Friday, February 8, 2008

East to West, West to East

Hello again,

I have had several questions about why it takes so long to fly to the west coast and it is so short fling from the west coast, eastbound. The simple answer is this: headwind.

That answer usually gets a funny look and an "I know that" response. The mechanics of how the headwind and tailwind actually effect the plane are this. Airplanes all fly based on and in reference to 'Airspeed'. This is how we determine how fast we are going. Air Traffic Control (ATC) will ask: "what's your airspeed?" Airspeed is defined as the relative speed through the air that an airplane is flying. Simple right? Well, yes and no. There's several different kinds of airspeed such as Calibrated, True, Indicated, etc. For this segment, we'll deal in True, which is that speed the plane is moving relative to still air.

Back to the wind. When the wind is on the nose (headwind) of the plane, at say 100, and the plane is going 400 the head wind is subtracted from the true airspeed and you get a ground speed of 300. So in 5 hours, you will fly 1500 miles. Conversely, when you have the same plane turned around the other direction, the wind is now acting as a tailwind and you add the 100 to the 400 and you now have a ground speed of 500. That means the same 1500 miles will be a 3 hour flight.

Hopefully, this answers that question. Again, if you have anything specific, feel free to ask!!