how come they say that gatwick is a single runway airport when it has 2???
Only one is usable at any one time. The separation is inadequate for dual operation. An aircraft executing a missed approach of one runway would be dangerously close to one taking off from the other.
That's why the one closest to the terminal is generally used as a taxiway or as a backup.
But there is only one that can be use for t/o and landings 08R/26L
It's the separation issue, and why Manchester had its second runway staggered. One aspect of the MAN
design was to introduce additional spacing of aircraft if both are in operation and there was an aborted landing at the same time as a takeoff on the other runway.
The landing aircraft can execute a turn away from the centreline before coming into conflict with the departing aircraft. Gatwick's layout precludes that, even if the two runways were developed to be physically identical. It would require a greater separation, like that at LHR
with the terminals between the runways or in the US
with a greater distance between active runways.