While we sit facing the tarmac — the second busiest single airport runway in the world, after London's Gatwick — a news van glides past. “They must be out here for the Malaysian thing,” says Coates, before turning to me. “Did you hear about the Malaysian that went down?” It’s July 18, 2014, the day that news breaks of MH17’s wreckage being scattered across the Ukrainian countryside. Amundsen reveals that he has flown on that destroyed Malaysia Airlines plane, while Coates has flown on MH370, the one that went missing in March. They know this because they both keep records of every flight they’ve ever taken.

“We’re pretty serious about it,” Amundsen continues. “At home, Simon and I have got ADS-B receivers; with those, on our computer screens at home, we can virtually see exactly what the air traffic controllers can see. If something unusual pops up on our radar screen, that’ll usually give us half an hour to get out here and catch it.” (Neither of them can recall what ADS-B stands for, so Coates googles it: Automatic Dependent Surveillance — Broadcast.) A plane-tracking website named FlightRadar24 feeds off these receivers. Coates opens the app on his phone, which shows a bunch of tiny yellow icons overlaid on a map. “You can see all the planes buzzing around," he says.

“This app runs off people’s home feeds,” Admundsen explains.

We meet at what’s known as "The Loop" — one end of Acacia Street, which borders Brisbane Airport and offers the best runway-side sight lines for spotters, including a raised concrete viewing platform. At age 15, Amundsen began learning to fly at flight school; a year later, he was flying a skydiving plane for fun and profit, and by 19 he had obtained his commercial pilot license. He has clocked over 3,000 hours in the cockpits of airplanes and helicopters. Coates is employed by the Qantas Group too, as a ground handling agent here at Brisbane Airport — a job that, he says with a smile, involves “passenger marshaling, boarding flights, standing out on the apron, getting high on aviation fuel every day.” He jokes that he has logged over 800 “backseat hours” on commercial flights.

Through the windshield, we watch a red-tailed Boeing 747 take off. “See, there we go, he’s off to Singapore,” says Amundsen, pointing. “He’s up nice and early.”

“Very early variation,” says Coates, admiring the steep ascent.

“That’s, like, a QF8 rotation. He’s got awesome headwind. The wind’s coming from the south, and going over the wing.”

They know the Qantas jet is heading to Singapore because it ascended so sharply. “There’s two [Qantas] 747s,” says Amundsen. “One goes to L.A., one goes to Singapore. The L.A. one goes out a hell of a lot heavier; it would have over 100 tons of fuel on board. That would only have about 60,” he says, pointing again at the now-distant aircraft, growing smaller by the second.

Amundsen knows these routes and schedules particularly well, as he lives nearby. “If I could live closer, I would,” he says. "I can be lying in bed at midnight and hear the Emirates 777 come over, and know exactly what it is, straightaway. I don’t even have to look up.”

Amundsen’s comment about the presidential plane arises as the pair discuss the upcoming G20 summit in November. These two will be among the crowd attempting to gather somewhere near this airport, cameras in hand, searching the skies for Air Force One in the hope of capturing a once-in-a-lifetime event: the president of the United States of America landing at their home airport. An intense Australian Federal Police presence surrounding the miles of wire fences day and night for the duration of the summit mean that shooting Air Force One is an unlikely event indeed. But still, the possibility is there.

And possibility is what drives planespotters — otherwise known as “jetrosexuals,” “aerosexuals,” and “cloud bunnies” — a niche group of obsessives whose intense interest in flight paths, travel schedules, and colorful jet livery occasionally overlaps with the concerns of the general population.

When Malaysian Airlines Flight MH370 vanished on March 8, 2014, planespotting had its best chance at making a mainstream impact. While millions combed satellite images online to look for signs of wreckage, a 32-year old designer and filmmaker based in Jersey City, New Jersey, named Michael Raisch had a different approach: to collaborate with global planespotters and create a visual tribute to the aircraft. Raisch searched MH370’s tail number — 9M-MRO — and emailed around 80 spotters who had photographed the plane. Raisch says, “I had the simple thought, ‘You captured this little thing that’s gone, it’s not coming back, no one can take this picture again — how do you feel?’”

Ultimately, 22 spotters from around the world replied and offered Raisch shots they had taken from 2004 to February 2014. His tribute functioned as a kind of eulogy for the physical aircraft, and it struck a chord, attracting 120,000 visitors in the month after its publication on March 30. “The planespotters gave us a human connection to this missing plane, and I think that’s why it went viral,” Raisch says.

To seasoned sky spies like Amundsen and Coates, such headlines are viewed as sideline attractions rather than the main event. Rather than chasing the loudest sirens and smoldering wreckage, theirs is a process of passion — they show up day after day, week after week, and cast their eyes toward the runway. But since September 2001, any pastime involving the close scrutiny of commercial aircraft cannot be seen as wholly innocent.

In front of our parked car are a father and son, lying in the back of their four-wheel drive to escape the wind, doing exactly the same thing as we are. Later, Amundsen says, “I just broke up with my missus, mate. That’s a good thing, you know? I reckon spotting was more important than her!”

Coates cackles. “Amen to that!”