Dan has maintained, correctly, that dumping millions of aircars all at once into the *current* cities of our industrial society would not work because of the dynamics of flying in an atmosphere, with its winds and other changes of flight medium. What he does not bother with is that this would not happen. People are not going to do that.

What they will do is that very rich people will buy the first aircars, and those will be in the thousands for the first 3-5 years, during which time experience will be gained in keeping cars separate. These people will set the trend, by using their faster and easier transport to move farther out from city centers, and because of VTOL will find themselves traveling not from city center to city center, but from their house out in the mountains to the house of another rich person they want to meet with, usually equally far from a city center. As tech advances, and prices drop, the professionals who have moderately high incomes will begin using aircars, and following the Bill Gates crowd away from cities, since the primary function of cities, aggregating people in proximity to shorten travel times, will become moot for them, as well as for the very rich.

As prices drop further, and networked navigation among intercommunicating aircars becomes the norm, the cities as we know them today will begin to disappear much faster than they are now. Not only are larger numbers shopping online and other things making this easier, but the things that make city life harder are increasing, where agency costs for political hierarchies that can easily tax and manipulate any wealth in cities are becoming so evident. The growth of swaths in Detroit and other cities that are becoming de-urbanized to the point of becoming wildlife zones is not a coincidence. People are leaving cities that exhibit these agency costs, and aircars will only accelerate that trend.

Thus, to sweat bullets over aircars flying between high skyscapers is indulging in fantasy. The cities are dying, and aircars will have lots of airspace. As the author mentioned, an aircar would let him work between Philadelphia and Chicago as easily as someone in the Philadelphia suburbs does today in, …say, …Trenton. That increase in airspace over the area of current cities is at least two orders of magnitude. By the time those enormously larger skies fill up, the incremental development of aircar navigation technologies will be quite able to handle it.

For instance, Dan noted today’s 1,000 foot and 2,000 foot separations. Over a square metropolitan area only 30 miles square, that would leave volume for about 75X75 positions for aircars on any one level, with levels extending in his estimate up to 50, 000 feet. That is 281,000 positions in that volume. If we need 2/3rds of the positions to allow aircars to actually maneuver, as each does their intercomunicating robotic dance in the air, that’s only 90,000 aircars at any one time. Multiply this by the 100 largest cities between the Atlantic and the Mississippi, (holding the vast majority of total population there) and we have 9 million commuters at once, over land totaling 90,000 square miles. Not enough to move the Bos-Wash corridor commuters, much less the rest.

However, if we speak of a population spread out from the Atlantic to the Mississippi, and from the Great Lakes to the Gulf of Mexico, the calculation changes dramatically. This is an area about 600 miles on one side and over 1,000 on the other. At 650,000 square miles, we now have enough positions for 65,000,000 commuters flying at once. Not only that, but because we are able to use this huge area for routing via the intercommunicating navigation network, we will probably be able to get by with only 1/3rd of all the positions used for maneuver options. That gives us about 130,000,000 commuters safely moving swiftly to wherever and whomever they wish to see and work with, or play with, ……

We don’t have anything like that many commuters East of the Mississippi, and likely won’t. Technological advances will only enhance this situation. Aircars using structures like “fancloth” will be *far* more maneuverable, and far more capable of staying on course than present aircraft. The 2,000 foot horizontal separation can probably shrink substantially, as can the 1,000 foot vertical separation, multiplying available positions again. Of course, West of the Mississippi, the distances are greater, and the numbers look even more favorable.

The answer to cities that are already becoming unworkable, by being undrivable, much less unlivable, is to give up on cities as the primary residence for our population. We are already doing that. The aircar will only accelerate that trend.

However, your comment about parking is ass backwards. It would be far easier to get 500 aircars in or out of a 12 story garage because they could enter and exit at all levels and on all sides. A garage for groundcars has to have paths to all spaces and ramps up and down. In an aircar garage, all that could be omitted. Just make sure each floor is twice the height of any car; then each car can fly in and set down on a space. 100% use of floor space, everything’s flat (easier to build I bet).

The largest problems are regulatory. The FAA is very far behind in fulfilling its next generation ATC promises. That is all