Davtron’s Model 655 is a computer-based product that computes density altitude automatically. No longer does the pilot need to retrieve outside air temperature and pressure altitude, then enter this into a flight computer. The Model 655 measures outside air temperature, and accepts pressure altitude information from the blind encoder or encoding altimeter, then converts this information to a direct read-out of density altitude. The density altitude is computed using U.S. standard atmosphere tabulation. Take-off roll, maximum rate of climb, and fuel consumption are all determined easily from density altitude and the aircraft’s flight manual.