Airport operator BAA's response to the pre-Christmas snow was "initially ineffective" leading to "distress" to passengers, a report into the December 2010 travel chaos said today.
Confused and contradictory messages caused incorrect signals to go to airlines and passengers, said the BAA-commissioned report.
The potential impact of the weather forecast was not fully anticipated in the days before the worst of the snow on December 18, the report said.
This led to "a low state of preparedness ahead of the snow and insufficient stock of critical supplies for an event of this scale", the report said;
Clearing the aircraft stands was slower than required and slower than rates achieved elsewhere.
This was because the condition of snow on stands became very difficult as a result of earlier aircraft de-icing and stand gritting. Airlines and BAA had not agreed priorities and protocols for dealing with and resourcing this situation. BAA did not have specialised equipment for under-aircraft stand clearance.
The report recommended that Heathrow adopt an improved winter resilience target that the airport should never close as a result of circumstances under its control, except for immediate safety or other emergency threats.
BAA said it accepted the report and was developing a £50 million resilience investment plan which it would recommend to airlines and the Civil Aviation Authority next month.
Led by BAA non-executive director Professor David Begg, the inquiry was set up by BAA on December 23 after the airport had started to return to normal following the heavy snow on December 18.
Thousands of Christmas getaway passengers had to camp in the terminals at the west London airport as airlines cancelled hundreds of flights.
In the report, the inquiry team said that no single event or decision led to the disruption in the period December 18-23.
It added that BAA's crisis management system was invoked on Friday December 17 to deal with congestion in Terminal 5.
The report went on: "The response to the snow on December 18 was initially not effective. There were failures in communication and co-ordination within BAA, and between BAA and airlines, which led to ineffective engagement between different parties, resulting in ineffective situational awareness and a delay in response and escalation.
"Confused and contradictory messages caused incorrect signals to go to airlines, to passengers, and from airlines to passengers.
"The executive crisis management team and the capacity constraints group proved effective in managing the crisis once invoked. Both groups should have been mobilised earlier."
The report continued: "Passengers experienced distress as a result of the disruption. There was an apparent lack of compliance, by some airlines, of European regulation relating to obligations towards passengers; there were different and conflicting messages about the state of the airport and of flights; and there was slow reaction to terminal congestion by BAA."
Among the recommendations made by the inquiry team were:
* BAA and all those involved with Heathrow, including airlines, should agree an enhanced Heathrow snow plan. This should aim to ensure that the airfield remains open at all times, except when it has to be closed for safety reasons;
* There is a need for BAA to strengthen its approach to emergency planning, response and recovery;
* On communications, a single physical control centre should be established for the management of major incidents, where parties can meet to make more informed decisions;
* On passenger welfare, BAA, together with airlines and retailers, should prepare and routinely test a sustainable welfare plan that can be triggered immediately. The plan should include measures to ensure adequate, trained people are available from BAA and the airlines and systems are in place to provide accurate information on flight and airport status.
One of the things that BAA has done in response to the report is set up a strategic board with British Airways, Virgin Atlantic, bmi, air traffic control company Nats and the Civil Aviation Authority to improve things for passengers at Heathrow.
This was welcomed today by Professor Begg, who added: "For us the single most important message from the inquiry is that all members of the Heathrow community need to work together.
"Many people worked extremely diligently and for long hours to serve passengers during the crisis period. Our aim has been to put the passenger experience at the heart of our recommendations."
BAA said its £50 million would allow the airport to implement the recommendations in the Begg report.
BAA chief executive Colin Matthews said: "Our aim is to better serve passengers in normal times and at times of disruption, whatever the cause.
"If the entire Heathrow community learns from this report, and works more collaboratively to promote passengers' interests, then this is a pivotal moment for the airport and its reputation."
He went on: "We clearly understand our role in keeping Heathrow open, unless for emergency or safety reasons, but to do that and to achieve the highest standards of passenger care, we need to work more closely and collaboratively with airlines and them with us, and all agree on the necessary training and investment.
"Heathrow is among the most congested airports in the world and the lack of spare capacity means that unlike every other British or European airport, we have literally no room to move when disruption occurs. This means that any problem, large or small, that slows down the rate of aircraft arriving at or leaving from Heathrow, will disrupt many people.
"Passengers will win as airlines, the airport and others work together and in some cases put aside historic differences to make Heathrow a better experience for passengers."