Travel disruption has spread to the skies during the Queen's coffin procession with planes are banned from flying below a certain altitude over parts of London and Edinburgh.
The Civil Aviation Authority (CAA) said the ban has been enforced as part of wider security arrangements and applies in parts of the two capitals until the Queen is laid to rest on Monday.
It also includes “aircraft” such as personal jets, small balloons, kites and parachutes.
A spokesperson for the regulator has said this will create a “protective blanket” over the restricted areas, but will not affect commercial flights because they operate above the altitude limits.
Aircraft are not permitted to fly below 2,500 feet above mean sea level within central London until 7am on September 19, with potential for this time limit to be extended.
They have also been banned from flying below 6,000 feet above mean sea between Balmoral Castle in Aberdeenshire and the Palace of Holyrood in Edinburgh until 11.59pm on Wednesday.
This comes under the Restriction of Flying Regulations under Article 239 of the Air Navigation Order 2016.
London in particular is expected to be hit with unprecedented travel disruption in the days leading up to the Queen's funeral on Monday.
Bus, tube and train usage is likely to be exceedingly high, with Transport for London saying that cross city travel may not be as easy as usual.
People who can may be encouraged to work from home to ease the burden on the transport networks as much as possible.
Yesterday the official spokesman for Prime Minister Liz Truss acknowledged that commuters may want to adjust their work patterns accordingly.
"At this point we can't be more specific on numbers. We do expect it to be extremely busy," he said, Mail Online reported.
"I think for the Queen Mother it was around 200,000 people (who attended), we expect (it) to be far more than that for this lying in state."
Today the Queen's coffin will continue on a route down from Balmoral to London.
The oak casket will land at RAF Northolt after flying 400 miles from Edinburgh Airport today.
And fans will line the streets for the 15-mile journey to Buckingham Palace, where Her Late Majesty will rest for the evening as staff pay their respects.
At 2.22pm on Wednesday, the coffin will be taken on a gun carriage of The King’s Troop Royal Horse Artillery to the Palace of Westminster.
Accompanied by the sound of minute guns fired from Hyde Park by The King’s Troop Royal Horse Artillery, the cortege will make a trip past London landmarks.
