In a voice that is preternaturally calm, Captain Chesley B “Sully” Sullenberger III is talking to me about turbulence. Members of the public, he says, often tell him how much turbulence perturbs them, and though he doesn’t remotely share their anxiety, he understands it perfectly. In the sky, after all, we cede control of our future to someone who is unknown to us. Most people, moreover, know very little about the construction of aircraft, much less the endlessly rehearsed systems that keep them above the clouds; we understand aerodynamics not at all. So when the long metal tube in which we are travelling begins to bob and buck, no wonder our hearts beat a little faster, our palms grow hot and sticky. We are human and we panic, even if some of us try very hard indeed not to show the extent of our fear to the man in the aisle seat who is reading Time magazine so nonchalantly.

Across the coffee table – we are in a suite at Claridge’s in west London, where the art deco furniture is a rather appropriate shade of air force blue – Sullenberger meets my eye and holds it. “Now,” he says. “I have some specific advice about turbulence and how you might reframe your thinking about it.” A brief pause. “Next time you’re a passenger in an automobile, I want you to close your eyes and really concentrate on every bump and jolt in the road. I want you to catalogue them and then to imagine that you are also trying to read or to eat a meal.” Another pause. “It would be difficult. The reality is that the average car trip is much rougher than almost any flight. But the difference is that the driver is known to us and it’s familiar: we understand how cars work.” His voice rises a notch, in the manner of a motivational speaker. “Airplanes are designed to handle the worst turbulence, plus a safety margin of 50%, and pilots are trained to avoid it when they can and to manage it by changing speed and altitude. They are going to take care of you. The airplane is not going to come apart. This is just a temporary inconvenience.” Am I soothed? Yes. In this mode, he’s mesmeric. But it’s hard not to laugh, too. If only director Clint Eastwood had had the wit to call his new movie about Sullenberger This Is Just a Temporary Inconvenience.

Sullenberger is the pilot who, on 15 January 2009, successfully landed his Airbus 320 in the Hudson river, New York, saving the lives of all 155 passengers and crew after the aircraft struck a flock of birds, putting both engines out of action, shortly after its take-off from LaGuardia airport. Naturally, the film inspired by his story, Sully, does its best to point up his extraordinary valour on that day; this is the guy who, after all, walked up and down a rapidly sinking plane not once but twice in an effort to make sure no one remained on board before he cut the life rafts loose. But the man at its heart, on screen as in real life – Sullenberger is played by (who else?) Tom Hanks – is a stubbornly old-fashioned kind of a hero, distinctly minimalist in the matter of public displays of emotion; basically, he’s John Wayne with a mobile phone and a carry-on bag. Ask him, for instance, what he really said to first officer Jeff Skiles in the moments after the plane hit the deathly cold water – surely the movie’s screenwriter exaggerated his composure just a little – and without missing a beat he’ll reply: “It wasn’t as bad as we thought.” (The last time I heard these words, it was Hanks who was saying them and I was fanning myself with a copy of the Evening Standard and trying not to pass out.)

Facebook Twitter Pinterest Aaron Eckhart and Tom Hanks in Clint Eastwood’s film Sully. Photograph: Warner Bros

What is it like, revisiting these events on screen? Sullenberger and his wife and two daughters first saw the film at a studio in California last July. “It was an emotional moment,” he says, sounding neither shaken nor stirred. “It took us several hours to process it, to put it into words. We saw it in Burbank, and then we flew back to San Francisco, and when we were home having dinner, my younger daughter said, after some period of silence: are we going to talk about this or what? So we did. We had the most wonderful, touching and, in some cases, humorous discussion about it.”

Is it accurate? “Yes. Everyone worked hard to get it right. The granularity was amazing to me. They wanted to know: what are your rings like? What kind of watch do you wear? When you sit down in the cockpit do you take off your jacket and loosen your tie? I even had Clint, Tom and Aaron [Eckhart, who plays Skiles] in a flight simulator with me to familiarise themselves with the dynamic of the cockpit. The flying sequence in the film is very realistic.”

