Technical Analysis: Why Airlines Had To Cancel Flights Due To High Temperatures In Phoenix

By Stephen

Phoenix, the capital of the southwestern state of Arizona in the U.S.A is in the news after around 40 flights were cancelled on Tuesday, June 20th. Most of the cancelled flights were those of American Airlines, and the airline had announced that the flights were cancelled during the hottest part of the day, as the temperature was too hot for them to take off.

The incident happened at the Sky Harbor airport, and the cancellations were all for regional flights - routes on which American Airlines operated their Bombardier CRJ aircraft.

Why Were Flights Cancelled Because Of High Temperatures

Temperatures at the airport were touching 120-degrees Fahrenheit (49-degrees Celsius), but the Bombardier CRJ was designed to operate at temperatures of up to 118-degrees Fahrenheit (48-degrees Celsius). So, can higher temperatures affect the operability of aircraft? Well, in the case of this particular aircraft, turns out it does affect it.

Aircraft fly with four forces acting on it at all times. One is 'thrust', which is generated by the engines and accelerates the aircraft opposing 'drag', which is the force of air, which tries to slow the aircraft. The other is 'lift' which, is generated by the wings and lifts the aircraft in air opposing 'gravity' which tries to pull the aircraft down.

Why Were Flights Cancelled Because Of High Temperatures

Lift can be generated only when air passes over and under the wings at a high rate, meaning the aircraft has to be at significant speed, which is the exact reason for long runways so that the aircraft can gain momentum. So the whole concept of flying is two forces of physics acting against the other two forces.

Another fact that physics has taught us is that the density of air reduces as temperature increases. The problem faced by the Bombardier CRJ aircraft at Phoenix was that at normal take-off speeds too, the thinner air was not able to hit the wings with enough momentum to generate enough lift for the aircraft to take off.

Why Were Flights Cancelled Because Of High Temperatures

The CRJ is a series of small-capacity aircraft manufactured by Canadian aviation company Bombardier Aerospace. The CRJ 100/200 can seat only 50 passengers and the largest of the series is the CRJ 1000 which can seat 100 passengers. This brings us to the other problem that this aircraft faced - wing area.

The Bombardier CRJ 100/200 has a wing area of just 48.35 square metres. That is a pretty small wing area, and this combined with the low air density did not allow for safe take-off conditions. A more powerful engine might have offset these disadvantages, but the aircraft is powered by twin engines from GE with a take-off thrust of 8,729 pound-feet each. Not sure how good that is?

Why Were Flights Cancelled Because Of High Temperatures

Just to draw a comparison, the Airbus A-320, a larger aircraft used on regional routes by many other airlines has a wing area of 122 square metres, and is powered by twin CFM engines with 22,000-27,000 pound-feet of thrust each. Aircraft like the A-320 and larger aircraft with more powerful engines could operate out of the Sky Harbor airport. Turns out size does matter after all doesn't it?

Why Were Flights Cancelled Because Of High Temperatures

DriveSpark Thinks!
Small aircraft like the Bombardier CRJ and Embraer 135 do have their advantages, such as being able to operate out of a small airport and land/take off at really short runways. On a few hot days though, it is best to bring out the big guns, or should I say big engines?

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Read more on: #aircraft #offbeat #analysis
Article Published On: Wednesday, June 21, 2017, 15:50 [IST]
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