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9.10.4 Radar
Radar comes from RAdio Detection And Ranging.
There are 2 types of systems:
- Primary radar / ground radar
- Secondary radar / SSR radar
9.10.4.1 Ground radar / primary radar
Ground radar is used to check whether there are aircraft in an airspace.
A ground radar works by emitting radar waves at short intervals. An aircraft will
normally reflect some of these waves.
The radar is equipped with receiving equipment that displays the reflected rays
on a screen. By measuring the time from the emission of an impulse until the
impulse is received again, the radar can calculate the distance to the aircraft.
The range of primary radars is from 25 to 500 km.
There are different versions of primary radar, depending on the requirements
the radar must meet.
- ASR Radar: Airport Surveillance Radar, used by tower control
- PAR Radar: Precision Approach Radar, used by departure and approach
controllers
- LLR Radar Long Range Radar
- SRE: Surveillance Radar Element, used within a limited area, e.g. a terminal
area, where radar vectoring can be given to the aircraft
9.10.4.2 SSR Radar and transponder
Primary radar is not suitable for radar control. That is the SSR Radar.
If the reflected rays could be coded with answers, one would have come a long
way.
Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 900
