It might be an unusual sight for Aussie or Kiwi travellers, but de-icing a commercial aircraft is crucial to prevent accidents in frigid northern hemisphere weather.
If you’ve ever travelled in the depths of a northern hemisphere winter, chances are you’ve looked out the window before takeoff and seen vehicles circling the plane, spraying de-icing fluid on the wings.
It’s a fascinating and highly-choreographed ritual, but have you ever wondered what it involves?
De-icing a plane is not just about removing a build up of ice or snow on the wings and tail of an aircraft, it’s also about preventing these icy build ups.
Ice is most serious when it forms on the wings of planes waiting to take off because it disrupts the flow of air across a wing’s upper and lower surfaces, affecting lift. And a plane most needs lift when it clears the end of the runway at takeoff.
Ice or snow can also disrupt the movement of the wing flaps and ailerons, making an aircraft difficult to control. Even a thin layer of ice around a wing’s leading edge can disrupt smooth airflow and cause a stall.
That’s why aviation rules require that an aircraft’s wings and tail be free of snow, ice and frost before takeoff.
De-icing heaters are also built into the leading edge of the wings of most commercial aircraft.
De-Icing At JFK
Whenever snow, ice or even frost accumulates on an aircraft’s wings, the pilots will call on trained de-icing crews (or ramp agents) to have it removed.
It’s something I witnessed last year on an early morning American Airlines flight departing New York’s JFK.
Once the aircraft pushed back from the gate at JFK, the pilots taxied to a ‘de-ice pad’ (an area on the tarmac that resembles a giant car wash).
Outside, where the temperature was barely above above 30F (-1 Celsius), the Airbus A321 was sprayed from top to tail and across both wings to remove ice and snow.
The clip below shows how ice was removed from the wing before takeoff using a telescopic spray boom.
If there’s a lot of snow or ice on the fuselage, they will spray it beginning at the top of the fuselage, just behind the cockpit, working their way toward the tail.
The de-icing truck circles the aircraft spraying about 190 litres (50 gallons) of de-icing fluid – a mixture of propylene glycol and water that is generally heated to 180 degrees and sprayed under pressure.
Another 95 litres (25 gallons) of anti-icing fluid is then used to prevent ice build-ups while the plane is waiting to taxi.
De-icing fluid can also be many different colours, including orange or pink, depending on the weather conditions, so it can easily be seen.
Often when de-icing is underway, the pilots will temporarily disable the aircraft’s ventilation system to prevent fluid fumes from entering the cabin. Although the fumes are considered non-toxic for inhalation, they do have a mild odour, often compared to maple syrup.
The whole de-icing process can take some time – anywhere from 10 to 20 minutes – but it’s always better to be safe than sorry.
Did You Know
American Airlines, like most carriers, uses state-of-the art de-icing trucks from Vestergaard, a Danish company that has specialised in de-icing equipment since the 1960s. Each truck costs around $US1.2 million.
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