One day in May this year, Luigi Rimonti left his home in Gateshead to catch a ferry from North Shields, the first stage in a 1,000-mile drive across Europe to Italy. A dapper, energetic 81-year-old, Rimonti had grown up in a suburb of Rome before coming to the north-east of England as a young man. Often, over the years, he had driven back to Rome, insisting to his two adult sons, Gino and Valter, that he preferred to make this long journey by car. They worried about their father on these drives, and this spring, for the first time, they persuaded Rimonti to equip his car with a satellite-navigation device.

Off the ferry in Amsterdam, Rimonti began to have difficulties with the satnav. He stopped in a petrol station: could someone there help him re-input his destination? A stranger obliged. Tap-tap-tap, enter. Rimonti thanked the stranger and drove on – south, he presumed, towards Rome.

After a day’s driving, Rimonti was looking forward to stopping somewhere for an overnight rest. The satnav hadn’t taken him on a route he recognised, but he seemed to be making good progress. He was surprised, then, to be told by the smooth, computerised voice of the satnav that he’d shortly be arriving at his destination. He had clocked hundreds of miles, though not yet the 1,000 he knew it would take to reach Rome. Rimonti’s son, Gino, picks up the story: “Dad was like, ‘This isn’t Italy.’ So he got out to check where he was. He must not have pulled the handbrake on properly.”

Luigi Rimonti was surprised to be told by the smooth, computerised voice of the satnav that he’d shortly be arriving at his destination. Photograph: Christian Knieps/BILD

Rimonti had stopped his car on a slight slope. When he clambered out, the better to read the nearest road sign, his car began to roll backwards. Struck by the open door of the car, Rimonti was knocked over and dragged along. When the car struck the very road sign he’d been trying to read, it jolted, and Rimonti was able to tumble clear. He lay in shock on the road. His suitcases and belongings were now trapped in the boot of the car, which had been crunched shut by the collision. The car had also immobilised itself and would later be towed. Rimonti lay still, shaken and badly injured, too hurt to stand. He later told his sons: “Pensavo di essere morto.” I thought I was dead.

The road sign he had been trying to read was on the ground beside him. “Rom,” it said, identifying this location as a tiny hamlet in the hills of Mecklenburg-Western Pomerania in Germany, due east from Amsterdam and a good 600 miles from the Italian border. Rimonti would be in Pomerania for the better part of a week, recuperating. Rome would have to wait.

Luigi Rimonti’s car in Rom, Germany, after he followed his satnav, which he thought was taking him to Rome, Italy. Photograph: CEN

We live in curious times, part-digital, part-manual. It’s a hybrid era that presumably won’t last for long, and in which we’ve come to rely on code and algorithms to handle many of our affairs, though usually with a human hand setting everything in train. Miracle tech! Unimaginable automation! And so much of it conditional on an accurate animal prod at the outset, a finger landed correctly on a keyboard, a thumb touching the right quarter-inch of screen, a mouse button clicked just so.

Things go wrong. Back in March 2015, a single misplaced digit (15 degrees 19.8 minutes east, entered into a cockpit computer, instead of 151 degrees 9.8 minutes east) led to a passenger jet bound from Sydney to Kuala Lumpur landing in Melbourne. In January 2018, an extraordinary clerical error led to a million Hawaiians being texted the news that their destruction by ballistic missile was imminent. “Seek immediate shelter,” the message read, “this is not a drill.” Not a drill, no: an inaccurate click, later tracked back to one computer, one drop-down menu, one government employee who was a few pixels off in their aim.

In our almost-automated age, we tend to be asked to do our bit at the beginning of any enterprise, before a million digital processes occur quickly, incomprehensibly, out of sight. When things do go wrong, it can seem as if we’ve pushed the first domino in a long run and then turned away, trusting the dominoes will fall neatly. Err on that first nudge, and the consequences can be amplified far out of proportion to the initial mistake.

