One argument behind the status quo at Heathrow is about the reduction of harmful emissions, but the stacking process that hits over half of all flights means airlines use more fuel per route mile flying into Heathrow than many other airports.
More than half of planes flying into Heathrow are forced to circle the airport waiting for a landing slot, for as long as three quarters of an hour.
Latest figures confirm the experience of many passengers who can find themselves stuck in a holding pattern – known as a stack – for up to 20 minutes on a normal day and 45 minutes in bad weather.
In some cases the time spent waiting for a landing slot can be as long as the flight from short-haul destinations in France, Belgium, and Holland.
The statistics from NATS, the company responsible for air traffic control, will intensify pressure on the Government to reconsider its opposition to building a third runway at Britain’s busiest airport, which is now being questioned by senior backbenchers and some ministers.
Justine Greening, the Transport Secretary, is drawing up a strategy for aviation capacity and is due to announce a “call for evidence” from the industry within weeks.
However the figures from NATS have laid bare the impact on daily operations of an airport which is bursting at the seams.
In 2010, the last year for which statistics are available, 120,425 of 224,497 incoming flights at Heathrow were held in a stack, over Bovingdon; Hertfordshire, Lambourne, Essex; Ockham, Surrey and Biggin Hill, Kent.
By comparison, 16,541 of Gatwick’s 120,250 income flights were held in a stack and at Stansted the figure was 3,786 of 77,570.
Although stacking figures for other major European airports are still being compiled, pilots regard Heathrow as having the most serious problem because it is struggling with only two runways, while its major rivals have four.
Earlier this week The Daily Telegraph disclosed that Heathrow was also responsible for more aircraft being stuck on the tarmac waiting for clearance to fly than any other airport in Europe.
The worst delays are normally in the morning from 6-8 am and it is not uncommon for some business executives to fly in London the night before for a meeting, rather than risk being late because of congestion in the skies.
According to NATS statistics, the delays are not only causing operational difficulties but are also causing environmental damage.
It calculated that Heathrow was responsible for 91.4 per cent of the carbon emissions from stacking aircraft in Britain as a whole, with a total of 277,900 tonnes in 2010.
“Stacking delays are anathema,” said a spokesman for the Association of European Airlines.
They have a substantial environmental cost and they play havoc with the airlines’ schedule integrity. They also severely impact our customers, when an on-time departure turns into a significantly delayed arrival.”
A spokesman from the British Association of Airline Pilots added: “The amount of stacking at Heathrow is clearly a problem and is a symptom of the capacity constraints we have.
“Not only is holding for extended periods around Heathrow annoying for passengers, a poor welcome to the UK and bad for business, it is also needlessly damaging for the environment.
“One thing that may not be figured into official holding statistics is extended flight paths pilots have to sometimes fly after leaving the stack which can add another 30 miles of flying and additional time onto the approach.”
Business leaders also said the figures intensified the need for additional runway capacity at Heathrow.
‘If you have the national hub airport operating at 97 per cent capacity, you don’t have much slack to deal with unexpected events like bad weather, which seems to have been the main cause of delays at Heathrow,” said a spokesman for London First.
“A third runway would provide much-needed resilience, but, at the very least, the government should allow it to use its existing runways more flexibly.’
Mike Carrivick, chief executive of the Board of Airline Representatives in the UK, added: “Airlines waste thousands of litres of fuel stacking.
“It is environmentally unfriendly, inefficient and delays passengers unnecessarily”