From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
"Krypter" is one Colonial equivalent of the "mayday" distress call.
In the Miniseries, Captain Lee Adama loses power to his Viper Mark II after he lures away and destroys a Cylon missile inbound for the civilian transport Colonial Heavy 798. The blast of the missile that he shoots down strikes Lee's Viper and damages his power systems or other avionics needed for navigation.
Adama sends out a mayday call to Colonial Heavy 798 prefixed by, "Krypter, krypter, krypter..." (Miniseries).