Two years ago, in a hospital in Tennessee, a nurse clicked to order the wrong drug from an electronic medication cabinet (like a vending machine for pills). She wanted anti-anxiety medication for a patient. She ended up administering a poison meant for killing prisoners on death row, and is now on trial for reckless homicide.

Don’t panic after all! Hawaiians are told to ignore the warning of a missile threat in January 2018. Photograph: Cory Lum/AP

Around the time of the 2018 Hawaiian missile debacle, it became a weird hobby of mine to look out for the starkest and strangest examples of these butterfly-effect typos. I made a note whenever a notable instance crept into the daily news cycle. A tweet by Donald Trump, this summer, that referred to Prince Charles as “the Prince of Whales”, launching a frenzied few hours of meme-making. The 46m Australian banknotes that went into circulation recently, missing a letter “i” in the word “responsibilty” in the small print. Benign stuff, mostly. You hear these stories, chuckle or wince, and move on. I began to wonder about the inadvertent keystrokes that had larger, longer, crueller effects. Of all the one-off typos and misclicks, had there been a world’s worst?

From a study of court reports, I knew it was not uncommon for convicted drug dealers, out on remand, to send poorly aimed text messages to their own parole officers offering them drugs. There have been hasty key presses that trigger even heavier state machinery. In March, members of the European parliament voted via touchscreen on whether to amend a crucial aspect of copyright law. It was a close-run thing and, after the vote, more than a dozen MEPs – enough to have made a difference – admitted they’d pressed the wrong option by accident. Parliamentary business had moved on, though. The law passed without amendment.

In 2009, there was an extraordinary instance of one-click bedlam that could not be undone. An employee at Companies House was scrolling through a list of UK firms, trying to find a Manchester business called Taylor & Son that had been issued with a winding-up order and would soon cease to exist. Then came the blunder. The employee wrongly selected the Cardiff-based Taylor & Sons (note the plural) and began the process of liquidating that firm instead. Taylor & Sons was a thriving engineering company that had been trading since the 1870s. It had been making about £35m a year, according to Philip Davison-Sebry, who ran the business in 2009.

A single-digit typo tied one man's computer, via its IP address, to someone else’s who was accessing child abuse images

Bad-credit notices were issued. Clients got spooked and cancelled business. Suppliers began queueing up at the firm’s six factories to be paid. Soon, Taylor & Sons really did need to fold. Administrators came in, and centuries of reliable trading came to a halt overnight. Davison-Sebry was 52 at the time, and suddenly out of work. “It’s hard to find another job in your 50s, believe me,” he says, now. “Especially when everyone thinks you’re the guy who collapsed a 200-year-old business.”

Earlier this year, while researching this story, I took the train to Sheffield to meet a man called Nigel Lang. If there has been a world’s worst typo, it may be the one that devastated Lang’s life in the summer of 2011.

A friendly, slightly wary man in his early 50s, Lang shows me around the home he shares with his partner, Clare, and their young son. Lang was 44 in 2011. He had a job he liked, as a drugs counsellor for Sheffield council. The family was just back from a summer holiday when, one Saturday morning, police officers rang the doorbell. Lang re-enacts the scene for me, standing up from the kitchen table where he had been having breakfast with his family, opening the door, and then reeling back when he was told why the police had visited.

Lang was to be charged on suspicion of downloading child abuse images. He was told that an IP address, provided to South Yorkshire Police by Hertfordshire Constabulary, had led investigators to a laptop he owned. Could he come to the nearest police station for questioning? “My body just contorted,” Lang tells me. “My legs went to jelly.”

After he’d dressed and left with the police, his house was searched for computers and storage devices. At the time, according to Lang, he was not especially computer literate. There was one family laptop that he used to stream reggae music. Taken for questioning, he struggled to answer basic inquiries about the internet (“Web browser? You mean like Google?”). When officers asked if he wanted a solicitor, Lang panicked. “I don’t need a fucking solicitor! I haven’t done anything!”

