The history-making maiden 787 Dreamliner flight took off from Perth on March 24 to much applause. A whopping 17 hours and 20 minutes later, it touched down in London.

The new route — which is the world’s second-longest — was touted as a game-changer for the Australian tourism industry. But at 14,498 kilometres, there’s no doubt it’s gruelling.

And now, safety concerns have been raised over the extreme non-stop flights.

The airline has come under fire from Britain’s largest union, Unite, which alleges it has tried to “silence” crew concerns over fatigue on the route.

Unite brought the issue to light because the new route was operated exclusively by the airline’s subsidiary company, Qantas Cabin Crew UK, with all of the crew based in the UK.

It claimed that staff operating the direct flights had an average duty period of 19 hours, and an average rest period of 25 hours in a hotel before hopping on board a flight home.

This is insufficient and conductive to fatigue, according to the union.

“While the future of flying is likely to centre on ultra-long haul operations, Qantas has a responsibility to ensure that the safety and wellbeing of its passengers and cabin crew continues to be of paramount importance,” Unite regional officer Lindsey Olliver said.

“This simply cannot be compromised in the pursuit of profit … Qantas cabin crew must be provided with adequate rest down route between sectors to ensure they are fully able to complete their safety-critical functions without impairment while operating on-board an aircraft.”

However, Qantas denies this claim, stating that the crew get a minimum of 28 hours — and up to 52 hours — of rest.

A Qantas spokesperson told news.com.au of the allegations: “Making sure our crew have enough rest is important to us and something we’re very used to managing given our experience with ultra long-haul flying.

“These crew had previously been operating around seven hours of flying between London and Dubai, so we’re conscious there is a period of adjustment. Safety is always our main priority and we’re committed to working through any concerns constructively.”

Lindsey said it’s clear the airline needed to work on a solution.

“A key element to this must include a ‘just safety culture’ that allows crew to discuss safety concerns, wellbeing and fatigue, free from threats and the fear of reprisals,” Lindsey said.

“I urge Qantas in the UK to engage with Unite and listen to its workforce rather than resorting to bullying anti-union threats when dealing with legitimate safety concerns.”

The union is calling for Qantas to adopt a five- to six-day trip pattern instead of the current rostering practice. There are 10 cabin crew on board each 787 serving the route.

The International Civil Aviation Organisation defines fatigue as: “A physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase, and/or workload (mental and/or physical activity) that can impair a person’s alertness and ability to perform safety related operational duties.”

Airlines must take steps to reduce fatigue.

WORLD’S LONGEST FLIGHT ROUTES (BY DISTANCE)

1. Doha-Auckland, Qatar Airways, 14,529km

2. Perth-London, Qantas, 14,498km

3. Dubai-Auckland, Emirates, 14,200km

4. Los Angeles-Singapore, United Airlines, 14,114km

5. Sydney-Houston, United Airlines, 13,850km