The Dutch airline KLM has offered “sincere apologies” to a Paralympic athlete who was denied access to an onboard wheelchair during a long-haul flight so she could go to the toilet.

The cabin crew on the flight later called the police after the request from Hannah Babalola, 37, who is paraplegic and competes in track events, for the wheelchair, known as an aisle chair as it is narrow enough to be used inside a plane. They first handed her a written notice, headed: “Unacceptable conduct and final warning on behalf of the captain of this plane.”

The incident happened on 26 May, when Babalola, who competes for Nigeria and lives in Chicago, was returning home from a wheelchair-racing event in South Africa.

She had booked the KLM return flight from Chicago to Cape Town, via Amsterdam, as a wheelchair-using passenger. The outbound flight went smoothly, but as she began her return journey she was taken to the plane by wheelchair and asked by cabin crew, once she had boarded, if she would require an aisle chair during the flight. When she said she would – the flight to Amsterdam was almost 11 hours – the problems started.

In a conversation with cabin crew and the captain that she asked permission to record, which was shown to the Guardian, a crew member can be heard saying they could not accept a passenger in need of an onboard chair as it was too dangerous to use during a flight in case of turbulence and that Babalola’s two options were to go to the toilet without using the wheelchair or to “offload” from the plane.

“I needed to get home to Chicago to my family and to get to work and I couldn’t ‘offload’ from the flight,” Babalola said.

Security was called by the cabin crew but declined to take any action against Babalola. When the flight landed in Amsterdam, the crew asked the police at the airport to be on standby, but they too declined to take action.

Babalola transferred to a different connecting flight in Amsterdam to complete the journey to Chicago.

She said: “I felt compelled to avoid eating or drinking for the duration of the flight because I feared needing to use the restroom and being unable to access it. I spent much of the flight trying to control my emotions and I found myself crying because of the way I had been treated.

“This experience was humiliating, distressing, and degrading. The situation caused me significant physical discomfort and emotional distress. I believe that the manner in which I was treated raises serious concerns regarding discrimination and equal treatment. All passengers, regardless of disability or personal circumstances, deserve to be treated with dignity and respect.”

Babalola made a formal complaint to KLM about her experience.

A member of KLM’s customer service staff replied, stating: “It is very concerning to read about this experience, particularly the distress caused during boarding and throughout the flight. Your account describes a situation that must have felt deeply upsetting and unsettling, especially when travelling with an accessibility need and simply expecting appropriate assistance and respectful treatment.”

They added: “A full review of the circumstances should now be carried out by the appropriate teams. This will typically include examining the reports submitted by the crew and any other relevant information available in relation to the flight. My sincere apologies are extended for the distress and upset this experience has caused.”

The British Paralympian Anne Wafula Strike hit the headlines in 2017 when she was forced to wet herself on a train. The incident triggered a national debate about equal access to transport for people with disabilities.

She said: “Nine years ago I was forced to wet myself on a train because there was no functioning accessible toilet. Almost a decade later, the experience of Hannah Babalola shows we still have a long way to go. It is upsetting that disabled people are having to fight the same battles over and over again just to access the rights that able-bodied passengers have.”

A KLM spokesperson told the Guardian: “We regret that an incident occurred involving one of our passengers on the flight from Cape Town to Amsterdam on 26 May. Out of respect for the privacy of both the passenger and our crew, we find it inappropriate to discuss the details of the situation.”

The cost of travel to and around the UK is keeping millions of tourists away and slowing economic growth, the boss of British Airways said, as he urged a rethink of aviation taxes.

The airline’s chief executive, Sean Doyle, said the UK had some of the highest aviation taxes in the world and was falling behind countries such as Japan, France and Germany in boosting its inbound tourism.

The UK would not hit ambitious targets for domestic tourism without making travel easier and more affordable, Doyle added.

Air passenger duty across most flights was raised by 15% in April, up to £8 a passenger on domestic flights, £15 for European departures, and up to £253 in premium economy seats on long-haul flights.

