Cover: the traditional Battle of Britain Memorial Flight formation of the Lancaster, Spitfire and Hurricane approaching Buckingham Palace in July 2005. (Picture: MoD)
The weather is the biggest factor that could hamper the flypast marking the centenary of the Royal Air Force, the officer who planned the spectacle has said.
With up to 100 aircraft set to plot a course over The Mall and Buckingham Palace on 10 July, Heathrow Airport will close for 20 minutes.
The Lancaster, Spitfires, Hurricanes and Dakota planes set to feature will also avoid the skies over Wimbledon so the tennis championships will not be disrupted.
Wing Commander Kev Gatland, the project officer responsible for the display, said everyone in the RAF "will be rooting for the weather to be fit":
"The biggest risk really that we will see on the day will be the weather, in all honesty."
There are four plans in place for the flypast. The main one includes 100 aircraft and will be used on the day if conditions are right.
Another three have been created, with a decrease in the number and types of aircraft if the weather is unfavourable.
It will not be until the final weather reports have been received and reviewed on the day that a decision will be made on which plan will be used.
Wing Cdr Gatland, a Tornado navigator, said if the conditions are too poor the flypast will be cancelled:
"Whilst in London it can be completely blue skies, if there was a thunderstorm over the north Norfolk coast, over The Wash area, and that meant those aircraft couldn't hold or form up safely, then those aircraft won't participate.
"It is not just about what is happening over central London, it is what the weather is doing in the ingress, the egress, and in the holding areas.
"All of that has to be fit and good enough to allow the aircraft to legally and safely fly through."
He said aircraft will also be grounded if they are not deemed to be in a serviceable condition, with safety paramount to the flypast.
A large area of airspace above the capital and surrounding areas, including the Norfolk coast, Colchester and Ipswich, will be restricted and used only by the aircraft taking part.
"It is a huge bit of airspace that we are utilising. But, we are trying and have tried in the planning to minimise the time we need but also the heights we are taking as well," Wing Cdr Gatland said.
Heathrow Airport will close for about 20 minutes, and arrivals and departures at the international transport hub will cease.
Wing Cdr Gatland said this is three times longer than for the flypast after the annual Trooping the Colour for the Queen's birthday.
He said officials spoke to Heathrow early in the planning so measures could be put in place to keep disruption to a minimum, and arrivals and departures could be "subtly shifted" to eliminate delays throughout the day.