六级阅读常见考点解析（3）：特殊标记_大学英语阅读

六级阅读常见考点解析（3）：特殊标记

In 1958, Australian scientist David Warren developed a flight-memory recorder that would track basic information like altitude and direction. That was the first mode for a black box, which became a requirement on all U.S. commercial flights by 1960. Early models often failed to withstand crashes, however, so in 1965 the device was completely redesigned and moved to the rear of the plane the area least subject to impact from its original position in the landing wells (起落架舱). The same year, the Federal Aviation Authority required that the boxes, which were never actually black, be painted orange or yellow to aid visibility.

Modern airplanes have two black boxes: a voice recorder, which tracks pilots conversations, and a flight-data recorder, which monitors fuel levels, engine noises and other operating functions that help investigators reconstruct the aircrafts final moments. Placed in an insulated (隔绝的) case and surrounded by a quarter-inch-thick panels of stainless steel, the boxes can withstand massive force and temperatures up to2,000℉. When submerged, theyre also able to emit signals from depths of20,000 ft. Experts believe the boxes from Air France Flight 447, which crashed near Brazil on June 1,2009, are in water nearly that deep, but statistics say theyre still likely to turn up. In the approximately 20 deep-sea crashes over the past 30 years, only one planes black boxes were never recovered.