The airspeed indicator is connected to both the pitot and static pressure sources. Pitot inlets are used for subsonic aircraft. Air France chose to equip its fleet with the Thales pitot tubes. Two of those incidents involved pitot probes. A pitot-static tube effectively integrates the static ports into the pitot probe. Another tool used to measure wind velocity includes a GPS combined with pitot tube. The pitot pressure is obtained from the pitot tube. The compass continues to operate despite failures in the electrical, vacuum or pitot static systems. A key part of the accident was a blocked pitot tube. The difference between the pitot pressure and the static pressure is called dynamic pressure. The pointer responds to the dynamic pressure from the pitot heads on the nose compartment. Tsien's experiments included plotting of pitot pressures using mercury-filled manometers. This is called the Pitot theorem. Students in Lacoste live in Maison Pitot, Fortunee, Renard, Murier, Olivier, and Basse.