“What’s the biggest challenge in the country at the minute? It’s growth. And what should policy be doing? It should be unblocking growth. If you want to promote tourism and aviation … the last thing you do to encourage that expansion is put the cost of it up,” Doyle said.

The government has set a target of welcoming 50 million international visitors to the UK by 2030, up from about 40 million tourists at present.

However, Doyle warned: “Unless we address the affordability issue we’re not going to get there. If you look at France and Spain, they’ve absolutely shot past us. A big part of it is cost, if you look at the surveys. If we want to hit 50 million and want the economic benefit of that, we’re going to have to change the affordability proposition to tourists.”

He said aviation taxes on flights around and out of the country were a factor, as well as rail ticketing: “The other thing is the lack of options to travel around the UK, because of things like rail networks which are fragmented, the lack of [rail] passes – the lack of a kind of curation of tourists is a big issue.”

“We end up with tourism concentrated in places like London and Edinburgh, but the rest of the economy doesn’t get the benefit of it.

“I think air passenger duty is a part of that – for a family of five coming into the country and travelling, it’s a huge penalty compared to what you pay in Europe.” EXAMPLE OF TAX RATES HERE?

Speaking to reporters at an international airlines summit in Rio, the Iata annual meeting, Doyle also warned that the government’s backing for Heathrow’s third runway in pursuit of economic growth could backfire if the airport developed its own scheme at the cost of airlines paying higher charges and reducing their own investments.

BA and other airlines have urged the government to pursue a cheaper alternative scheme for a third runway than the current £33bn preferred option proposed by the airport.

Doyle said: “There’s an ambition on infrastructure expansion in Heathrow, but if the cost is too high, the other side of that growth, which is airlines coming in with planes and investing their capital into the sector, that may not come.”

Flights to the Iata summit were provided by Iata and Latam airline

A proposed travel card for northern England modelled on London’s Oyster system could save commuters up to £276 a year, data shows.

Users would tap in and out across different transport networks and fares would be automatically capped at the cheapest available rate.

Researchers estimate the scheme could generate up to £2.7bn for the economy over five years by making it easier for people to travel between towns and cities for work, training and leisure.

The proposal would link together transport systems across northern England including Greater Manchester’s Bee Network, West Yorkshire’s planned Weaver Network and South Yorkshire’s People’s Network, allowing passengers to move between regions without buying separate tickets.

The scheme is backed by the Good Growth Foundation thinktank and the Labour MP Luke Charters. Supporters argue that while city regions across the north of England have invested heavily in improving local transport, travelling between those networks can involve navigating different ticketing systems, fare structures and operators.

The proposed card would create a single payment system across multiple modes of transport. Passengers would be able to use a bank card, phone or dedicated travel card, with software calculating the cheapest fare automatically and applying any relevant daily or weekly caps. Concessions for groups such as students, older people and disabled passengers would be applied across the network.

Praful Nargund, the director of the Good Growth Foundation, said a unified ticketing system would help people feel less “cut off” from job opportunities in the region. “One tap, one fare cap, and suddenly those opportunities become realistic options, where that is a better job or a great night out,” he said.

Sources close to the Greater Manchester mayor, Andy Burnham, told the iPaper that he was interested in the concept of an “Oyster card for the north”. Burnham has previously argued that better transport links are essential to boosting economic growth and connecting communities across northern England.

Charters, the MP for York Outer, said the growth of integrated transport systems across northern city regions meant the foundations for a wider contactless network were already being put in place. “Anyone in the north will tell you getting from A to B is still harder than it should be,” he said.

The proposal comes as mayors across the north continue to pursue greater control over local transport networks, after the rollout of Greater Manchester’s Bee Network.

No formal plans for introducing the travel card scheme have been announced but campaigners argue that ongoing transport changes across the north create an opportunity to develop a single ticketing system spanning multiple networks.