According to the ATOMATOFLAMES acronym, what instrument indicates the altitude of the aircraft?

The correct answer is the altimeter, which is the instrument designated to indicate the altitude of the aircraft in flight. The altimeter works by measuring the atmospheric pressure outside the aircraft. As the aircraft climbs or descends, the changing air pressure is translated into altitude readings. This is crucial for pilots to maintain safe altitude levels, avoid obstacles, and comply with air traffic control instructions.

The ATOMATOFLAMES acronym is a mnemonic device used in aviation to remember the required instruments and equipment for visual flight rules (VFR) flight. "ALT" within that acronym specifically refers to the altimeter, highlighting its importance in monitoring altitude during flight operations.

Other instruments listed do not provide altitude information. The manifold pressure gauge measures the pressure in the engine's intake manifold and is primarily used in piston engines to assess engine performance. The temperature gauge assesses the engine or oil temperature, necessary for engine management but not related to altitude. The fuel gauge indicates the amount of fuel remaining, important for ensuring sufficient fuel is on board but unrelated to altitude measurement. Thus, the altimeter is the sole instrument among the options that fulfills the requirement for indicating the aircraft's altitude.