Much later, years later, he would learn that a single-digit typo had tied his computer, via its IP address, to someone else’s crime. But that first Saturday, waiting in a cell, Lang knew none of this. His brain was reeling. When he was told a forensic search of his computer could take up to six months, and that until it was complete he would remain in limbo, thoughts of suicide flashed through his mind, he says.

Meanwhile, at home, Clare was going through her own difficulties. Social services had come, and Clare was told that although Lang would be released while his computer was searched, he could not come home to live with the family. As Clare recalls: “I asked them: ‘What would you do if I allowed him to come?’ They said: ‘We’ll take your son off you.’” Hours earlier they’d been eating toast together. Now Clare was being asked to choose between two members of her family. “An impossible situation, because if you believe your partner, you’re thought to be putting your child at risk. I felt completely helpless.”

In the end, the family waited three weeks – “Like a lifetime,” Lang says – for the computer search to be completed. Lang was living with his parents when he was told the police had not found anything. The charge was dropped and he was free to move back home. Even then, Lang says, he found himself compulsively telling everyone he met what had happened, fearful they would hear about it in some other way. According to Clare, “Nigel was in bits.”

Later, Lang realised he was having a breakdown. “You think everyone is looking at you with scepticism. Suspicion,” he says. “You can see people mulling things over in their minds, weighing it up. ‘How’s this happened? What were you looking at to make this happen?’”

Some disastrous typos are at least reparable. In the 1960s, Nasa operatives watched as one of their new Mariner space rockets veered off course over Florida. Deep in the guidance software of the rocket, a lone dash had been left out of the code. On that occasion, engineers were able to explode the straying rocket in the sky before it could hurt anybody on the ground.

After the accidental missile alert in Hawaii, there were about 20 minutes of civil panic before government workers got word out that the alert had been sent in error. When I contact the head of the government agency responsible, Vern Miyagi, he tells me that the accident might even have been beneficial for the islands, in that they will be better prepared for any real emergency.

The police owned up to the mistake that had led to the wrongful charge. 'There was a typing error'

In Wales, after struggling for years to get back on his feet, Philip Davison-Sebry took Companies House to court for the error that crushed Taylor & Sons. He won damages of more than £8m, and has since founded another company.

The cruelty in Lang’s case was that there seemed no thorough way of reversing what had gone wrong. Despite the charges being dropped, the fact that he’d once been arrested on suspicion of downloading child abuse images remained on Lang’s record: an unacceptable taint. Clare says: “Emotionally, it was like Nigel wasn’t there. I remember being at the kitchen table and he was blank, like he’d left the room without leaving the room.” Lang tells me: “Your mind’s constantly on clearing your name. You can’t think of anything else.”

He fought a legal battle for years. In 2014, three years after the arrest, Lang received a letter from Hertfordshire Constabulary, in which the police unequivocally owned up to the mistake that had led to the wrongful charge. “There was a typing error,” a detective inspector confirmed. “An extra digit added on the form… Cannot convey how sorry I am…”

Lang thought: sorry? He’d stopped working. He’d alienated friends. The loyalty between him and his partner had been tested in the extreme. Now he felt a weird compulsion to know something else: exactly which wrong keystroke had started his troubles?

There was further inquiry. Lang was told that Hertfordshire Constabulary had meant to track a person using an IP address ending in the number six. A number one had been added, and the rest was history, years of Lang’s history. At his home, picking through documents related to the case, he sighs. “It’s just one of those things, isn’t it? One you can’t ever explain.”

Lang has been awarded a five-figure sum in compensation. But it is plain to see, while spending time with him, that the incident has scarred him. I feel doubly sorry for Lang, because in researching this story I also come across a woman from Missouri who is something like his polar opposite – a lottery winner on the spectrum of fat-fingered flukes. If lives can be “smashed up”, in Lang’s words, by a single wrong keystroke, it stands to reason that lives can be made better by the same thing.

