Mr Bacon asked how many journeys had been height capped at Swanwick and over the previous three years at West Drayton. For Committee members who may be less familiar with the terminology, "height capping" is simply a technique whereby an air traffic control provider is able to offer airlines a more prompt service at a lower flight level. It is generally more fuel efficient for aircraft to cruise at higher levels, but height capping is an alternative to delays when the requested flight level in the upper air routes is not available-eg because it is occupied by other traffic. It is true that in the summer season this year, there was a significant increase in the number of pilots accepting lower-level routeings, but this has now returned to more usual levels.
No statistics are kept on the numbers of flights that are height capped.