Page 787 - PPL-engelsk 2025

Aircraft general knowledge

8.12.10.5 IMU (Inertia Measuring Unit)

If you place such a system in all 3 axes,

"filter" the information and then

computer-process it, you get very

accurate replacements for the
equipment that our planes from the 70s

were born with.

In addition to altitude, the equipment also measures the earth's magnetism. This

may require that "remote sensors" are placed far from things that can affect the
relatively weak magnetic inputs that come from the earth's magnetism.

Magnetometers are the electronic sensors that gives us heading reference.

By using GNSS (Global Navigation Satellite System), you also get heading

references. You are now free of having to periodically set a heading gyro

according to the compass corrected for deviation. So, it increases accuracy and

safety during flight.

Initial ALIGNMENT (adjustment)

When you start the system, an initial

alignment takes place, where the integrated

parts calculate attitudes and headings.

It may be necessary to hold onto a horizontal

place until the system is up and running.

In the picture here, you are asked to keep the

wings horizontal while the system starts up.

Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 787