said by Corehhi :

This actually happened on a flight I was on. Capt. asked if anyone had a cellphone on or sat equiptment. 2 minutes latter he asked again and said it was screwing up the nav. system and they had to use a backup system. Then a guy jumped up from his seat and turned off a sat. phone he had. Capt. then got back on the speaker and said thanks interference was gone. This was a sat. phone though.

It was on a American airlines flying from Miami to the Cayman islands.