By Andrea Shalal
WASHINGTON (Reuters) - Boeing Co and air crews from the U.S. Air Force completed the first refueling flight of the KC-46A Pegasus aerial tanker on Sunday, transferring 1,600 pounds (725.75 kg) of fuel to an F-16 fighter jet flying at 20,000 feet (6096 m), Boeing said.
The flight over Washington state lasted nearly six hours and marks a key step forward for the $49 billion program, which has seen cost increases and schedule delays in recent years.
Boeing, which has taken a total of $1.3 billion in pre-tax charges on the program to date, had hoped to carry out the first refueling flight last year.
Sunday's flight kicks off a series of aerial refueling demonstrations needed for the Pentagon to approve low-rate production of seven of the new 767-based planes, a decision expected later this year.
Colonel Christopher Coombs, who runs the program for the U.S. Air Force, called the flight an "important milestone" for the new jet in a statement released by Boeing early Monday, but he said there was "a lot of work yet to do."
The planes will be used to replace the existing fleet of KC-135 tankers, which extend the range of fighter jets and other warplanes by refueling them in mid-air.
Next, Boeing said, the KC-46A jet must show it can refuel other military aircraft, including a Boeing C-17 transport plane, a Boeing F/A-18 Super Hornet fighter jet, an A-10 Warthog ground attack plane, and the AV-8B Harrier jump jet.
The tanker used in the flight, EMD-2, has completed 32 flights since its first flight on Sept. 25, 2015.
Boeing said refueling operators from Boeing and the Air Force carried out multiple contacts between the KC-46A and the F-16 before fully extending the tanker's boom into its refueling receptacle.
“The boom was extremely stable – it handled like it was an extension of my arm,” said Rickey Kahler, a Boeing KC-46A air refueling operator, in a statement from Boeing late on Sunday.
Boeing is building four test aircraft under a 2011 Air Force contract to design and develop a multi-role tanker that can refuel all allied and coalition military aircraft and carry passengers, cargo and patients.
The contract calls for Boeing to deliver 18 tankers to the Air Force by August 2017, and build a total of 179 KC-46A tankers overall.
(Reporting by Andrea Shalal; Editing by Mark Potter)