Planes taking off at Heathrow follow NPR routes until they reach an altitude of 4,000ft, at which point they are directed by air traffic controllers towards their final destination. However, there may be times when aircraft are directed by NATS air traffic controllers to leave the departure routes before 4,000ft. Reasons for this can include traffic avoidance (e.g. police helicopters) and weather avoidance (e.g. thunderstorms) or safety reasons.
From 3 April onwards users can view which aircraft have left the NPR before reaching 4,000ft, including the time and height of deviation. These flights will be highlighted in orange from the beginning of take-off so it will be easy to see which flights have left before reaching 4,000ft.
Overall, track keeping on Heathrow’s departure routes is very high at around 98%, with the exception of the Compton route on easterly operations which has historically been much lower. Each month we report on the monthly track keeping stats for each NPR, these can be found here.
WebTrak can be found here.