INTRODUCTION TO AIRCRAFT FLIGHT INSTRUMENTS
Aircraft flight instruments are divided into three categories according to their specific function.
The attitude instrument indicates the aircraft's attitude in relation to the Earth's surface, the
position instruments convey the aircraft's location in space, and the performance instruments
indicate how the aircraft is performing as a result of attitude changes.
For information concerning a specific aircraft's instrument, consult the applicable NATOPS
201. ATTITUDE INSTRUMENT
The primary flight instrument in all naval aircraft is the attitude indicator. It provides the pilot
with a substitute for the Earth's horizon as a reference in instrument flight. The instrument
shows a horizontal bar representing the horizon upon which a miniature aircraft is superimposed.
There are graduated scales on the instrument's face to indicate Angle of Bank (AOB) and pitch.
The combined indications provide a constant visual presentation of the aircraft's flight attitude as
it relates to longitudinal, vertical, and horizontal information. Some aircraft installations may
have additional information displayed on the instrument, such as heading, glideslope
information, turn and bank, yaw, and course deviation. Aircrews should refer to the appropriate
NATOPS flight manual for detailed operation of a particular system.
202. PERFORMANCE INSTRUMENTS
these errors. Only non-gyro-stabilized (standby) compasses will be discussed in this section.
Gyro-stabilized compasses will be discussed later.
The standby magnetic compass is simple in construction. It contains two steel magnetized
needles mounted on a float, around which is mounted the compass card. The needles are
parallel, with their north-seeking ends pointed in the same direction. The needles react to the
Earth's magnetic field and cause the compass card to indicate magnetic heading relative to
magnetic north. The compass card has letters for cardinal headings and numbers every 30º in
between. The last zero of the degree indication is omitted. Between these numbers, the card is
graduated for each 5º.
The standby compass is used for training or cross-check purposes or when any kind of failure
renders the gyro-stabilized compass useless. One of the principal reasons for the reduced
importance of the standby compass is the large and variable amount of heading deviation
present. Variable electrical loads, armament, and the position of the nose landing gear create
deviation errors for which compass correction cards cannot provide sufficient tolerance. The
gyro-stabilized compasses largely eliminate these errors.
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