Through a number of phases of the modern age, different airlines have attempted to offer air-taxi services from the three main airports around NYC to Manhattan. The economics would seem to make sense at first blush. The relative distances, potential market demand and locations make sense. And, yet none of the big airlines still offer these ad-ons to their mainline service, while, at the same time, they have offered significant incentives to attract big-money customers. The natural conclusion is that the devil is in the details and there must not be sufficient demand or market support for the routes to make financial sense. Not the least of which is that the fraction of the population who feels comfortable riding in a helicopter is small (consider how many people intensely dislike propeller planes, and then understand that helicopters are worse in nearly every way for ride experience when compared to jet flight).