The ban on flights over England and Wales was today (April 16) extended until tomorrow at 7am at the least.
But NATS, the UK national air traffic control service, said it would lift the restrictions would be lifted at 7pm this evening over large parts of Scottish air space, including Scottish airports, and Northern Ireland.
The move follows talks between NATS and the UK Met Office.
The relaxing of restrictions in Scotland comes as the ash cloud from the Icelandic volcano continued to move southwards.
In a statement NATS said the relaxing of restrictions in the north would mean that North Atlantic traffic could operate in and out of Scotland.
NATS said: "We are looking for opportunities when the ash cloud moves sufficient for us to enable some flights to operate under individual coordination with ATC.
"Some aircraft were able to operate at Manchester this morning, although restrictions are now reapplied to Manchester.
"We hope there may be some opportunity from the north into Newcastle after 0100 (UK time) tomorrow - Saturday.
"We will review further Met Office information and at 2030 (UK time) we will advise further arrangements. In general, the situation is dynamic and subject to change."
It advised people planning to travel tomorrow to contact their airline.
Eurocontrol which control air traffic across Europe, said it expected about 11,000 flights to take place today, compared with the normal 28,000.
It said: "Airspace is currently not available for operation of civilian aircraft in the following countries/areas: Ireland, the UK, Belgium, the Netherlands, Denmark, Sweden, Norway, Finland, Estonia, the north of France including all Paris airports, parts of Germany including Düsseldorf, Cologne, Hamburg, Berlin and the airspace around Frankfurt, parts of Poland including Warsaw airport."
Heathrow Airport said it had cancelled 1,250 flights today, affecting 180,000 passengers.
Yesterday it cancelled 899 flights.
Gatwick Airport said 730 flights would be cancelled today, affecting 90,000 passengers.
The airport cancelled 511 flights yesterday.
Many travellers are switching to rail with Eurostar yesterday reporting an increase of 10,000 in bookings on its cross channel services to Paris and Brussels.
Authorities in Ireland, France, Germany, Norway, Sweden, Denmark, Finland, Belgium and the Netherlands have closed all or parts of their air space.
Eurocontrol, the European air traffic control body, warned that disruption could last over the weekend.
There were also fears that countries further east, including Poland and the Czech Republic could be hit by the ash cloud tomorrow.
Lord Adonis, the UK transport secretary was today meeting with senior transport executives to see what contingency plans might be needed if the situation continues.
The ash is from the Eyjafjallajoekull volcano in south east Iceland.
Aviation experts have warned that particles of rock, glass and sand in the ash cloud could jam airline engines.
All four engines on a BA plane shut down when it flew into an ash cloud over Indonesia in 1982. The plane landed safety after the pilots got the engines to restart.
www.baa.com www.nats.co.uk www.eurocontrol.int www.gatwickairport.com