Flights from Newquay to the Isles of Scilly are not restricted
Most flights in Cornwall have been halted for a third day because of a cloud of volcanic ash from Iceland.
Restrictions in controlled UK airspace led to the grounding of all flights at Newquay apart from those travelling to and from the Isles of Scilly.
They were imposed amid concerns that particles of rock, glass and sand in the ash could damage aircraft engines.
Restrictions by the air traffic control body Nats have been extended until at least 1900 BST on Saturday.
Cornwall Air Ambulance had grounded its helicopter on Thursday afternoon for almost 24 hours as a precaution but reinstated it for operations shortly before 1400 BST on Friday.
Crews on standby
Paula Martin, the service's chief executive, said the decision to ground the aircraft was made because the consequences of the engine being damaged would result in the service being out of action for a longer period of time.
However, she added that crews had remained on standby throughout the restrictions.
Flights to and from the Isles of Scilly have not been affected by the restrictions because the aircrafts using this route fly at 1,500ft, which is below controlled airspace.
Richard Thomasson, operations manager at Newquay Airport, said: "All these restriction issues are in the upper airways but our flights to the Isles of Scilly are not in controlled airspace because they fly at a lower level.
"As a result, passengers which were due to fly to the Isles of Scilly from Bristol and Southampton today are being brought down by road to Newquay so they can fly from here."
Nats extended the restrictions following advice from the Met Office which has been monitoring the ash cloud created by an eruption in the Eyjafjallajoekull area of Iceland.