Air Force squadrons at bases worldwide have begun retiring more than half of their C-21 fleets as part of a servicewide effort to cut personnel and save money.

The Air Force will transfer 38 aircraft, sending 16 from active-duty units to the Air National Guard in Fargo, N.D., and Bradley, Conn., the service announced in December. The rest of the jets will be sent to the Aerospace Maintenance and Regeneration Center at Davis Monthan Air Force Base, Ariz., and the Air Force Flight Standards Agency at Will Rogers Air Guard Station, Okla.

The C-21, the military’s version of the Learjet 35A business jet, is used mostly to transport senior-level officials, cargo and ambulatory patients. The twin turbofan engine aircraft, which first arrived in the Air Force in 1984, carries seven passengers.

The Air Force’s active-duty fleet had 74 C-21As, according to the service’s Web site. Each cost more than $3 million in 1996.

A final decision hasn’t been made about the four C-21s assigned to the 374th Airlift Wing at Yokota Air Base, Japan, according to Lt. Gen. Bruce Wright, U.S. Forces Japan and 5th Air Force commander.

“There will be a possible C-21 drawdown here,” he said Friday. “If we do it, it would be this year. Final notification may come this spring.”

The secretary of the Air Force approved retiring the planes as part of the service’s plans to slash 40,000 positions from its ranks to free money to buy new planes and modernize the force.

Trimming the C-21As from the active-duty inventory will affect 91 positions at Yokota; Keesler Air Force Base, Miss.; Wright-Patterson Air Force Base, Ohio; Scott Air Force Base, Ill.; Andrews Air Force Base, Md.; Peterson Air Force Base, Colo.; and Ramstein Air Base, Germany.

But Wright said he doesn’t anticipate a significant reduction in personnel at Yokota, where the aircraft’s maintenance is contracted to civilians. The C-12 could be tapped as a replacement if the base loses any of its C-21s, he added.

Yokota’s 459th Airlift Squadron conducts aeromedical evacuations and ferries senior officers and distinguished visitors around the Pacific.

“It’s a very important mission,” Wright said. “The C-12s would do a good job of backfilling if and when the C-21s leave. There’s a lot of water and distance in this part of the world. It’s important to have that transportation capability.”