Volcanic ash from Iceland has seen a number of airports in the north of Scotland closed by National Air Traffic Services (NATS).
While most airspace across the United Kingdom remains available following Wednesday reopening, Kirkwall, Wick and Inverness airports were all closed late on Thursday night.
An existing no-fly zone over parts of Scotland had already seen Stornoway airport closed, with all four locations likely to be unavailable until at least midday today.
However, Highlands and Islands Airports – which operates the airports – confirmed its seven other properties would be open as normal.
Passengers are requested to check with airlines before departure.
Returning to normal
NATS has confirmed aviation traffic over the UK approached 80 per cent of normal levels yesterday - with 2,860 flights handled before 16:00.
At this time of year, the air traffic body would expect to be dealing with fewer than 5,000 movements every 24 hours and the current numbers reflect the numbers of airlines which still have aircraft out of position.
NATS expected to be dealing with 90 per cent of usual traffic today.
“Conditions around the movement of the layers of the volcanic ash cloud over the UK remain dynamic,” explained a statement.
“NATS will continue to monitor the latest Met Office information and the CAA’s updates on the density of the ash cloud across the UK.”
As the dust settles, UK airlines have begun to question government actions during six days of closures.
While the Civil Aviation Authority (CAA) and NATS have insisted the flying ban was necessary if any traces of ash were found, airlines have stated low-levels of volcanic ash were acceptable, subsequently branding the government response “shambolic”.
Some analysts are also questioning the length of the flight ban.