The story of how failing to de-ice an aircraft properly led to the fatal crashes of two Two Fokker F28s.

On March 10, 1989, Air Ontario Flight 1363 took off from Dryden Regional Airport (YHD) and crashed 49 seconds later. Three years later, a similar event occurred when USAir Flight 405 crashed while taking off from LaGuardia Airport (LGA) in Queens, New York City. What both accidents had in common was that they were both operated by the Fokker F28 Fellowship and had failed to be de-iced before attempting to take off.

Following the commercial success of the Fokker F27 Friendship turboprop, Dutch aircraft manufacturer Fokker wanted a larger version of the plane powered by jet engines. Called the Fokker F28 Fellowship, they marketed the aircraft as a 65 seat regional commuter jet. Introduced in 1969, Fokker further developed the plane until the last variant, the F28-4000, arrived in the early 1970s. Powered by quieter Rolls-Royce Spey 555-15H engines, the aircraft featured a modified wing, a new cockpit, and a capacity to carry 85 passengers.

Air Ontario Flight 1363 was a regularly scheduled flight between Thunder Bay International Airport (YQT) in Ontario to Winnipeg James Armstrong Richardson International Airport (YWG) in Manitoba. Both the captain, 52-year-old John Morwood, and first officer 35-year-old Keith Mills were highly experienced pilots yet relatively new to flying the Fokker F28 having only 150 hours between them.

During the stopover in Dryden, it was snowing, and snow started to settle on the wings. Usually, the pilots would ask for the aircraft to be de-iced, but on this occasion did not as they needed to keep one engine running. The Fokker 28 manual stipulates that the plane cannot be de-iced if an engine is running because of the danger of toxic fumes entering the cabin.

Dryden Airport did not have an operating auxiliary power unit (APU), which meant that if both engines were shut off, they would be unable to restart them without power. The decision was made to skip the de-icing and keep one engine running. As the plane took off, it could not gain height and struck trees at the end of the runway, killing 21 of the 65 passengers and three of the four crew members, including both pilots.

USAir Flight 405 was a regularly scheduled flight between LaGuardia Airport (LGA) in New York and Cleveland Hopkins International Airport (CLE) in Ohio. On March 22, 1992, the aircraft, a Fokker F28 Series 4000, had just arrived in LaGuardia from Jacksonville, Florida, and was delayed on the taxiway getting to the gate because of congestion. Now running an hour late, the captain advised a ground mechanic that his airplane was "good to go."

While the pilots disembarked to use the toilets, the plane was de-iced using a heated 50/50 water/glycol mixture. After the de-icing, one of the de-icing trucks suffered a mechanical failure, blocking the aircraft from departing the gate. After the truck was repaired, the plane's captain, 44-year-old Navy veteran Wallace J. Majure II, asked for the plane to be de-iced a second time. When the pilots returned to the aircraft, neither the captain nor first officer did a walkaround of the plane to make sure all was well as it was not required to do so in the USAir procedures.

After the crew completed their pre-flight checklist while taxiing out to the runway, the captain announced that the flaps would remain in a retracted position and that they should not be worried. To remind himself of the position of the flaps, he placed an empty coffee cup on the flap's handle. The captain informed the first officer that they would be following standard USAir contaminated runway procedures for takeoff. These included the flaps being set at 18 degrees and a reduced V1 speed of 110 knots. Despite having been recently plowed at the time of takeoff, runway 13 was coated with a thin layer of wet snow.

Despite the poor weather, LaGuardia remained open, and flight 405 was permitted to take off from runway 13. As the wheels cleared the runway, the aircraft failed to gain altitude and continued flying just yards above the ground. The plane suddenly veered to the right, where it collided with several obstructions before ending up in Flushing Bay. Of the 51 passengers and crew, 27 were killed, including the captain.

When investigating what had happened after the crash, it was determined that pilot error and poor deicing procedures at LaGuardia were at fault. Following lengthy delays, ice had been allowed to form the plane's wings. In its report, the National Transportation Safety Board (NTSB) said the pilots were unaware of the ice on the plane's wings and that the aircraft was trying to take off at too low a speed. They also determined that the deicing procedures at LaGuardia were sub-par and that the mixture used at LaGuardia and other airports across the United States for deicing was only effective for 15 minutes. Following USAir flight 405, studies were carried out into the effect ice had on aircraft leading to new prevention techniques.

When tiny cloud droplets of water impact a plane, ice typically builds upon the plane's leading edge or front surface. The ice then alters the airflow over the wings resulting in a reduced lift force, potentially causing an aerodynamic stall and temporary loss of control. Ice can form on aircraft in two ways:

On the ground, rain or snow falls on the plane and freezes on the upper surfaces, much like it can do overnight on your car. Ground icing forms on the upper surfaces of the plane's wing and tail and is managed by ground crew spraying a mixture of water and chemicals to melt the ice.

While in the air, ice can build up on the leading edges of the wings, the nose, and the tail. During the winter, when water is condensed out of the atmosphere to form clouds, the water vapor that makes up the clouds can be because of its purity maintained at a lower temperature than freezing point. When an aircraft flies through the cloud, the water in them now has a surface to freeze on. Ice then builds upon the frontal surfaces, which affects the airflow over the wings. To combat this, planes can allow the ice to build up and then get it to crack and fall off by using pneumatic rubber boots or prevent it from forming by using hot air from within the engine's compressor.

Another example of a crash caused by a deicing failure is Colgan Air Flight 3407.

Journalist - Mark is an experienced travel journalist having published work in the industry for more than seven years. His enthusiasm for aviation news and wealth of experience lends itself to some excellent insight, with his work cited in Forbes amongst other publications. Based in Alicante, Spain.