According to the Federal Aviation Administration, almost 2,600,000 passengers fly in and out of US airports, every day. It would be safe to say that very few of those airline passengers give much thought to how extremely-cold weather can affect air-travel, aside from having to experience a canceled flight, from time to time.
Here, we’ll delve into how brutally-cold weather impacts not only scheduled flights, but the ability of aircraft to ever leave the runway.
Baby, It’s Cold Outside!
Surface contamination of a plane, including the accumulation of frost, snow or ice on wings and other surface areas will dramatically affect the lifting performance of the airfoil. It doesn’t take much frost, at all, to compromise the air’s smooth flow over the wings. Simply put, this can cause an increase in stall speed and a decrease in angle of attack, which refers to the angle at which the on-coming air meets the wing. In general, the greater the angle of attack, the more lift is generated by the wing. Quite stunningly, according to Air & Space magazine, it has been proven that it takes only a few millimeters of ice to increase the stall speed by a whopping 20%. To put that in clearer perspective, 1 mm equals 0.04 inches. Airline pilot and blogger, Patrick Smith says, “Even a quarter-inch-thick layer of ice on a plane can disrupt the flow of air over and around a wing’s carefully-sculpted contours, destroying lift.”
Planes CAN Fly in Extreme Cold
In January of 2014, bitterly-cold temperatures in the Midwest and Northeast caused airlines to cancel more than 6,000 flights over a period of 48 hours. Though planes can be deiced with a spraying of water and glycol alcohol, brake systems have been known to freeze while planes are in the parked position; though this type of problem is not common. Starting the engines can be a challenge when temperatures really dip; but in extreme cases, heaters can be applied to the engines, before starting. Bitter cold takes no prisoners, so to speak, since even the equipment used to pump jet-fuel can freeze, thereby, preventing planes from ever leaving the airport.
Assuming planes are allowed to fly in frigid weather, once they are in the air, it’s a whole different story. Air & Space magazine tells us, also, that temperatures at cruising altitude can be as low as -75 degrees Fahrenheit, or lower, since in-flight aircraft are designed to operate at these low temperature extremes. The outside temperature on a flight at 30,000 feet will, regularly, reach temperatures as low as -112 Fahrenheit without affecting the operational capabilities of a plane. It is the speed and the movement which keep the temperature in the engines and fuel tank much higher than the outside temperature. So, once the big birds are in the air, it’s ‘all systems go’ – the problems arise on the ground, before take-off, where brutally-cold temperatures can cause a lot of frustration for pilots, passengers and flight crews, alike.