Page 776 - PPL-engelsk 2025
P. 776
Aircraft general knowledge
An airplane is hovering over the North Pole with its nose pointing in the direction
of Akkasut’s igloo. The pilot is sitting and looking at his heading gyro.
o
To him, it appears as if the gyro is wandering 15 to the left every hour.
In reality, it is the rotation of the earth that he is seeing!
o
o
24 hours of 15 gives 360 in a day.
Because of this, we must adjust the heading gyro regularly during flight.
8.12.8.1 Sources of error
Another source of gyro
“wandering” is bearing wear
and instrument inaccuracies.
When constructing gyro
instruments, one must know
how a gyro is reacting on
forces applied to the gyro.
The reaction of an applied force to the gyro shows 90⁰ later in the direction of
rotation of the spinning gyro, and in same direction as applied. This attribute is
called “precession.”
The precision of the gyro is used in the turn indicator.
The law of physics says that if you affect a rotating gyro, the effect will be 90
degrees behind in the direction of rotation.
Watch a short film of the gyro here.
Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 776
