On December 21, 2015, a Jetstar Boeing 787 flying from Melbourne to Singapore experienced a failure of all three Pitot tubes due to ice crystal accumulation. The incident occurred at an altitude of 12 kilometers, approximately 450 kilometers north of Darwin, leading to the loss of airspeed data and the automatic disconnection of the autopilot.
The Pitot tube, an instrument dating back to Henri Pitot's 1732 invention, measures airspeed by converting dynamic pressure into a readable value. Modern aviation standards, such as the 2018 ETSO-C16b, require these sensors to be equipped with drainage systems and baffles to mitigate the impact of moisture, ice, and debris on pressure readings.
Discrepancies between indicated and true airspeed are inherent to the design of aircraft instrumentation. Instruments are calibrated to display speed as if the aircraft were flying at sea level in standard atmospheric conditions. Consequently, at cruising altitudes, the indicated speed significantly differs from the actual ground speed.
The indicated airspeed remains critical for flight safety because it directly correlates with the aerodynamic forces acting on the wings. Aircraft wings respond to dynamic pressure rather than true airspeed, meaning that stall speeds and approach parameters are calculated based on the same pressure-derived data provided to the cockpit displays.
