The Civil Aviation Authority says helicopters in London have only limited radar help and fly mostly using visual reference points on the ground.
Certain designated routes for helicopters are in place to "provide maximum safety by avoiding flying over built up areas as much as possible," it says.
Nearly 170 flights followed the central London route along the Thames in December, its figures show. About 250 flights arrived and departed from the heliport at Battersea in the same month.
Wednesday's crash caused major disruptions for many people on their way to work.
Vauxhall, with a rail station, Underground station and large bus station, is an important transit point for those traveling from the south to other parts of London.
The Nine Elms area between Vauxhall and Battersea has been earmarked as a major regeneration site, with plans to create 16,000 new homes and 25,000 new jobs.