Mental tasks are impaired at high altitude, so dealing with key emails is best avoided, says David Gradwell. Passengers should follow health advice to avoid side-effects such as jet lag and dehydration, he says.
"Flying is safe," he told a news conference. "Millions of people do it every year without any issues at all."
Prof Gradwell, of King's College, London, said most people could tolerate cabin pressurisation quite well. But he said learning was a little impaired at a higher altitude, as was performance of recently learned tasks.
"It's perhaps not where you want to make the most important decision of your life," he said.
"Those of you who are looking forward to having emails in flight might want to think twice about sending that email to your bank manager."