Though partly based on it, the film takes the story further than Sullenberger’s 2009 memoir, Highest Duty, a book that was published before the National Transportation Safety Board (NTSB) – the agency charged by the US Congress with investigating air accidents – completed its investigation into the crash, a process that in reality took some 15 months, but in the film appears to last only a matter of days.

Immediately after the accident, Sullenberger was widely hailed as a hero by the media, for which reason I, like most people, had never thought he could possibly be seen in any other light. Behind the scenes, however, machinery was turning. In spite of the seeming miracle on the Hudson, he would have to wait to be vindicated for the decision he made that day. He had saved lives, but he had lost a plane. The investigators believed their simulations might show that he could have made it back to LaGuardia; they also believed, for a while, that only one of the plane’s engines had ceased to function.

How nervous was he about the investigation? “Initially, very nervous. First of all, the trauma of the event was so intense. We all suffered from PTSD [post-traumatic stress disorder]. My pulse and my blood pressure were highly elevated for several months and at first I could only sleep for 30 minutes at a time. Added to the uncertainty of the investigation and the possible threat to my professional reputation, it was a very difficult period. But we had to have what I call realistic optimism, [to hold on to the idea] that we would prevail.”

While the various bodies involved, among them US Airways, the airline for which Sullenberger worked; Airbus, the manufacturer of the aircraft; and the Federal Aviation Administration (FAA), the body responsible for regulating civil aviation in the US, protected their own interests, the US Airline Pilots Association worked tirelessly on his behalf. “The investigators from the NTSB were not there to be on my side. Their purpose is to be on the side of truth and fact. They were going to follow that wherever it led. Our professional reputations were expendable. I was just an individual. I am sure they would have thrown me under the bus if necessary.”

Facebook Twitter Pinterest Passengers stand on the wings of the US Airways plane after it ditched in the Hudson. Photograph: Brendan McDermid/Reuters

Ultimately, the test pilots, who, in a simulated reconstruction of events, had managed to take the failing plane back to LaGuardia, were revealed to have practised the manoeuvre multiple times. Once this was known, Sullenberger’s reaction times, born of an unpreparedness quite different from theirs, had only to be factored in for their models to fall apart and the plane to crash in the next simulation. The investigators concluded that he had, after all, made the right decision.

On the page, though, this perhaps makes it seem as if Sullenberger had a period in which to think, to weigh up his options, which he certainly didn’t. Look at the transcripts of the conversations between the cockpit of US Airways flight 1549 and air traffic control on that fateful day and you’ll see – the heart turns over at the sight of it – that “time”, in this context, is close to being a redundant term, as useless as a map or a bottle of champagne. US Airways flight 1539 was cleared for takeoff at 15.25.09; the bird strike took place at 15.27.11; the plane made its emergency landing at 15.30.43. In other words, between the engines dying and splashdown in the Hudson, there were just three minutes and 32 seconds. This morning – I cast him a feeble look, which he deflects with one of what you might call gracious pity – it took me longer than that to get of the house.

Can he describe those three minutes and 32 seconds? He nods, but I’m not sure that he really is able to, save for to make it clear that dying was the very last thing on his mind. What kicked in at this point was first his training and, second, his temperament: “I thought about solving all the problems we had and I was confident that we could do so, even though, at the outset, I wouldn’t have been able to tell you exactly what we were going to end up doing. Once I knew my only option was the river [LaGuardia and another airport, Teterboro, having been ruled out as too far away], I stuck with it. I didn’t waver. I knew it meant sacrificing the aeroplane. I knew people would be deciding whether what I did was right or wrong perhaps for decades. But that didn’t bother me. I didn’t let it interfere with what I had to do. I never once thought about my family or any extraneous thing at all. I was flying the aeroplane and I was flying it well.”

