Alaska Airlines has become the latest US airline to install in-flight WiFi onboard its fleet.

The airline launched the service in six aircraft May 18, promising to outfit its entire fleet with the technology by the end of 2010.

As an introductory offer, the inflight WiFi will be free of charge onboard until July 31, 2010 for customers to test the service.

After the free period, the cellular network-based service will charge from $4.95 per flight and up, based on length of flight and device used.

Alaska joined Southwest in rolling out onboard WiFi across its entire fleet, something that other US carriers such as Delta, United, AirTran and Virgin America are now embracing.

In Europe, however, inflight communications have been slower to take off - in March, budget carrier Ryanair was forced to put its inflight cellphone program on hold after only a year following problems with its telecommunications supplier.

Earlier this year, Oman Air became the first airline to offer mobile phone service and broadband internet on a long-haul flight.