Now air charter buyers can use their smartphones to grab the next available helicopter seat bound for the Hamptons. The new Blade app lets customers book a seat on an existing flight or charter a whole helicopter and then use the app to help fill the seats. The app is backed by New York City’s Liberty Helicopters. Flights booked on Blade take off from NYC’s East Side Heliport and land in South Hampton, East Hampton and Montauk, with return flights to Midtown’s West Side Heliport.