Flight 3407: Weather in Buffalo & Aircraft Icing

Written by: Brian Neudorff

The investigation continues into what caused Continental Flight 3407 to crash into a house in Clarence Center, NY around 10:20 p.m. Thursday night. One of the possible causes that has been theorized is icing occurring on the planes wing.

At 10 p.m. the National Weather Service reported the following surface weather conditions. An air temperature of 33 F, winds were out of the west at 17 mph gusting to 25 mph. Light snow and a mist was reported with a visibility of 3 miles.

These weather conditions are not uncommon for Buffalo in the winter and although very strong and gusty winds impacted the region for most of the day Thursday, they had subsided 10 to 20 mph with just light snow & mist around the time of the crash. There was reported chatter and discussion with other planes about the conditions and ice showing up on some of the planes.

Anything at this point is just speculation but I came across a very informative article about what aircraft icing is from Aerospaceweb.org. They point out that, "icing is most common on smaller prop driven airplanes, such as commuters and general aviation aircraft." Which appears to be what flight 3407 was, a Bombardier Q400, a twin-engine turboprop.

In the simplest of terms, icing can occur when air temperatures approach freezing this cools the metal surface of the plane to the same temperature. Then water droplets in the air or rain can freeze when it comes in contact with the surface of the plane. At times, liquid water can already be below freezing, we call this "Supercooled" water and this will also freeze immediately on contact with the plane's surface.

When this ice accumulates on the wing of a plane it changes the way air flows over and around the wing. This change has a negative effect on the aircraft performance.

Ice that collects on a lifting surface causes a reduction in the maximum lift and maximum angle of attack and an increase in drag. It is the reduction of the angle of attack that is usually the most significant problem. In the case of the wing, this reduction usually becomes a factor during an approach to land, when the angle of attack is increased, and the speed reduced. Due to the ice, what was previously a safe angle of attack is now a dangerous one, causing the wing to stall (lose lift) and nose down. During an approach, an airplane is usually close to the ground, which means a sudden loss of lift can have disastrous results.

All of this is speculation but temperatures were near freezing at the surface and below freezing the higher up you went. There was light snow and a wintry drizzle as the atmosphere was close to saturation, this is a very possible theory on what happen but there is still a lot to do before any of these questions are answered.