Newsbeat US reporter
American Airlines is among the first to provide wireless access on its planes
It could be the ideal way to get through a long aeroplane journey - messaging friends on Facebook, downloading music, even watching streaming video clips.
A growing number of airlines are allowing passengers to go online while they fly.
However, as often happens with new technology, there's disagreement over the best way to provide internet access at 35,000ft (10,668m).
While the United States is opting for low cost, on board Wi-Fi hotspots, European airlines are encouraging their passengers to connect using more expensive mobile phone systems.
In the US, American Airlines is among the first to provide wireless access on its planes.
Passengers flying from New York JFK to Miami, Los Angeles and San Francisco can log-on, for a flat-rate of $12.95 (£9).
Its Gogo service is provided by US-based Aircell.
The company uses a network of ground-based antennae to keep planes connected to the internet.
Passengers are allowed to use laptops and handheld devices
Aircell CEO Jack Blumenstein explained: "You think of a mobile phone network. Instead of the towers pointed down at the ground, you've got towers pointed up in the air, providing seamless coverage across the country.
"With the use of off the shelf wireless technology, we took a huge bite out of the cost and you can translate that into an attractive cost to the passenger," he added.
Gogo allows full internet access, but Voice Over Internet Protocol (VOIP) calls, using software such as Skype are banned.
Another provider, Row 44, has been signed up by Alaska Airlines and Southwest Airlines.
Row 44's planes connect to the internet via satellite, with a transmitter/receiver mounted on top of the aircraft.
Inside the cabin, both companies use industry-standard Wi-Fi connections, allowing passengers with laptops and handheld devices to go online.
The technology has been deemed safe because the frequencies it operates on do not interfere with aircraft navigation systems.
However, the US Federal Aviation Authority is refusing to allow passenger use of mobile phones.
"An airline would have to prove to the FAA that there was no chance of electronic interference with aircraft instrumentation," said FAA spokesperson Alison Duquette.
"To date, that has not been done with cell phones."
The picture in Europe is very different.
Safety regulators there have approved the use of mobile phones on certain planes.
Airlines, including BA, BMI and Ryanair are running trials.
There were not usage rates among passengers that would justify further investment
Passengers' handsets pick up a signal from miniature aerials, known as Picocells, similar to those found in full size phone masts.
These flying base stations, in turn, connect to the regular phone networks by satellite.
As well as allowing voice calls, travellers with laptop data cards or internet enabled mobile phones can go online.
However, prices are likely to be substantially higher than the US Wi-Fi system.
Data tariffs are still being worked out, but are expected to be in line with the £1.70-£2.00/minute cost of voice calls.
The main European provider of in-air phone systems is Switzerland-based OnAir.
The company has asked the European Union to exempt in-flight telephone calls from legislation that would force down prices for mobile roaming on the ground.
It claims enforcing price caps could damage the growth of aeroplane data use.
There is nothing to stop European airlines opting for a US-style hotspot system, however the European Aviation Safety Agency (EASA), which would have to approve the technology, says it has not been asked to certify any WiFi installations.
Despite the potentially high usage costs, both European and US providers of in-plane internet say they are confident that there is customer demand for their services.
Similar ventures have tried and failed in the past.
In 2001, Boeing launched Connexion, an on-board WiFi service that offered high-speed internet access via satellite link.
The service was available on British Airways and Lufthansa.
It was widely praised for its reliable, high-speed connection.
However Connexion was discontinued in 2006.
Boeing spokesman John Dern told BBC News: "There were not usage rates among passengers that would justify further investment.
"We were only seeing in the high single digits in terms of passengers using it."