The reality of flying in extreme weather

Telegraph

3 days ago

Given the ever-changing patterns of tourism, airline routes tend to come and go pretty regularly. But Wizz Air's announcement last week that it will be scrapping all of its routes from Abu Dhabi (the capital of the United Arab Emirates and a bustling flight hub between Europe and Asia) may have raised more eyebrows than usual.
As well as the tough commercial and geopolitical climate in the Middle East, the low-cost carrier also cited the UAE's 'hot and harsh' climate as a reason for grounding the flights, adding that the high concentration of dust in the air was causing damage to its engines.
That the Gulf can be punishingly hot won't be news to anyone. But the idea that extreme temperatures can cause complications for planes seems like the sort of thing that frequent flyers might want to know more about – particularly if they plan on jetting to the region any time soon.
Too hot to handle
Most of the time, hotter temperatures are a matter of simple physics for pilots, says Nick Eades, a veteran captain of the legendary Boeing 747 and the author of several books. As the air heats up, it also gets lighter, which makes it tougher for a plane to get the lift it needs to take off properly.
'In days gone by, airlines had to adjust their schedules to avoid the hottest parts of the day, but modern airliners are able to operate in extreme conditions,' he says. At worst, the pilot may have to make some additional calculations, like reducing the amount of fuel on board to lower the plane's weight.
Once the plane has taken off, the heat is much less of a concern (although it may well add to turbulence at lower altitudes). Though planes that land in hot weather will usually experience a higher ground speed. 'To compensate, pilots will slow down much earlier and extend the flaps and landing gear earlier than normal,' he says.
Where hot weather has led to flight cancellations it's usually down to issues on the ground, rather than with per se. Last year, flights were briefly grounded in Delhi, for example, when safety authorities ruled that the airport tarmac had become too hot for a safe take off.
Closer to home, flights from London Luton Airport were cancelled for a day in summer 2022, after high temperatures caused parts of the runway to melt.
When the dust settles
In the case of Wizz Air's experiences in Abu Dhabi, though, the issue isn't necessarily the heat but the heavy concentration of sand and dust in the air – some of which gets sucked into the engine during take-off.
The extreme heat of the engine then means that much of that dust will melt, leaving behind a glass-like residue which can hamper the blades.
'This isn't like volcanic ash, where there is a risk of the plane falling out of the sky,' says Dr Claire Ryder, a meteorologist at the University of Reading who has led studies into the levels of dust around different airports. However, the gradual build-up and abrasion over time will result in performance issues for the aircraft engines, meaning lower fuel efficiency and higher maintenance costs.
For an ultra-low-cost carrier like Wizz Air, which relies on cutting back any possible costs to offer the cheapest tickets possible, that is a potential headache.
Given the massive aviation market in the Middle East, there is a sizeable incentive to develop engines that can better handle dust. At the University of Manchester, a team of researchers is working with Rolls Royce to conduct tests using synthetic dust, with the aim of understanding exactly what happens when it gets sucked into the engine.
'We know that the dust gets smaller the further it gets into the engine, but we are also looking at how it changes in its chemical structure,' says Dr Nicholas Bojdo, who is leading the project. The issue becomes more pertinent as engines get more powerful, as the increased capacity means that the temperatures get even hotter inside – thus exceeding the melting point for more minerals.
While temperature may be rising, the climate change models aren't particularly well equipped to estimate the impact on dust, says Dr Claire Ryder.
Though some studies show a correlation between rising temperatures and dust storms – the latter having led to flight cancellations (particularly in India) due to poor visibility.
Snowed under
Hot weather and dust are one issue, but what about the other end of the spectrum, when planes have to operate in harsh cold snaps? For all the disruption caused by snow storms and arctic blasts, the impact on the planes themselves is nowhere near as dramatic.
The typical cruising altitude of passenger jets means that they are already built to handle some seriously sub-zero temperatures. If anything, colder ground temperatures can make the engines more efficient. The wings can also be treated with a special anti-freeze to ensure they aren't affected by the outside temperatures.
If cold weather is going to cause problems it's likely to be on the ground. For example, snow blizzards can compromise air traffic control's visibility. In those circumstances, it's common for controllers to impose stricter safety limits, increasing the spacing between take-offs and arrivals. This usually means that some flights will inevitably be cancelled entirely.
Extreme cold weather may also cause runways to be closed off, as happened at four UK airports (Bristol, Newcastle, Birmingham and Manchester) back in January, when much of the country was under an amber warning for snow and ice. As a rule of thumb, aviation authorities warn against attempting take-off when the surface is more than 25 per cent ice or snow.
Perhaps Wizz Air won't be rushing to launch a Greenland or Alaska service any time soon, then. But it's good to know that, for those airlines prepared to splash the cash, the marvels of modern engineering can deal with extreme weather conditions – even if the airports themselves may not be so lucky.