It’s Buffalo’s busiest winter yet, and they roll out the C-46, TXW, to fly all the freight up the Mackenzie Valley. But when one of TXW’s engines catches fire, Buffalo scrambles to find a backup plane in time for Christmas deliveries. They look to their newly purchased Electra, XFC, to fill the void, but Adam, Chuck, Brian and Mikey discover it has a cracked windshield and cannot be flown safely. Joe, Brian and Cory fly to meet Rod in Red Deer to grab a replacement windshield. When they arrive, Joe first reveals his other plans—he wants the second Electra ZFE dug out of the snowbank where it’s been sitting for months and get it up and running so that it can replace XFC on the Valley run. Rod’s upset that he wasn’t given more notice, and unloads on Mikey about Joe’s reactionary management style. Back in Yellowknife, Buffalo’s newest rampie, Prefkar Mony, is a determined young pilot from India who’s got his eyes on flying Joe’s prize planes. But first he has to adjust to life in the North—and purchasing proper winter gear is the first thing on his list

Chief Pilot AJ Decoste is flying up the Mackenzie Valley with Buffalo’s newest Electra, XFC, for the first time. Mechanic Cory Dodd is along for the ride to do some training as a Flight Engineer. They try to make their deliveries before a storm rolls in but when they land in Norman Wells, they are faced with gale force winds. When their takeoff is delayed by two incoming planes, AJ is forced to shut down and wait out the storm in Norman Wells. Later, on their approach to Tulita, they face even stronger winds gusting over 40 knots. Over in Hay River, things go from bad to worse when a warm weather system brings the threat of a rare ice storm. Two daily skeds arrive from Yellowknife and the rampies have to batten down the DC-3s in preparation for a long, rough night—the worst storm in fifty years. And the newest rampie, CJ Asaf, just can’t seem to fit in. Rampie Prefkar is tasked with training CJ on the Hay River delivery route, but Prefkar can’t handle CJ or his attitude.

When Buffalo’s newest Electra, ZFE, lands in Yellowknife with only three functioning engines, mechanic Chuck Adams comes to the rescue to replace a brand-new $29,000 regulator on engine number three. It’s been slow for the airline and delivering a load of building supplies to the RCMP up in Ulukhaktok, NWT, might help keep Buffalo in the air. Spurred by a recent crash landing and two engine fires, an audit team from Transport Canada descends on Buffalo Airways. With their long and tumultuous history with Joe, they demand that Buffalo appoint a new “Accountable Executive” within 72 hours, or risk being shut down. But Joe isn’t about to hand over the keys to the kingdom—not even to Rod, his oldest son. Mikey worries that if they don’t meet the deadline, Buffalo Airways could become Buffalo Spare Parts. Transport Canada isn’t the only thing on Joe’s mind; it’s becoming apparent that Joe’s 16-year-old rescue dog, Sophie, is on her last legs. One morning Joe finds Sophie lying under a plane, unable to stand up. Joe realizes that her time has come—he calls the vet.

Buffalo Joe has been a captain on the daily sked for 34 years and his 70th birthday is next week. Joe might have to stop flying if he doesn’t pass his medical and that could spell the end of Buffalo. Before Joe leaves to undergo five days of medical tests at the Mayo Clinic in Phoenix, Arizona, he calls two rampies, Sam Storm and Jeff Tapper, into his office to greenlight their DC-3 checkflights. Both Jeff and Sam have slogged away for eight months waiting for this chance. But on flight day, Sam is sick to his stomach from eating bad eggs the night before. Sam is not about to let a bad egg beat him and he helps Jeff prep DC-3, LFR. Just before takeoff, nausea wins—Sam has no choice but to back out and there’s no telling when he’ll get another chance. Jeff, on the other hand, has to overcome the jitters that have haunted him ever since he was in a crash landing earlier in the year. Mikey, Rod and his family prepare to greet Joe with a birthday cake shaped like a DC-3. At the last minute, Mikey gets a call that Joe isn’t coming back today; instead he’s decided to celebrate his own way—going for a ride in a classic 1940 Boeing Stearman biplane.

