Another tool used to measure wind velocity includes a GPS combined with pitot tube. The pitot pressure is obtained from the pitot tube. The Pitot tube supplies pressure to the airspeed indicator. A key part of the accident was a blocked pitot tube. The basic pitot tube consists of a tube pointing directly into the fluid flow. In these kinds of measurements, the most practical instrument to use is the pitot tube. A blocked pitot tube is a pitot-static problem that will only affect airspeed indicators.