THE day two aircraft collided over the north of the borough has been marked by the family of one of the crew and by a man who was there as a teenager.
After the catastrophe of July 4, 1948, some of the debris of one of the aircraft, an Avro York, was scattered near Mount Vernon Hospital in Rickmansworth Road, Northwood, and the fuselage landed in woods near Battlers Farm in Harefield.
The other aeroplane involved in the worst ever British mid-air collision was a Scandinavian DC6, much of which was strewn in Copse Wood, Ruislip.
Keith Hayward of the Chiltern Aviation Society was only 19 at the time, and camping with the 1st Ruislip Rover Scouts in Mad Bess Woods, Ruislip, when he heard the bang.
Mr Hayward, of Pinn Way, Ruislip, who is now 79 and honorary consultant archivist for BA archives and museum, said: "It was a foul weekend with low cloud and rain, and we were just packing up early from our camp when we heard an aircraft engine fairly close.
"This was followed by the most awful crunch, like a massive car accident, then a roaring which ended with a terrible crash.
"We looked north and saw the smoke in the distance and ran from Mad Bess woods to Battler's Wells Farm woods, where we came to an amazingly small clearing.
"It was blazing like mad and there was a black mass where there were seven dead - six crew and the High Commissioner for Malaya, Edward Gent."
Mr Hayward, who was doing his national service at RAF Uxbridge at the time, recognised the plane as a York and later discovered that the two aircraft, which had been heading for Northolt and had been in a holding pattern, had just been cleared to be diverted - the York to Hurn (now Bournemouth) airport) and the Swedish aeroplane to Amsterdam, when the accident happened.
Some of the family, including the daughter and grandson of Flight Lieutenant Ingleby who died in the York, recently returned to the scene after contacting Ruislip historian, Eileen Bowlt, who put them in touch with Mr Hayward.
Mr Ingelby, whose grave is in Derby where the family hails from, had carried out 60 operations for bomber command in World War Two, only to die in this accident after hostilities had ceased.
Amazingly the relatives, who were accompanied by Mrs Bowlt and Mr Hayward, found the crash spot and laid flowers where there were blackened tree stumps.
This was followed by a quiet moment of reflection in which they remembered the dark day 60 years ago that left 39 dead.