The highlight of the event is the appearance of the Red Arrows who are flying two full routines in the wake of a brief but spectacular appearance at the opening of the Scottish Parliament.

Organiser Adam Smith: "Red Arrows a highlight"

But there are other treats for spectators including a dogfight between a Spitfire and a Messerschmitt 109, and displays by such classic aircraft as the Mustang, the Hurricane and the Tornado.

The spectacle is this year's biggest air show in Scotland following the cancellation of the annual RAF Leuchars event.

It was called off for the first time since World War Two because of the operational commitments of British and other NATO aircraft.

The Bristol Blenheim: Designed by a Scot

As a result, organisers of the Festival of Flight - being staged at the Museum of Flight in East Lothian - expect bumper crowds of up to 50,000 a day.

Their cause was also boosted on Friday by a flying display featuring the last airworthy Bristol Blenheim bomber in the world.

The restored aircraft flew over Balfron and Stirling as a tribute to two brothers recognised as outstanding aviation pioneers, Frank and Harold Barnwell.

The men, who came from the area, were the first to design, construct and fly a Scottish-built plane in Scotland.

Frank Barnwell went on to become an aviation legend in designing the Blenheim and a host of great airplanes from both the first and second world wars.

Festival organiser Adam Smith had no doubt what he considered the highlight of the air show over the weekend.

Parliament boost

"The Red Arrows flying over the Scottish Parliament opening was a real boost for us because it was a little taste," he said.

"Most people got just a few seconds of the aircraft flying over - we have the full 20-minute routine. I am really excited they are coming to my airshow."

Organisers would not announce flight times in advance to avoid last year's congestion on the A1 caused by spectators arriving simultaneously to watch key moments of the display.

Weather conditions are unlikely to be ideal for the show.

BBC Scotland's weatherman, Gordon McKinistry, said Saturday would be quite windy with showers. Sunday should be bright and warm with a chance of a shower.