Sunday, February 15, 2009

More on Flight 3407: Icing and Steve Chealander's Comments


This guy from the NTSB, Steve Chealander has made some questionable statements.

1. That the de-icing equipment had be turned on 11 minutes after take-off.

2. The auto-pilot was on during decent.

3. Significant icing does not represent severe icing. (He is playing a game of semantics)

4. Based on weather data , there was no indication of severe icing. (The skew-t data for Buffalo shows icing conditions from moderate to severe)

5. The pilots had winter training that tells you to engage de-icing equipment before entering icing conditions.

Here is what is said about anti-icing and de-icing equipment.

Chealander stated de-icing equipment had been turned on 11 minutes after take-off. De-icing equipment (the boot system) is turned on after encountering icing, anti-icing equipment is turned on before entering icing conditions.

The problem with the boot system is that if left on for sometime, it can malfuntion in that icing gets lodged in the system and cannot expand.

As for data on icing, the following graph will show areas of icing. As stated on the graph, the highest percentage of pilots encounter icing will be in area A. Here are graphs on icing conditions in Alaska and the CONUS.

The Skew-T data on the day of the crash is below and shows that the potential for icing is high. And from my own forecasting experience, it could be moderate to severe.

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