UK Travel News
The incident began on the day the UK was originally due to leave the EU.
The firm's shares plunged more than 8% as probe into fatal crashes continues.
The German-based firm owns 15 of the planes, including five within its UK operation.
He said the safety of the American people is of “paramount concern”.
The move comes after the Ethiopian Airlines crash, which killed all 157 people on board.
157 passengers and crew were killed when the jet crashed shortly after takeoff on Sunday morning.
TUI, which has 15 of the planes worldwide, will not ground its fleet.
Forecasters said not everywhere would be affected, but some dense patches could reduce visibility to as low as 50 metres in a few places.
In December, London's Gatwick Airport was closed for days after drone sightings.
Many bus routes in England receive partial or complete subsidies from councils.