DaveReidUK said:-
None of the LGW expansion options involve only being able to operate one runway at a time, for obvious reasons.
Yes they do. That option is called the Close Parallel Runway. The nature of the Gatwick airport site is such that there are issues with aircraft taxiing across the end of the existing runway with even the the two wider spaced runway options but there is unikely to be a problem constantly taxiing across the end of a runway that is closed unless that is the exact point where the crash has actually taken place.
See
www.gacc.org.uk/resources/Gatwick%20Unzipped%20pdf.pdf and
AirportWatch | Gatwick publishes its 3 options for a southern 2nd runway enabling up to 87 mppa
That is why in their submission GAL state that:-
50. The runways would have to be used dependently i.e. operations on one runway temporarily interrupting operations on the other.
51. A close parallel runway would provide comparatively little extra capacity. GAL state that the existing runway can handle 40 million passengers a year, rising to 48 million by 2050. A new close parallel runway would raise this to around 60-66 million. Thus the increase in capacity could be as little as 25%.
DoorsToAutomatic said::-
Just out of interest why was Gatwick's emergency runway not brought into use? I thought it was there for this very eventuality?
Because its only designed to be used when the main runway is temporarily out of use being inspected or resurfaced or repaired or otherwise maintained (eg new landing light system installation) but is far too close to the main runway to ever be safely operated when an aircraft (especially a 747) is standing on that other main runway.
Anyone who knows anything about Gatwick knows that the current so called "second runway" is just a glorified taxiway (its normal function the rest of the time) that is only used basically as a last resort and mainly at night (typically from midnight to 5am and probably not for any length of time overnight in July or August when there are far more middle of the night arrivals than during the rest of the year) when there are relatively few aircraft operations that will actually need to use it and hence the lower safety factor and clear extra risk involved in using it is minimised.