Helix became Project Airseeker, under which three KC-135R airframes were converted to RC-135W standard by L-3 Communications. L-3 also provides ongoing maintenance and upgrades under a long-term agreement. The three airframes are former United States Air Force KC-135Rs, all of which first flew in 1964 but were modified to the latest RC-135W standard before delivery. The three airframes on offer to the UK are the youngest KC-135s in the USAF fleet. As of September 2010 the aircraft had approximately 23,200 flying hours, 22,200 hours and 23,200 hours.