Wi-Fi in airplanes? Really? Oh, it seems sensible enough. We have Wi-Fi in libraries, restaurants, hotels, airports, and even city parks. But in airplanes?

Think back as to how Wi-Fi works. A land line, (copper or fiber) goes from the telephone central office to a particular location, and to what is called an access point at that location. That access point is nothing more than a modem, and it includes a radio transmitter. The signal being sent (or received) from that radio transmitter is short range – you can't ride a city bus and remain connected to the McDonald's access point blocks away. Of course, you can park your car in front of the McDonald's restaurant and remain connected to its Internet connection for as long as you wish.

So, to get fundamental, a land line from the Internet is connected to the access point maintained by the proprietor of a business, and the signal it is carrying is routed, wirelessly, to your computer.

That's pretty difficult when you're at 30,000 feet and traveling at 500 miles per hour. The nearest access point -- and it really isn't near -- is either approaching or disappearing second by second. So, how do we manage Wi-Fi from an airplane?

The airplane end of the connection is rather straightforward. Mount one or more access points in the airplane, and all travelers will have access to it (It's not as if you have to wonder about someone being a block away, and whether they can get proper reception). But how is the access point connected to the Internet? Two methods come to mind: a connection upward to a satellite, or a connection downward to a cellphone tower.

To be a little flip about it, downward seems closer -- until you are out over the Atlantic or Pacific oceans. But if we ignore that slight impediment, the approach is rather straightforward. The company that is most mentioned that solves the problem by using cellphone towers is Gogo.

Gogo owns more than 100 towers, covering the continental U.S. and parts of Alaska. The towers have been arranged to point their signals at the sky, rather than along the ground. An airplane picks up the signal through a receiver mounted on its underside. From there, of course, the signal goes to the cabin's access points. The administrative operations of signing in, providing passwords, paying for the service, and the like are left to the airline itself. Although the cellphone tower approach is Gogo's predominant approach, the company says it will deploy a satellite approach by 2014.

The other approach -- looking up -- is useable almost anywhere in the world. The company most mentioned is Row 44. The name itself has an interesting history. John Guidon, one of the company's co-founder, as a teenager was sitting in row 44 of a DC-10. The seat didn't recline, it was under an engine, in front of the galley, and adjacent to the lavatories. When working on an in-flight data service in later years, he and co-founder Gregg Fialcowitz decided that if they could make the passenger in Row 44 happy, they would have reached their goal.

Row 44's satellite-based uplink leases capacity from the existing HughesNet satellite Internet access system. The antenna is mounted on the roof of the airplane, (encased in a fiberglass RF-transparent radome) and all apparatus weighs in at about 150 pounds. The signal, as with the ground-based system, is then sent to the cabin's access points.

From an administrative standpoint certain features are always added. The FCC requires that the system can operate only at altitudes greater than 10,000 feet. So using the system while stuck on the tarmac simply won't work. Also, systems are designed to preclude voice. No one wants to listen at length to the guy who shares your armrest.

The system is not a pie in the sky scheme (pun intended). Airlines now involved (and each month getting more involved) are: American Airlines, Virgin America, Air Tran Airways, United Airlines, Air Canada, Alaska Airlines, US Airways, Delta, Southwest, and more.

Now we can say that from a communications standpoint every place on earth (and over earth) is equidistant from every other place.