OPERATING MANUAL FLARM COLLISION WARNING UNIT
Version 4.06E
Page 9 of 12
March 28, 2009
11.
Aircraft Anti-Collision Warnings
An illuminated red LED indicates the approximate bearing to an aircraft currently posing the biggest threat of
collision. The bearing is
relative to the track.
This indication is inaccurate if there is a strong wind, if the
aircraft is in a sideways yaw / slip, or if ground speed is very low (e.g. when a helicopter is in the hover). The
display is refreshed every second.
The unit emits an audio warning (beep) tone at the same time as the flashing red optical warning. The time
between the warning and possible collision is brief, just a few seconds. Warnings of fixed obstacles are given
slightly earlier.
Horizontal indication
The twelve bicolour LED show a compass rose, i.e. the birds view on the traffic situation. ‘Top’ is track-up
according the own aircraft. Each LED covers an equal-sized horizontal sector of 30°.
If the threat is moderate (less than 18 seconds to possible collision), a single LED lights up; in the case of a
medium threat (less than 13 seconds) then two diodes light up; if the threat is imminent (less than 8
seconds) three LEDs. The threat is at the centre of the illuminated block. The flash and beep frequency
increases with the threat.
Moderate threat from ca. 3 o'clock
(less than 18 seconds to calculated collision)
Slow flash at 2Hz
Moderate threat from 1 to 2 o'clock
(less than 18 seconds)
Slow flash at 2Hz
Medium threat from 1 o'clock
(less than 13 seconds)
Medium flash at 4Hz
Immediate threat from 1 to 2 o'clock
(less than 8 seconds)
Rapid flash at 6Hz
Medium threat from the rear, 5 to 7 o'clock
Medium flash at 4Hz
Moderate threat from the rear right, 4 to 5 o'clock
Slow flash at 2Hz
Vertical indication
The vertical bearing is indicated by a vertical
line of four red LEDs and show the bearing
relative to a horizontal plane. This is independent of the aircraft’s climb angle. The
uppermost or lowest LEDs illuminate when the bearing exceeds 14°. The LED flash
frequency is identical and synchronous with that of the horizontal display.
Traffic indication (only in Nearest-mode)
In Nearest-mode the closest aircraft is shown in green as long as no warning is necessary. Traffic indications
don’t flash, there is no sound and the distance is not shown.
Traffic around 2 o’clock
No flashing
Traffic around 7 o’clock
No flashing
