You knew this was coming.

Bloomberg News is reporting that flight attendants at American are asking the carrier to put filters on its in-flight Web service to block out porn and other sites they say are inappropriate.

Union leaders at American say they’ve met with management on the problem but haven’t made a formal request yet. American launched a trial of inflight WiFi on Aug. 20 on 25 daily flights between JFK and LA or San Francisco, and between New York and Miami. The charge for the service is $12.95.

“We have brought the issue to management’s attention since we’ve heard a lot of complaints from flight attendants and passengers about the issue,” David Roscow, spokesman for the Association of Professional Flight Attendants, told Bloomberg.

This is just the beginning for this issue. Last year, several airlines announced that they were looking to offer inflight Internet service. Currently JetBlue provides limited access on one plane. Southwest and Delta plan to offers service by late 2008 and 2009, respectively.

The airlines see it as a competitive issue. They believe Web access is something that travelers want. And analysts have noted that the introduction of WiFi could also allow carriers to get rid of some or all of the music and video equipment they carry, trimming maintenance costs and making planes lighter, which would yield savings in fuel costs.