British pilots' leaders will fly to the US for talks on airline security amid concerns over flights cancelled because of American intelligence information.
Flight BA223 has been cancelled and delayed several times
The British Airline Pilots Association (Balpa) will ask the American airline pilots' association how intelligence is gathered and tested.
Balpa has also urged the UK Government to investigate US security information.
The visit comes after British Airways cancelled a flight to Saudi Arabia on Monday amid security fears.
Balpa said it had a number of outstanding issues to discuss in the talks.
General secretary Jim McAuslan said the association's priority was safety and security and that "whenever there is a specific, credible threat to a flight, it is quite right that the flight is cancelled".
"But pilots around the world, analytical because of the nature of their job, continue to ask questions and these questions have to be answered."
British Airways flight 263 to Riyadh had been due to fly on Monday afternoon but was grounded because of fears it could be the victim of a terrorist attack.
On Sunday, the airline cancelled flight 223 to Washington DC, a flight that has been much affected by security alerts in recent weeks.
The exact nature of the threat has not been revealed.
The latest cancelled flights were both due to depart from London Heathrow.
A BA spokeswoman said: "We take our lead from the advice we take from the government as to what action to take."
BBC security correspondent Frank Gardner said the UK Government had been acting on the advice of US intelligence but that the specific nature of the threat was unclear.
Flight BA223 from London Heathrow to Washington has been cancelled and delayed several times since the US raised its terror alert to high over the Christmas period.
After the previous bout of cancellations, government officials and air operators refused to comment on reports that flights had been cancelled due to a threat
At the time, the US Department of Homeland Security said that it remained "concerned about al-Qaeda's desire to target international aviation".