Pitot-Static Instruments
The Pitot-static instrument system consists of the altimeter, air speed indicator (ASI), and vertical speed indicator (VSI). The displayed values are calculated using a mix of static and ram pressure from the static ports and pitot tube ( ERAUSpecialVFR, 2016) . On December 1st, 1974, a Boeing 727-200 experienced catastrophic system failure resulting from an iced over pitot tube. Following a takeoff from JFK Intl. Airport, the aircraft climbed to 13,500 feet; after levelling off, it accelerated from 264 to 305 knots and began climbing at 2500 fpm. Eventually, the aircraft surpassed 340 knots and 6500 fpm. An overspeed warning horn sounded at 23,000 feet at 405 knots, after which the plane pitched down and began descending at 15,000 fpm. It descended more than 23,000 feet in 83 seconds before striking the ground. Common system failures include a blocked static port or pitot tube. In flight, most blockage resul...