Flying is not "the enemy" in the fight against climate change, the chief executive of Heathrow Airport has said.
John Holland-Kaye told the BBC's Today programme: "The answer is not to stop people flying. It has to be about decarbonising aviation."
The UK's aviation industry is promising to reduce its net carbon emissions to zero by 2050.
Cleaner engines, new fuels and planting trees will all help, according to the industry group Sustainable Aviation.
Mr Holland-Kaye said: "The enemy is carbon, not aviation. We need to protect the ability to fly in a world without carbon.
"When the government blocked Heathrow expansion 10 years ago, people started flying through Amsterdam and Paris instead, taking two flights instead of one and not a single tonne of carbon was saved."
He said synthetic fuels were the way forward. "It has been around for about 100 years and is becoming more affordable. It needs a real push on investment."
'Crisis is here and now'
Sustainable Aviation says the industry's plan will mean airlines can cut pollution even as passenger numbers grow by an expected 70%.
But campaigners say the only way to cut airline pollution is by reducing air travel and cancelling new airports and runways.
"We need to restrict flying," said Muna Suleiman, from Friends of the Earth. "We can't have airport expansion at the same time."
Rail travel and buses are greener alternatives and taxes should be applied to frequent fliers, she said.
Biofuels, which Sustainable Aviation say will be part of the industry's plan, still pollute, Ms Suleiman added. "The crisis is here and now."
The aviation sector is under increasing pressure to come up with a plan to cut emissions, especially as it has no commercial comparator yet to the electric car, which is seen as the auto industry's hope for cutting emissions.
While other forms of transport produce more carbon, individual journeys on planes produce large amounts of CO2.
Sustainable Aviation says the UK industry can reduce its emissions of CO2 from 30 million tonnes a year to zero, without restricting growth.
An economy-class return flight from London to New York emits an estimated 0.67 tonnes of CO2 per passenger, according to the calculator from the UN's civil aviation body, the International Civil Aviation Organization.
That is equivalent to 11% of the average annual emissions for someone in the UK or about the same as all of those caused by someone living in Ghana for more than a year.
US firm Wright Electric said last week it had started electric engine development for a 186-seater plane, and hoped to begin test flights in 2023.
British Airways is investing in a project to make fuel from rubbish.
Source: BBC