Originally Posted by Боб Уайтман
Just влететь in this context means "to fly into a closed space", you can
влететь в комнату, влететь в окно, влететь внутрь, влететь в ворота (in football sense). But you cannot use this verb when you mean arriving to a place (city/country etc.) by plane.
Just use прилететь for arriving by air. It's the same way as you use приехать (by arrive by riding), приплыть (to arrive by ship) or прийти (to arrive by foot) etc.
London is not a closed 3-D space where you can fly inside it :) You just arrive to there.