BBC reports that the West Midland Air Ambulance has stopped flying due to the ash plume.
BBC News - Volcanic ash grounds West Midlands air ambulances
Volcanic ash halts air ambulances
Air ambulance services in the West Midlands region have been grounded after the Icelandic volcanic eruption.
The Warwickshire and Northamptonshire, Midlands and Derbyshire, Leicestershire and Rutland services were grounded at 1200 BST on Thursday.
Crews from the five helicopters were redeployed in rapid response cars.
West Midlands Ambulance Service said it was waiting for advice from the Civil Aviation Authority to find out when it would be safe to fly.
The Midlands Air Ambulance service, which has three helicopters, operates from RAF Cosford in Shropshire, Strensham Services on the M5 in Worcestershire and Tattenhill in Staffordshire. The Warwickshire and Northamptonshire service has a helicopter at Coventry Airport and the Derbyshire, Leicestershire and Rutland facility is based at East Midlands Airport.