And helicopters can do that today, but traditionally, helicopters have been just a little bit too expensive, just a little too hard to pilot and just a little too noisy to be used for daily transportation in cities.
Os helicópteros fazem isso, hoje, mas, normalmente, os helicópteros são demasiado caros, demasiado difíceis de pilotar e demasiado barulhentos para serem usados no transporte diário nas cidades.