Air Force colonels who aren't ready to retire at the 30-year mark can now volunteer to serve longer, leaders announced last week.

Fifty full-birds whose mandatory retirement dates fall between Feb. 1, 2018, and Feb. 1, 2019, have the chance to stay on active duty for an another three years, according to an Air Force news release announcing the change. Eligible officers must submit their records to the Line of the Air Force Colonel Continuation Board, which convenes this month. Colonels who qualify were notified at the end of 2017.

Col. Jeff O'Donnell, director of the Air Force Colonels Group, said the military needs the officers' expertise - especially as the service adds thousands of airmen to its ranks.

“It can take 21 years to develop a line officer to become a colonel who may then serve up to 30 years,” he said in the release. “We need experienced leaders to serve and lead across the Department of Defense.”

The Air Force has struggled to retain experienced officers, including in some high-demand fighter-pilot squadrons. In September, the Air Force had only 92 percent of its Line of the Air Force field-grade officers. Non-rated field-grade officers were manned at just 74 percent.

To help fill the gaps, captains up for promotion to major would have a 100 percent promotion opportunity starting in December. That means any captain with good conduct who was qualified and recommended for promotion can pin on a new rank.

"We've been letting capable people leave the service, and we need them," former Air Force Secretary Heather Wilson said last fall.

Aside from adjusting promotion rules, Air Force leaders are trying to improve the lives of airmen in order to retain the troops they need. Congress approved a request to boost pilots' retention bonuses from $25,000 to $35,000. Gen. David Goldfein told MOAA last summer that top leaders are also looking for ways to lessen the stress of high operational tempo and training requirements.

“We're doing a holistic review of the things we ask of our young force to ensure we allow them to find a work-life balance,” Goldfein said. “[We] are focused on building white space on the calendar wherever and whenever we can so our airmen can restore some balance in their lives.”