Amazon is hiring Sun Country Airlines to fly packages around the country, a windfall deal that thrusts the Minnesota carrier into the cargo business.

The six-year deal, announced Tuesday, will immediately create a massive expansion for Sun Country. From the first flights next spring, the new cargo service for Amazon Air will quickly grow to represent 20% of all of Sun Country’s flying.

It is the first time Amazon has hired a commercial passenger airline for air service.

Sun Country will add 10 airplanes to its fleet and hire an additional 70 pilots to its existing force of 350. The Twin Cities-based airline will also hire more maintenance workers and 20 to 30 headquarters staffers to support Amazon Air operations.

“These are pretty highly compensated positions. … We are very excited about this,” Jude Bricker, Sun Country’s chief executive, said Tuesday. “This is going to be a great growth opportunity for our company, and the important thing for the Twin Cities is it will make us a better airline for Minnesota leisure travelers.”

Sun Country has a history of running charter flights for sports teams, casinos and the military. And in the 1990s, the airline had a few short-term contracts with the Department of Defense and the now-defunct Gemini Air Cargo, but this is the first time it has pursued a major, long-term cargo contract.

The airline will acquire 10 Boeing 737-800 converted freighter aircraft beginning in April and will operate them on behalf of Amazon Air soon thereafter.

Seattle-based Amazon has been building up its air cargo fleet for the last three years, with the goal of having 70 leased airplanes by 2021.

Amazon currently contracts with cargo carriers, including Atlas Air, Southern Air and Air Transport Services Group. But it has expressed frustrations over protracted labor issues at those companies and threatened to pull its business.

Pilots at those airlines have also protested working conditions and don’t currently have a contract with their employers. They have attracted public sympathy, leading to some protests at Amazon shareholder events.

Bricker said these labor issues were never raised in his discussions with Amazon. “It never came up,” he said. “We only talked about ourselves and what we offer.”

Sun Country pilots are also represented by the Air Line Pilots Association, International (ALPA) and have a contract that gives the workers certain work rule guarantees and protections.

Bricker said all of its pilots will continue to be given 10 hours of rest between flights as they have for their commercial flights (cargo pilots only receive eight hours of rest). So, Bricker said, “We don’t expect it to feel any different for our pilots.”

Brian Lethert, a 19-year pilot for Sun Country and union chairman, said, “We are happy to hear about the growth and look forward to participating in the company’s plans.”

Sun Country did not pursue the business, but it came together quickly. Bricker had sent Amazon a note more than a year ago to see if the company was interested in buying some of Sun Country’s used equipment. He didn’t hear back until about four months ago with a different proposition: Do you want to fly for us instead?

Some Amazon Air executives flew out to visit Sun Country’s new headquarters at Minneapolis-St. Paul International Airport. They liked Sun Country’s nimbleness and experience operating the same type of used aircraft that Amazon flies.

“Sun Country has a proven track record flying 737-800 aircraft and a commitment to serving customers,” Sarah Rhoads, vice president of Amazon Global Air, said in a statement. “As we continue to grow our air cargo fleet on behalf of our customers to ensure fast, free delivery, we look forward to the ongoing partnership with Sun Country.”

The deal closed Saturday.

The airline is responsible for maintenance support, the flight crew, the FAA certificate and support security and dispatch, but won’t be loading and unloading the cargo.

The Federal Aviation Administration has different work rules for cargo pilots and commercial passenger pilots. Details of crew scheduling are still being arranged, but pilots will be based at MSP and fly all over the United States.

“They are looking for a really flexible operation and we can give them that with the way we schedule our service,” Bricker said. “From the pilots’ perspective, this will just be like scheduled service with plenty of advanced notice.”

Amazon has a reputation as being a bully with its contractors. Bricker said he isn’t concerned.

“We wouldn’t do it if it wasn’t a fair deal. We don’t need this flying, we want it,” he said. “Our core business is servicing the Minnesota leisure customer and we will continue to do that.”

Once the contract begins, Sun Country’s flying schedule will break down 20% for Amazon, 20% for charter flights and 60% for its bread-and-butter scheduled passenger service.

Sun Country does most of its maintenance at MSP, but doesn’t know yet where Amazon will want it to work on its airplanes.

Bricker does expect the planes — emblazoned with the light blue Amazon Air logo — to be flying through MSP “from time to time” for maintenance reasons. Amazon Air is currently building a $1.5 billion cargo hub at Cincinnati/Northern Kentucky International Airport where it hopes to house the fleet.

The 10 Amazon cargo planes will be in addition to Sun Country’s existing growth plans. The airline has about 30 airplanes with plans to add four to eight aircraft every year for the next several years.

The news comes a day after Amazon temporarily forbid its third-party sellers from using FedEx’s ground-shipping service for Prime members. Amazon and FedEx’s relationship has been rocky for several months.

FedEx ended its air-cargo partnership with the e-commerce giant in June and later suspended its ground-shipping contract. The tensions coincide with Amazon’s efforts to build its own logistics network, which includes the expansion of its own fleet of airplanes, trucks and vans.