Airports across Scotland, Wales and Northern Ireland will remain shut until at least 1pm BST today as volcanic ash from Iceland disrupts flights once again.
Heathrow and Gatwick airports in the UK were closed from 1am until 7am today, following a day of closures across the country on Sunday.
The UK's National Air Traffic Service (NATS) said yesterday that restrictions have also been imposed on Shoreham and Biggin Hill airports in the UK, and all airfields in Northern Ireland, Scotland and Wales.
Airports in the Republic of Ireland suffered less disruption with most reopening by Sunday night, but Donegal, Sligo and Ireland West (Knock) remained closed this morning.
Amsterdam's Schiphol Airport and Rotterdam Airport in the Netherlands have been closed since 6am CEST on 16 May and will remain shut until 2pm today.
The UK's Civil Aviation Authority (CAA) said the ash cloud is changing shape and drifting south towards Oxford, England.
On 16 May, German authorities sent one test flight from the German Aerospace Center (DLR) and another from Lufthansa to measure the ash cloud.
The DLR plane collected data from between 10,000ft to 23,000ft, while flying from southern England to north.
The Lufthansa Airbus A340-600, equipped with special scientific equipment, left Frankfurt to fly over northern Germany, the UK and parts of Scandinavia.