Sullenberger, born in 1951 and the son of a dentist, grew up in Denison, Texas. He knew he wanted to be a pilot as a small boy – witness the delight on his face in a photo taken on Christmas morning when, aged eight, his parents gave him a model aeroplane – and took his first solo flight, having had lessons from a crop-dusting pilot, at the age of just 16. In 1973, he graduated from the US Air Force Academy and thereafter enjoyed a military career – though he never served in any conflict – until, in 1980, he became a commercial airline pilot.

By 2009, then, he had more than four decades of experience in the cockpit, in fighter planes and in passenger jets. He still loved the job, but the cutbacks that had taken place in the industry since 11 September 2001, had also begun to get him down. Before he set off on the four-day trip that would end with the downing of flight 1549, he made himself two sandwiches, one turkey and one peanut butter and jelly. The airline no longer provided its pilots and flight attendants with meals, not even on longer flights. Almost the first question he would be asked by the accident investigators was about his blood-sugar levels that afternoon.

His schedule was to take him from Charlotte to Pittsburgh, where he and his crew would stop over for 10 hours, and then from Pittsburgh to Charlotte to LaGuardia, New York, and then back to Charlotte again. As the final leg began, he was in cheery mood. He and Skiles, a pilot with whom he had never flown before that trip, had made up some of the time lost earlier in the day, the snow had stopped falling and the flight he hoped to get from Charlotte back home to San Francisco was showing on time, with a seat available; it looked like he would make it there before his wife, Lorrie, and his two daughters, Kate and Kelly, went to bed.

Facebook Twitter Pinterest The eight-year-old Sullenberger receiving a model aeroplane on Christmas morning. He knew he wanted to be a pilot from a very young age. Photograph: Courtesy the author/HarperCollins

The plane had been in the air for about 95 seconds, and had not yet risen to 3,000 feet, when he saw them: a V-formation of Canada geese, birds that can weigh up to 18lbs and have 6ft wingspans. There was no time (that weasel word again) to react. The aircraft was travelling at 316ft per second and the birds were only about a football field away. The cockpit voice recorder captured what followed. “Birds!” said Sullenberger. “Whoah!” said Skiles. After this, there came thumps and thuds, followed by a shuddering sound. “Oh, shit!” said Skiles. “Oh, yeah,” said Sullenberger. Another noise could then be heard: a change in the plane’s engines. “Uh-oh,” said Skiles. Sullenberger had hit birds three or four times previously in his career and they had never even dented the plane, but this was different. He could feel the engines protesting, abnormal vibrations that signalled the destruction of the finely balanced machinery inside, and there was a terrible smell, too, of burning birds. Seconds later, he and Skiles felt a sudden, complete and bilaterally symmetrical loss of thrust. An eerie quietness fell. The only noise they could hear now sounded like a stick being held against moving bicycle spokes. In all his years as a pilot, he had never lost even one engine. Today, it seemed, he had lost two.

“My aircraft,” he said to Skiles. “Your aircraft,” Skiles replied. This was protocol. Sullenberger would now be at the controls and Skiles (who had to that point been flying the plane) would handle the emergency checklist, something that, believe it or not, he would now look up in the plane’s quick-reference handbook. Lucky they thought to make it “quick”. The plane was descending at a rate of more than 1,000ft per minute. If you can’t imagine this – I don’t want to imagine it – that’s the equivalent of a lift descending two storeys every second. Twenty-one seconds had passed since the bird strike. “Mayday! Mayday! Mayday!” said Sullenberger to Patrick Harten, the air traffic controller assigned to flight 1549.