Newly minted copilot Jeff Tapper is excited for his first revenue DC-3, but his inexperience shows when he botches the approach and bounces the landing three times, nearly running off the runway. Meanwhile, for new rampie Prefkar Mony to realize his dream of becoming a DC-3 pilot, he needs to first pass the written IATRA test. He’s been studying for months, but on his first attempt, he fails. With the help of pilot/mechanic Chris Staples, Prefkar retakes the test and passes, but his victory celebration is short-lived when he’s blamed for leaving an expensive shipment of medicine marked “Do Not Freeze” in a courier van during a minus 30 weekend. Later, Mikey and Katie decide to find Joe a new dog and choose Muffy, a three-year-old dog from the SPCA who is ready to leave her pups. They bring her back to the hangar for a test drive. Joe brings DC-3 CUE out of retirement to test fly the plane for Buffalo’s summer sked duty and he brings along Jeff—and Muffy—to see if they’re Buffalo material.

Mikey talks to a 15-year-old aviation buff in England via Skype, who has discovered that Buffalo’s DC3–WZS–flew on D-Day. This inspires Mikey to do something special for the 70th anniversary. He invites Cory to do a tandem parachute jump and finds out that Cory’s grandfather was a paratrooper at the invasion of Normandy. Meanwhile, Mikey takes mercy on Prefkar, working the ramp in Hay River, and offers him a chance for some pilot training on the morning DC-3 freighter. But when the time comes, Prefkar learns that he’s been bumped for pilot David Alexandre. It gets worse for Prefkar when he’s given another chance and this time the fog rolls in. Prefkar might not stick it out at Buffalo. Mikey’s D-Day plans get even bigger when he contacts the Princess Patricia Canadian Light Infantry, who were part of the Allied airborne forces that dropped behind German lines in 1944. He pitches his plan—a reenactment jump from WZS, an actual D-Day plane. But there’s a hitch: the plane needs to pass inspection, and Mikey needs to lose weight to make the cut for tandem jumping. Mikey tries everything he can think of—from juicing, working out with Dan at the gym and even sweating it out in spin class. Cory and Mikey go over what they need to refit DC-3 WZS for a static line jump. Cory is sent on a scavenger hunt for parts in Red Deer and finds a brand-new bracket from the 1940s—but they still need to find the missing rear bracket, and nobody even knows what it looks like.

Mikey shows a veteran Buffalo’s DC-3, WZS, Buffalo’s very own vintage plane from the Second World War. It is being fitted with a special ‘static’ line, which paratroopers will clip onto for a D-Day reenactment jump. But army inspectors tell Mikey a modern military needs a modern line with a winch system in case they need to retrieve a “hung-up jumper”. Cory and Mikey scramble to build the retrieval line before the inspector comes back to test it. But with their bumbling and fumbling, it doesn’t look like they will make the cut. Meanwhile, Chris Staples and some of Buffalo’s pilots head down to Fullerton, California, to Air Combat USA, where pilots get to experience aerial dogfights in real fighter planes. The pilots do yo-yos, spins and pull Gs to out-maneuver their opponent. First up in the dogfights are newly checked-out co-pilot Sam Storm versus longtime co-pilot David Alexandre. Sam wins the fight due to David’s inability to hold down his breakfast. Next up is cocky co-pilot Chris Staples versus his C-46 captain Devan Brooks. But Devan’s many years in DC-3s and C-46s have left him unprepared for the video game pace of dogfighting and he quickly loses 3-0. Finally, the two top guns return to the sky. Sam scores first, but Chris is not about to get beaten.

The Buffalo boys gather in Red Deer for Mikey’s D-Day tribute jump. Joe and Sam scout out the designated military drop zone over Abraham Lake in the Rockies only to discover the canyon is too narrow for the DC-3. So Joe cancels the whole thing—it’s too dangerous. Mikey uses Joe’s own philosophy against him: at Buffalo, there’s always a backup plan. Joe flies out to scout a new location for the drop on the lake but hits bad weather. As Joe is about to scrap the trip, twenty paratroopers from the Canadian and American armies arrive for the big jump and are ready to go. They board WZS and Joe takes off to a site he hasn’t scouted, in weather that just keeps getting worse. As they near the drop point, he finally calls it—no jump tonight. They turn back, with all the troops still on board. Mikey’s only hope is a narrow window first thing the next morning—but only if Joe gives the final okay.