A C-17 cargo aircraft piloted by Hickam Air Force Base commander Col. William J. Changose collided with a Hawai'i Air National Guard tanker aircraft about 200 miles off O'ahu during refueling training Thursday, officials said.

The collision sent the Air Guard KC-135R into a dive, causing some tense moments for its crew in the zero-gravity drop, but both planes landed safely.

The fuel-laden KC-135R received "minor" structural damage to its tail and refueling boom, said National Guard spokesman Maj. Chuck Anthony. The extent of the damage to the C-17, which was flown in from Oklahoma, was not available yesterday. Officials said the aircraft continues to fly.

There were some bumps and bruises among the Air Guard crew, but no decompression in the cabin, and no one required hospitalization, Anthony said.

A "safety investigation board" has been convened and will be chaired by the Hawai'i Air National Guard to look into the incident, said Maj. Paul Wright, chief of public affairs for the active-duty 15th Airlift Wing at Hickam.

Within about a week, Air Force investigators from outside the Hawai'i commands will arrive to examine what happened and whether proper procedure was followed. Those results will determine if action will be taken against the pilots, Wright said.

Changose and Brig. Gen. Peter S. Pawling, commander of the 154th Wing of the Hawai'i Air National Guard, are scheduled to pilot the first of the $200 million C-17s into Hickam on Feb. 8. Hawai'i is receiving eight of the aircraft.

The groundbreaking arrival represents the first time the Air Force's latest-generation cargo carriers will be stationed outside the Mainland. It also marks the first partnership with an Air National Guard unit to fly and maintain the aircraft, and is a shift at Hickam from a maintenance and mid-Pacific refueling hub to an airlift wing.

It remains unclear whether the C-17, coming up from below, flew too close to the tanker or the tanker flew too close to the cargo carrier. The refueling boom extending back and downward from the KC-135R telescopes from 28 feet 5 inches, to 47 feet 2 inches, Wright said.

The damaged refueling boom may have caused further damage to the tanker's tail, officials said. Wright said he could not positively say whether the two aircraft fuselages made contact.

"That's where the safety investigation board comes in," he said. "The refueling operation took place at night ... and there's probably speculation on the part of both the pilot of the 135 and the crew of the C-17 as to what happened. But the safety investigation board, they are the ones who take a look at both aircraft."

Changose, who commands the 15th Airlift Wing at Hickam, confirmed yesterday he was piloting the C-17.

"We brought a (C-17) back from Altus, Okla., so we could do some training over the holiday week," Changose said.

There were more than 100 passengers on the C-17, including dozens of Hawai'i Air National Guard members returning home for the holidays from training at Altus Air Force Base as Hickam prepares for the delivery of eight C-17 Globemaster IIIs beginning in February.

Changose said he was conducting flight instructor re-qualification when the 10:30 p.m. incident occurred. Twice before he was qualified as a C-17 instructor, he said.

"I was one of the first guys to even fly the thing," he said.

Changose, who holds the Distinguished Flying Cross, was a C-17 "initial cadre" pilot from 1993 to 1995, his biography states. He was a C-17 instructor aircraft commander in 1995 and 1996, a C-17 evaluator aircraft commander in 1996 and 1997, and a C-17 pilot in 2000 and 2001.

Changose said by regulation, "I have to wait until the safety investigation board is complete before I can talk" about Thursday's incident.

The four-engine C-17 is 174 feet long. The 136-foot-long KC-135R is the military version of the Boeing 707. C-17 pilots say in-flight refueling is a tense and delicate maneuver at slow speed and with two hulking aircraft at extremely close quarters.

Reach William Cole at wcole@honoluluadvertiser.com.