnings identified in the Kelly Review will make Heathrow more fit for the future.'