Air traffic above London is restricted Wednesday for the procession of Queen Elizabeth II's coffin, Heathrow Airport said.
A number of flights "will be disrupted to ensure silence" as the procession takes place, London's biggest air hub said in a statement.
Flights face restrictions as the queen's coffin is carried from Buckingham Palace to Westminster Hall, where the late monarch will lie in state until her funeral on Monday in Windsor, west of London.
Heathrow has meanwhile flagged more likely disruption for Monday.
"We anticipate further changes to the Heathrow operation... when Her Majesty's funeral is due to take place, and will communicate those in more detail over coming days," the airport added.
"We apologise for the disruption these changes cause, as we work to limit the impact on the upcoming events."
British Airways confirmed it had cancelled eight European flights due Wednesday.
The Civil Aviation Authority regulator has imposed airspace restrictions over central London, banning non-standard aircraft including drones flying below 2,500 feet (760 metres) between September 9-19.