Boeing said the aircraft was flown from Seattle to the U.S. Naval Air Station in Jacksonville, Fla., by Navy pilots.
The Navy has ordered 13 of the low-rate production aircraft although it intends a total acquisition of 117.
"We're proud to be able to meet our commitment and deliver another Poseidon to the fleet," said Chuck Dabundo, Boeing vice president and P-8 program manager. "Navy crews have had a couple of months of training with the first plane and their feedback has been positive."
Boeing said three P-8As -- for anti-submarine warfare, anti-surface warfare, intelligence, surveillance and reconnaissance -- are undergoing mission systems installation and checkout at its Seattle plant. Three others are in final assembly stages in Renton, Wash.
Production of the planes is in an in-line fashion -- all aircraft modifications are made in sequence during fabrication and assembly.
As part of the two LRIP contracts, Boeing is providing aircrew and maintenance training for the Navy, in addition to logistics support, spares, support equipment and tools.
Navy tests MQ-8C unmanned helos