A NO-FLY zone is operating above Edinburgh Zoo in a bid to boost giant panda Tian Tian’s chances of having a cub.
Zoo chiefs fear the noise from low-flying planes and helicopters could cause the pregnant giant panda to lose her cub.
Zoo bosses said the restriction was originally brought in to help breeding penguins but now helped protect Tian Tian, who is due to give birth on August 31.
Hopes are high that Tian Tian will produce a panda cub after two years of disappointment.
An official Notice to Airmen (NOTAM) was issued in mid-July.
A zoo insider said: “The main reason for the NOTAM was for the penguins as it’s their main breeding time.
“But the Panda was also a factor.”
A CAA spokesman confirmed that they did issue the notice based on a request from the zoo.
The spokesman said: “Following a request from Edinburgh Zoo through the Air Traffic Control Unit at Edinburgh Airport, we issued a Notice to Airmen (NOTAM) on 11 July requesting pilots to not fly within a one mile radius of the zoo or below 1,900 feet above sea level.”
The official notice expired on July 31 but Edinburgh Airport said an informal arrangement was still in place to avoid zoo airspace.
A spokesman said: “We can’t enforce people not to fly so it is a request to helicopters and small planes.
“The request has come from the Zoo and Edinburgh airport and air traffic control are happy to work with.
“So we’re requesting that aircraft do not fly over the Zoo.”
The normal flight path for commercial jets approaching Edinburgh Zoo rarely takes large aircraft closer than two miles.
Edinburgh Zoo said in its official statement that the no-fly request was “to prevent disturbance to all animals in the collection”.
“It is particularly relevant at this time of year due to the regular increased activity of low flying aircraft and hovering helicopters which occur as a result of the festival.
“We have been in contact with the Military Tattoo and the RAF for several years now and they have both always been very supportive and considerate of our requests.”
Police Scotland was made aware of the notice and took it into account when flying its helicopter in Edinburgh.
However, the force was prepared to fly over the zoo if necessary in an emergency.
Last year experts believed Tian Tian became pregnant last year but lost her cub at late term.
Although panda pregnancies are notoriously unpredictable, the latest scientific data suggests she is on course to give birth on August 31.
Other NOTAMS in Scotland in recent days include a warning about a model rocket firing an event in Ayrshire.
Along with an air display in Strathaven, a fireworks display in Dumfries and kite flying in Girvan.