It's a general assumption that having your phone on in an airplane is no bigs, but we turn them off anyways. Apparently, pilots aren't following their own rules and are getting in trouble for it.

The FAA has issued an alert to airlines telling them to tell their pilots to turn their phones off.

The US FAA has issued an alert to airlines following an inspector's report that a first officer's cell phone began ringing at a critical phase of a takeoff recently, an incident the agency says was "a potentially serious hazard".

According to the FAA air safety inspector who was riding along on an unnamed airline's flight from the jump seat, just prior to reaching V1, the speed after which pilots generally are committed to taking off rather than aborting on the runway, a rather loud "warbling" sound was "detected" by both crewmembers.

"It was later determined that the sound came from the first officer's cellular phone, which had been left in the ON position," the Safety Alerts For Operators (SAFO) note reads.

"As a result the ring tone caused a distraction between the crewmembers during the takeoff phase and could have led the to crew to initiate an unnecessary rejected takeoff," the letter continues.

And even worse, he was totally being annoying and talking to his friends while other people were stuck in close quarters. How rude is that? [FlightGlobal]

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