For more than two decades, the C-130, the big, lumbering, beer-bellied military aircraft that crossed the skies above O'ahu's southern shore, has been the pride of the Hawai'i Air National Guard's 204th Airlift Squadron.

Various incarnations of C-130 Hercules have flown since the war in Vietnam, carrying everything from ground troops to armored vehicles into war zones and humanitarian sites around the world, and performing missions from combat support to chasing typhoons.

Since 1994, five Hercs — most of them minted within the past decade — made up the Air Guard fleet at Hickam Air Force Base. The first C-130 arrived in Hawai'i from Tennessee in 1984.

But this year the old turboprop-powered workhorses are leaving home, making room for a fleet of larger, faster jet-engine cargo planes: Eight brand-new C-17 Globemaster IIIs — which the Air Guard will share with the active-duty Air Force's 535th Airlift Squadron — are scheduled to arrive in February.

"We're losing a great airplane," said Lt. Col. Scott Kimsey, director of operations for the 204th and a longtime C-130 pilot who will retrain to fly C-17s. "The good news is we're getting another."

The switch to the C-17 is part of the Pentagon's efforts to make firepower in the Pacific more mobile and readily available, and with Guard units across the country losing their flying missions in the recent military cutbacks, the C-17 is a blessing. It holds the 204th together, and keeps it flying.

That doesn't mean there won't be culture shock. The Air Guard, with its older, more experienced airmen, some of whom have known each other since grade school and most of whom mix part-time military service with full-time civilian work, will become an "associate unit" of the Air Force's 535th Airlift Squadron, which has a younger, full-time, and more transitory force.

Guard units have traditionally valued their flexibility and autonomy. Active-duty units are more by-the-book military. Both sides are determined to make it work.

"It's a unique operation," said Maj. Paul Wright, an Air Force spokesman at Hickam, "the first of its type anywhere in the Air Force.

"We'll have some problems, but the Guard and active duty have worked together a lot in recent years, and that is what has convinced us we can make it work."

No one in the Air Guard unit denies that the C-17 is an impressive aircraft. It may require a slightly longer and wider patch of dirt to land on compared to the C-130, but the difference is negligible, and the C-17 can carry nearly four times the gross weight of cargo that a loadmaster can cram into a C-130.

It may not be the most popular military cargo plane in the world — the C-130 has had a much longer career in which to develop that title — but the C-17 can fly to its destination with half the cockpit crew.

With four jet engines instead of four turboprops, the C-17 cruises at 675 mph, compared to the 410 mph that a lightly loaded C-130 might manage with a favorable tail wind.

The newer airplane also has it over the old one in range. The C-17 can be refueled by tanker aircraft in midair, making it capable of circling the globe. The C-130 must land to refuel every 3,000 miles or so.

But none of that changes the likelihood that while the Hawai'i Air National Guard may welcome the C-17 mission, they're going to miss the C-130.

Tail No. 1058 is the only C-130 that still sits on the flight line at Hickam, a little lonelier as the airmen of the 204th spend more of their time on the Mainland, training to fly or maintain the C-17s.

It is scheduled to stay until early next year, on hand for civil defense emergencies until the arrival of the first C-17, fresh off the factory line at Boeing and due in February.

C-130s like No. 1058 flew five supply runs daily to residents of Kaua'i after Hurricane Iniki struck in 1992. They've been in typhoon relief missions in Guam, flown fire equipment to Moloka'i, and conducted medical evacuation missions in Johnston, Wake and Kwajalein.

"This is my seat," Tech. Sgt. Les Hirano said as he climbed into the cockpit during a recent tour of the last C-130 and, moving with a confidence born of habit, lowered himself into the flight engineer's seat, high and centered behind the pilot and copilot, to the left of the navigator's position.

He barely made contact with the sheepskin seat before jumping back up.

Hirano, who works as a housing inspector in his civilian job with the city, is not a flight engineer anymore. Flight engineers, like navigators, are being made obsolete by the C-17s.

"I've been avoiding the cockpit of this airplane for a while now," Hirano said. "Kind of sad."

The military has retrained Hirano to be a C-17 loadmaster. He'll continue to fly, but in the cargo area, not the cockpit.

Lt. Col. Tim Fujino, formerly a C-130 navigator, will be the Guard's C-17 maintenance officer. He is no longer a flight crew member. He's grounded.

Some of the C-130 pilots retired. Others, like Kimsey, are retraining to fly the new aircraft.

Kimsey said he will miss the camaraderie that comes from flying with the large, tightly knit C-130 crew.

He'll also miss the independence that went along with the C-130. With its slower speeds, lower costs and the necessity for frequent fuel stops, the older airplane often "slipped under the radar," of the military, he said, allowing the crew a greater degree of autonomy than they will see on the C-17.

On the newer airplane, every flying hour will be closely accounted. Each Guard mission will be weighed against those of the active-duty forces, with the most essential winning out.

"The C-130 has more of a bush pilot feel to it," Kimsey said.

"Sometimes, it is the journey, not the destination, you remember."

Reach Karen Blakeman at kblakeman@honoluluadvertiser.com.