Why the scorching heat in US Southwest is canceling flights

With temperatures approaching record highs this week in Phoenix, Arizona, American Airlines has had to cancel more than 40 flights in and out of Phoenix Sky Harbor simply because the planes can not take off.

American Airlines canceled more than four dozen flights in and out of Phoenix Monday due to operational concerns over extremely high temperatures in the desert city.

The National Weather Service forecasts a high of 120 degrees (49 degrees Celsius), which is has only hit three times in recorded history - the last time 22 years ago.

Customers affected were told to contact American Airlines for rebooking options or to request a refund. The carrier says that, for example, Airbus aircraft have a maximum operating temperature of 127 degrees and that for Boeing, it is 126 degrees.

Las Vegas could also see peaks on Tuesday and Wednesday, perhaps even gambling with its highest temperature ever observed, which was 117 degrees Fahrenheit in 2013. That hasn't happened since 2013, and it would be only the third time the city has reached that temperature.

Pilot Smith said electronics overheat, brake temperatures run high and internal machinery gets overly hot and then toss in ground temperatures racing past 110 degrees "and things begin to break down".

Wednesday in Phoenix started out breaking a daily heat record and signed off by breaking another.

In addition to grounding more than 40 flights of smaller planes, airlines have been taking other measures on larger jets to reduce their weight. According to the Arizona Department of Health Services, there were about 1,300 deaths from exposure to excessive natural heat from 2005 to 2015.

Hainan Airlines launched the first two nonstop flights from Las Vegas to Beijing in late 2016 but announced in May it was changing the departure times out of McCarran in the summer from late afternoon to early morning due to the heat.

"Yesterday in Phoenix we tied the record for past year, which was 47ºC, and now we are expecting to hit 49ºC today", Bianca Hernandez told AFP. The hotter the temperature, the harder it is for a plane to get enough air beneath its wings to lift it.

"People can go right from what they think is heat exhaustion to symptoms of a heat stroke which is actually a fatal illness", said Phoenix Fire Department Captain Reda Bigler.

"For Phoenix, that is limited to 118 degrees".

NSW also asked to the authorities and the people living in the region to take precaution while going out to survive the heat rage.

The main burn center in Phoenix warned people to be careful around auto interiors and pavement and with their pets. Others went to a bar where the temperature is set at 23 degrees and glasses, walls and seats are sculpted from ice.

When pilots try to take off in extreme heat the planes sometimes can not lift before the runway ends.