Question

This value is encoded by a kind of Gray code using twelve bits, or four octal digits, called the Gillham code. Devices that measure this value include a small “Kollsman window”, named after their inventor Paul Kollsman. While Mode A transponders only broadcast identification, Mode C transponders additionally transmit this value. Regions where this value is between (15[1])FL 180 and FL 600 are considered class A, meaning only IFR operations are allowed, (15[1])as opposed to classes B (15[1])through E that allow both IFR and VFR. The rate of change in this value is measured by a (*) variometer. A TCAS (“TEE-kass”) system monitors differences in this value and gives commands to increase or decrease this value as a safety measure. (10[1])Both velocity and this value are approximately kept constant during a holding pattern. For 10 points, devices that measure what value utilize the fact that atmospheric pressure decreases (10[1])as this value increases? ■END■

ANSWER: aircraft altitude [accept height; accept elevation; accept flight level or FL before “FL”; accept vertical position or vertical distance but prompt on just “distance”] (TCAS stands for Traffic Collision Avoidance System, which prevents mid-air collisions.)
<AW>
= Average correct buzz position
Conv. %Power %Average Buzz
100%60%93.00

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