"Boeing — the prime contractor — plans to deliver the first 18 fully capable aircraft to the Air Force by October 2018, 14 months later than initially planned. Potential delays in completing flight tests may further delay the delivery of aircraft," the report stated.
The GAO report attributed delays thus far to FAA certification of air refueling pods and postponements of test flights.
Despite falling behind schedule, the KC-46 modernization program is meeting cost and performance targets, the report said.
Total costs have decreased about $7.3 billion, or 14 percent, in the program, which is intended to provide replacements for about one third of the US fuel tanker fleet, the report noted.