Parts of UK airspace are at risk of lockdown again.
The Department of Transport has said wind was blowing volcanic ash from Iceland towards the South East of the British Isles.
If the ash is deemed to pose a risk to aircraft, disruption could last until Tuesday, when winds are predicted to change, the Met office said.
The new Transport Secretary Phillip Hammond said the situation was "fluid", but insisted passenger safety would be top priority.
BA said it was in discussions with air traffic control body Nats and airport operators at Heathrow and Gatwick.