OPERATING MANUAL FLARM COLLISION WARNING UNIT
Version 4.06E Page 4 of 12 March 28, 2009
Installation and operation must be on the basis of non-interference with and no hazard to the existing suite of
other certified equipment necessary for safe flying operation, or installed to comply with official requirements.
Installation and operation must comply with official regulations and requirements. It is recommended that the
FLARM, GPS and radio antennae are all installed as far away as practicable - but at least 25 cm from -
susceptible aircraft systems such as GPS antennae and the magnetic compass.
The unit must be protected from solid particles or liquids, should not be exposed in use to temperatures
below –10°C or above +60 °C , or stored at temperatures –20°C or above +70 °C, because this may cause
irreparable damage. On the ground, the unit should be protected from exposure to long periods of direct
sunlight, because it is likely to be overheated. Also avoid static discharges to the radio antenna.
Details on correct installation are found in the Installation Manual. Ensure that you have configured the
correct aircraft type with the PC-software. Ensure that tug planes are configured as such!
4. Operating Modes
FLARM operates in two modes, Nearest and Collision. The change from one mode to the other is effected by
a two-second push on a button followed by a brief visual confirmation from the unit. After the change has
been signalled, the current mode selected is not displayed. When switched on, the unit is in Nearest mode.
The warnings given are identical in both modes, and generally relate to an immediate threat to which the
pilot should make an immediate and appropriate reaction. The assumption has been made that following a
warning it will take up to 12.5 seconds from the time that the other aircraft is seen, until a change in flight
path has removed the threat
2
.
When operating in the Nearest mode, the unit also reports the presence of other aircraft operating in the
vicinity, even though calculations indicate that they do not represent a threat. The information displayed is
limited to a configurable radius (default is three kilometres) and a vertical separation of 500 m. When no
aircraft was displayed so far but one is received now, this is signalled with a click-sound. Only one single
aircraft is indicated in green. The optical signal is static (no flashing); the threat intensity is not indicated and
there is no sound warning. As soon as FLARM detects the risk of a collision it automatically switches to
Collision mode, followed by automatic reversion to Nearest. The choice of mode is presented, such that
immediately after pressing the key, the display presents a diverging pattern .
When operating in the Warning mode a red LED lights up only if the calculation predicts a threat. Warnings
are always shown by flashing LEDs, the threat level being shown by the number of LEDs illuminated, by the
frequency of flashes, and the simultaneous sound signal (beep). Selection of this mode is indicated by a
upwards converging pattern immediately after pressing the selector key.
In both modes the pilot can suppress the display and the acoustic warning: after a double push FLARM
will suppress all visual and acoustic signals relating to traffic, obstacles or other threats. The act of selecting
suppression is followed by a descending tone. A further double-push reinstates the Collision mode at once
and is followed by a rising tone. While warnings are suppressed, FLARM nevertheless continues to transmit
signals for reception by other aircraft.
2
These times were published in 1983 FAA Advisory Circular 90-48-C and were based on military data. They relate to fast jet pilots with
no on-board warning systems for other traffic and hazards. The assumption was made that only one aircraft takes avoiding action. Of
the 12.5 seconds, five seconds were to recognise the threat of collision and four seconds were required to decide upon avoiding action.
No information is available as to whether these times are applicable to light aircraft, sailplanes or helicopters, when using a warning
system.
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