Every day more than 600 planes take-off from Heathrow. The majority head off in a westerly direction, as the westerly is the prevailing wind in London. Until the planes reach 4,000ft there are specific tightly controlled routes in which they can use. Could this be one of the 777s with the Rolls Royce engines that have been falling out of the sky due to a fault in de-icing equipment that stops fuel getting to the engines. British Airways has 15 of these in it's fleet of 44 777s - so 29 with a different engine and without the fault. However, they have said they cannot tell passengers if they will be flying on the planes with the fault or not for "logistical" reasons!!!A consideration when buying a property in these areas.
As always visit other skywatchers around the world. 
