The proposed terminal, which Heathrow's owner BAA hopes will keep it at the forefront of commercial air travel, relies heavily in its design on the presence of such large commercial aircraft - to the extent of designing the terminal's gates to take planes with 85m wingspans, 20m wider than today's Boeing 747-400.
Opponents of the T5 project say they will step up their campaign before the planning inquiry, which is scheduled to resume in the next few months and is likely to continue into 1998. They are questioning forecasts by BAA that aircraft movements will only increase 8 per cent, despite a 60 per cent increase in the number of passengers going through the airport.
"Without the super-jumbos, the argument about all this passenger traffic not meaning many more flights, falls down," said one anti-T5 campaigner.
In a letter in the Financial Times on Friday, Jim Bailey, Surrey County Council's planning officer, called for the BAA plans to be revised to take into account the possibility that "more passengers will want to fly to more destinations on proportionately more aircraft".
BAA responded quickly, saying that Boeing's announcement "made no difference" to their plans. "We have to plan for an airport 20 years from now, and we would be mad not to take the super-jumbo into account," said a source close to BAA.
Michael Maine, BAA's technical director, added that the super-jumbo would only account for a small proportion of total flights at Heathrow, and the trend in any case was for aircraft in general to get larger and carry fuller loads. "We are looking to an increase in the amount of passengers on each plane, from around 130 today to approximately 180 passengers per average flight with T5," he said.