She pressed in a chunky number six, not a zero. There had been a marriage as a result

Happier events were set in train for Kasey Bergh, a 53-year-old divorcee from St Louis, thanks to some imprecise thumb-work back in 2006. She had bought one of the old Nokia phones with plastic buttons, and was hastily filling its address book with the numbers of friends and colleagues. Bergh must have wrongly input a number because, six years later, when she tried to text that colleague, her message went astray. It pinged on to the phone of a stranger who lived about 900 miles away, in Colorado.

Henry Glendening, a man in his 20s, was driving to work at a hardware store when Bergh’s text came through. He tapped out a pert, positive reply: “Sorry, you’ve got the wrong number. But if I wasn’t headed to work I’d be down to hang.” Bergh was charmed. They kept texting. After a while – despite the age difference, and the distance between their hometowns – the pair began dating. They married in 2015.

A misdirected text led Kasey Bergh to her future husband – and kidney donor – Henry Glendening. Photograph: St Louis Post-Dispatch/TNS via Getty Images

Telling me her story, Bergh realised that she hadn’t properly got to grips with how that first cross-communication occurred. Her curiosity piqued, she went off to investigate, digging out the old Nokia and contacting the former colleague whose number she got wrong. It turns out she pressed in a chunky number six, not a zero – a difference of a few millimetres. There had been a marriage as a result of those millimetres; followed by other, potentially life-saving consequences.

For decades Bergh suffered from a serious kidney illness. She had already received a transplant when she and Glendening met and, after their marriage, that donor kidney began to fail. Glendening offered one of his. Donor-compatibility tests were conducted and, this spring, the couple underwent the operation. When I last spoke to them, in May, they were in recovery, bleary and happy. Bergh sends a smiley emoticon, perhaps not trusting her shaky fingers to accurately type much. The surgery has gone well.

Luigi Rimonti, who’d been intent on Rome and landed in Rom, also required a stay in hospital. After an hour on the stony ground in Rom, an ambulance wound its way to the remote hilltop town to collect him. As the 81-year-old’s suitcases were trapped in the boot of his car, he was admitted to hospital without fresh clothes. The car was a write-off. Rimonti’s pride had taken a hit, too, and when he finally called his sons to tell them what had happened, he said brusquely: “There’s been an accident. I’m alive.” Then he hung up. For days, this was all his worried relatives knew.

Genuinely catastrophic typos, like the one that caused Rimonti so much trouble, tend to draw a crowd. People like me are queasily fascinated, perhaps because these incidents remind us that basic bad luck is something that hasn’t yet been smoothed away or tamed by science. While Rimonti was lying in a Pomeranian hospital, his story became international news. A German journalist got wind of what had happened, and soon there were reports about the case on local television. The story spread around Europe. Before long, Rimonti’s sons were being sent confusing clips of foreign-language news items about their father. One channel even put together an animated map of his journey. The English tabloids ran stories. All this before Rimonti’s sons got him home.

When he finally walked in the door in June, Rimonti was bruised, car-less, uncertain on his feet, bemused by the world’s reaction to his escapade. What drama for one missing letter “E”! His son, Gino, blamed the satnav. Hadn’t Rimonti always driven to Italy by his own devices, reading road signs, feeling his way, “like a penguin going home. If we’d just let him drive there, I think he’d have made it.” They should never have let technology interfere with something so primal, Gino jokes.

Meanwhile, I have been thinking the opposite: that tech really has to get a lot better, so that voice commands, or even thought commands, can override our inherent bent for sloppiness.

Luigi Rimonti takes the broader view. There is only one lesson from his misadventure: “La vita è una merda.” I’ll translate that one with a typo, for decency: in life, siht happens.

• This article was amended on 5 August 2019 to remove text that contravened the Guardian’s style guide.

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