At LaGuardia, the runway that could be reached by the shortest path was cleared. But it was no good. “We’re unable,” said Sullenberger. “We may end up in the Hudson.” In the circumstances, the river seemed relatively “welcoming”: it was long enough, wide enough and smooth enough. Plus, it was right there, available. Flight simulators don’t allow pilots to train for landing on water. But what other choice did he have? The only control he had over the plane’s vertical path now was pitch – the raising or lowering of its nose. His goal was to maintain a pitch that would give a proper glide speed, using gravity to provide the forward motion of the aircraft, slicing the wings through the air to create lift. Only about 90 seconds before he hit the water – when he would pull the nose full aft at last – did he address the passengers. “This is the captain,” he said. “Brace for impact.” Instructing passengers to brace is standard procedure. But he chose the word “impact” himself, hoping it would prepare everyone for what he thought might – might! – be a hard landing.

In his memoir, Sullenberger writes that even as he grasped that the plane, having hit the water, was intact, he worried about the difficulties that still lay ahead. It was sinking: everyone had to be evacuated and quickly. Outside, should anyone fall in, things would not look good for them; the temperatures were freezing, they would survive only for a few minutes. In truth, though, the next half-hour went like clockwork. Because the plane had landed between two ferry terminals, rescue vessels arrived quickly, the first within four minutes; people did not have to perch on the inflatable life rafts for long.

It was all so unreal. Sullenberger was soaked up to the waist, but his mobile phone, for instance, was still dry and working and he would soon use it to tell Lorrie what had happened, reaching her even before she saw the pictures on TV. A man on the wing could be seen holding on to his suit bag: “an unnecessary accessory at a time like that”, as he puts it.

Facebook Twitter Pinterest Hanks and Eckhart face investigators in the film. Photograph: Warner Bros

Following its investigation into these events, the NTSB made no fewer than 35 recommendations for safety improvements. Only six of them, however, have been adopted and Sullenberger, who, since his retirement about a year after the accident, now spends much of his time talking about such issues, is disappointed. “As a cost-competitive business, the industry is reluctant to take on extra safety measures unless they are mandated by the FAA,” he says. It was only by chance, for instance, that flight 1549 had lifejackets under every seat; most internal US flights still don’t carry them.

Meanwhile, certain risks increase. “Bird populations have grown and the number of flights has increased, so statistically speaking the risk of bird strike has gone up. People are working on high-frequency radars that can detect them earlier, but there is no magic bullet. Drones, too, are a growing problem. If medium-size birds can bring down an airliner, imagine what a drone might do. It’s only a matter of time.”

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Still, the greater part of him seems to regard what happened that day as a kind of blessing. “What you can get used to is amazing,” he says, showing me some of the medals for valour he has since received. “That famous flight has given me a bully pulpit that has allowed me to contribute greatly, to become a de facto spokesperson for my industry.”

It has taken him, too, to some wonderful places, among them President Obama’s inauguration. What, I wonder, does he make of Donald Trump, a man whose temperament is, it is quite obvious, diametrically opposed to his own? (Clint Eastwood was one of Trump’s starrier supporters.) For a few moments, he talks about leadership and team-building and I wonder if he is going to duck the issue (in 2009, the Republicans suggested he might run for Congress, and though he turned them down, he confesses he was “honoured” to have been asked). But, no. “I am very concerned about what has happened,” he says. “I hope that the people we’re talking about can rise to the occasion.”

Does he think that they will? I sense that he doesn’t. “We have survived many crises, just as the British have, and I’m sure we will find a way to survive even this,” he goes on, sounding like he has come straight out of The West Wing. “Years from now, we don’t want our grandchildren to ask us why we didn’t get involved, why we didn’t speak up when it mattered. I feel that obligation intensely and I think many others do, too.” He doesn’t salute, but he might as well have done. Sullenberger is, it seems, reporting for duty. Standing up, I’m almost tempted to click my heels.

Sully is released on 2 December. Sully: The Untold Story Behind the Miracle on the Hudson by Chesley “Sully” Sullenberger with Jeffrey Zaslow is out now (HarperCollins £8.99). To order a copy for £7.37 go to bookshop.theguardian.com or call 0330 333 6846