Two Boeing T-X trainer aircraft fly over the St. Louis Gateway Arch. The Air Force announced Thursday that it has selected Boeing's offering to replace its T-38 Trainer aircraft, which has been in service more than 50 years (Photo by John Parker) (E.Shindelbower)

Boeing has been award­ed a $9.2 billion con­tract to build the Air Force’s next fleet of com­bat train­ing aircraft, the Defense Department an­nounced Thurs­day, lock­ing the Chicago-based aer­o­space com­pany into the larg­est U.S. mil­i­tar­y aircraft pro­cure­ment in years.

The serv­ice plans to buy a­bout 350 of Boeing’s T-X aircraft to re­place its T-38C Tal­ons, which have been in serv­ice for 57 years. The con­tract calls for the plane to be ready for full operational deployment by 2034.

In a statement, Air Force secretary Heather Wilson touted the cost savings achieved through the award, noting that initial estimates had pegged the cost of the program at almost $20 billion. All of three of the major contenders for the award had incorporated international partners into the design, with Swedish, Italian and Korean joint ventures vying for the opportunity.

"This new aircraft will pro­vide the ad­vanced train­ing ca­pa­bil­i­ties we need to in­crease the le­thal­i­ty and ef­fec­tive­ness of fu­ture Air Force pil­ots,” Wilson wrote. “Through com­pe­ti­tion we will save at least $10 billion on the T-X pro­gram.”

For Boeing’s Arlington-based defense busi­ness, the a­ward caps off a stun­ning win­ning streak.

While Boeing re­mains a leader in com­mer­cial aircraft, it has been out­flanked by ri­vals re­cent­ly in the defense market. Lock­heed, the man­u­fac­tur­er of the F-35 Joint Strike Fight­er, is the world’s larg­est defense con­trac­tor by a wide mar­gin, tak­ing in $50 billion in U.S. con­tract dol­lars last year com­pared with Boeing’s $23 billion. Investors saw Boeing’s loss to Northrop Grumman for the opportunity to build the B-21 bomber in 2015 as a major setback.

But Boeing has notched a string of victories in the past month, winning footholds on major military programs that should pad its coffers for decades. In late Au­gust, the company was award­ed an $805 million foot­hold in a pro­gram to build the Navy’s MQ-25 a next-generation drone desiged to refuel fighter jets in mid-air. Then, this week, it won a $2.4 billion con­tract to re­place the Air Force’s ag­ing UH-1N heli­cop­ters.

Boeing was the only competitor to design a plane from scratch, teaming with the Swedish manufacturer Saab on the project. That approach may have raised the stakes somewhat: if the Air Force had gone with another company’s plane, Boeing would have sunk millions of its own research and development capital into the project to little reward.

With Thursday’s win, the company’s executives can breathe a sigh of relief.

“Today’s an­nounce­ment is the cul­mi­na­tion of years of un­waver­ing fo­cus by the Boeing and Saab team,” Le­anne Caret, chief ex­ec­u­tive of Boeing’s defense unit, said in a state­ment. Caret took over the company’s defense business in 2016 as part of a broader reorganization designed to streamline the company’s operations, cutting out layers of upper management.

The T-X contract win“is a di­rect re­sult of our joint in­vest­ment in de­vel­op­ing a sys­tem centered on the unique re­quire­ments of the U.S. Air Force. We ex­pect T-X to be a fran­chise pro­gram for much of this cen­tu­ry," she wrote.

The other major contenders had both pitched modified versions of older planes.

Lock­heed Mar­tin and Korea Aer­o­space Industries had teamed up to of­fer the T-50A, which has already been used to train pil­ots in Korea, In­do­ne­sia, Thai­land, the Philippines and Iraq. And Leonardo DRS, a U.S. sub­sid­iary of an I­tal­ian defense man­u­fac­tur­er, of­fered a modi­fied ver­sion of one of its old­er train­er mod­els called the T-100.

“We were disappointed to learn that the U.S. Air Force did not select our offering,” a Lockheed Martin spokesman said in a statement Thursday. “We believe we presented a very strong solution and await the customer’s debrief to hear more details regarding the decision.”

Analysts were skeptical that the Air Force will actually save $10 billion through the award. Estimates of the program’s total cost have ranged between $16 million and $19 million, meaning Boeing agreed to build the plane for about half of what had originally been expected for the project.

Such a substantial cost-savings is almost unheard of in military procurement, suggesting the program could eventually be subject to cost overruns. Others worried about which capabilities the Air Force dropped by bidding the price so low.

“When a military service says they saved $10 billion you have to wonder what they took off the aircraft,” said Loren Thompson, an analyst with the Boeing-funded Lexington Institute.

The Air Force’s move to re­place the ag­ing train­er aircraft is long-await­ed. The new planes are to re­place the T-38C Talon, which was de­vel­oped by North­rop Grum­man more than half a cen­tu­ry ago.

The program was first conceived in policy documents dating back to 2009, but a request for proposals wasn’t issued until 2016. A 2016 study found only 60 percent of the Air Force’s existing T-38 fleet to be “mission-capable,” complicating the service’s efforts to mend a persistent pilot shortage.

Dave Deptula, a retired Air Force general who is dean of the Mitchell Institute for Aerospace studies, called the T-38 a “a great poster child for the geriatric Air Force we now have,” arguing the T-X contract should have been bid out long ago.

“This a­ward is a­bout 30 years o­ver­due,” he said. “It’s amaz­ing that more of those T-38s aren’t fall­ing out of the sky.”

Richard Aboulafia, an analyst with the Aerospace consultancy Teal Group, said the T-X could be the “last training aircraft of its kind,” noting that remotely-piloted drones could replace piloted planes by the time the Air Force orders another model.

“If the T-38 story provides any guidance, the last T-Xs could still be in service in 2090,” Aboulafia wrote in a recent Forbes blog.