It’s been a long and turbulent time since anyone used British Airways’ old slogan “the world’s favourite airline” with a straight face. After a decade during which the UK flag carrier was tarnished by cost-cutting, IT fiascos, mass redundancies and strikes, BA was then pushed to the brink by Covid.

Hopes of a smooth recovery disappeared like lost luggage on a carousel, as cancellations and delays plagued an airline seen as pricier than short-haul competitors and dowdier than the Gulf carriers. With burgeoning complaints about customer service, pledges by bosses to turn things round were met with some scepticism.

And yet, something strange has happened. The share price of IAG, the Spanish-registered group whose fortunes rest predominantly with BA’s, has doubled in the past 10 months to levels uncharted since before the pandemic – and not just on the back of growing profits revealed in November. City analysts have concluded that BA really – no, really – is getting better after all.

Last Christmas, the airline’s chief executive, Sean Doyle, started talking of the turnaround – confident enough to relocate festive drinks from central London to a Heathrow arrivals lounge to showcase BA’s new offering to grumbling journalists. He promised more was coming: comfier seats, better-quality service, improved reliability. In spring, the airline showcased its plans for a £7bn investment, in an effort to stem the perception that BA was getting left behind by global rivals.

And now, investors appear to be buying it. Andrew Lobbenberg, Barclays’ head transport analyst, says: “It really is on an upward curve, albeit from what was quite a low starting point.

“Coming out of the pandemic with a poor product, multiple IT failures, huge staff shortages, they struggled desperately. The operational performance, the flight cancellations were a dreadful mess. The wine, the food had been penny-pinched, the seats were old fashioned.”

And, “running a bad airline is expensive”, Lobbenberg adds. The back end, including long-awaited investment in IT of £750m, is one of the less apparent but potentially critical developments in restoring operations. A new customer app, replacing the clunky booking website and enabling swifter responses when disruption strikes, is also due in early 2025.

According to BA, that has paid dividends. Last month, it was hit by a 90-minute IT outage that left planes stuck on the asphalt, but instead of a situation escalating badly as it has done in the past, the airline ended up with only delays and no cancellations.BA has also hired an extra 1,000 staff on the ground at Heathrow, 500 more cabin crew and another 640 staff for customer call centres to increase its resilience when things go wrong.

Nonetheless, the bumpy ride has continued: efforts to address failing punctuality have been hampered by factors from airspace to spare parts. Its fleet of Boeing 787 Dreamliners has had its wings clipped by problems getting their Rolls-Royce Trent engines repaired. And, according to a BA spokesperson, far more of its flights (42%) have been affected by air traffic control (ATC) regulation than those operated by the airline’s European competitors.

The spokesperson adds: “While the vast majority of our flight cancellations are forced upon us due to weather, airspace restrictions or supply chain issues and are unavoidable, we’ve been able to reduce them by almost 40% since last year, while also outperforming other UK and European competitors on punctuality at their own hub airports.”

However, Guardian analysis of flight data from the Civil Aviation Authority shows that while BA has been able to, at times over the last 12 months, boast better punctuality rates than both easyJet and Ryanair at their main UK hubs, those airlines have been more likely to outstrip the performance of others at the airport.

Ryanair, which dominates Stansted with an 80% market share of flights, has experienced a marked dip in punctuality through the peak season – and fewer than half of easyJet’s flights departed within 15 minutes of schedule from Gatwick over summer. However, easyJet, which like BA has its own terminal and around half the traffic at its London hub, has outperformed others at Gatwick. BA has only managed to match the rest of Heathrow for punctuality in two months.

Nonetheless, BA’s cancellation rate has been significantly lower than during a difficult 2023, with fewer than one in 50 flights at Heathrow axed over the course of the year – at least until September, a month when a combination of bad weather and ATC constraints resulted in more than 4% of departures being cancelled.

The aviation analyst John Strickland, once of BA himself, says much of the recent criticism of the airline has been justified, even with challenges outside its direct control. “It has to assess internal processes, how delays and cancellations are handled, communicated and fundamentally reduced to restore trust,” he says.

Until that is won, the branding and halo effect of BA’s spending on its customer creature comforts – refurbished lounges and better seats, with a swanky first-class suite to follow – still threatens to be unravelled by a mistimed sausage. Regular business-class flyers were infuriated when the airline decided to replace lunch with a cooked brunch on late-morning departures.

One vocal critic, Rob Burgess, the editor of the business travel site Head for Points, says: “There’s nothing I’d like more than for BA to be a genuinely world-class airline. But when they serve a bit of bacon for lunch to slash food costs, it’s a ludicrous own goal.

“They benefit from being the flag carrier – that also means people do expect more from them.”

The brunch trial is being quietly phased out, despite BA claiming it has had good feedback. But it also spoke to the importance of the trend, particularly on the lucrative transatlantic routes, for leisure passengers to upgrade to the expensive seats, replacing the dwindling market in corporate travel.

“The problem is they actually want something for their money. The private individual paying £2,500 to fly to the US actually expects a clean lounge and decent wine and genuine value, in a way that business travellers really don’t,” says Burgess.

If BA gets it right, analysts believe, the airline is well-positioned to take advantage of those customers – certainly dollar-rich Americans.

“It’s in the right markets, geographically, and with its premium positioning,” says Lobbenberg. “Brunch-gate was obviously a mistake. But in the broader picture, the customer satisfaction is climbing. The employee satisfaction is climbing.

“Complaining about BA is a bit of a national sport. But it is, in clear objective terms, getting better.”