SkyDemon Traffic Display and Collision Avoidance
SkyDemon can display other aircraft on the main map and in a dedicated traffic display instrument, and it can also warn you when you are going
to get too close to another aircraft. It can only do this when connected to a traffic receiver device. There are various technologies for the
broadcast of aircraft position and trajectory (known as electronic conspicuity) and various products designed to receive it.
Electronic Conspicuity Technologies
There are three main technologies in use today for broadcasting information about your aircraft, which other aircraft may receive and use for
collision avoidance.
ADS-B
An international standard. Broadcast from your transponder or a standalone device. Emitted by most large aircraft and received
by the widest number of receivers. Transmissions occur in a protected band of the radio spectrum.
FLARM
A proprietary technology designed originally for gliders, but with many powered aircraft using it too. Devices can be portable or built in to
the aircraft. Transmissions occur on a consumer band of the radio spectrum.
P3i
A proprietary and open standard for broadcasting aircraft positions. Currently only broadcast and received by the PilotAware product.
Transmissions occur on a consumer band of the radio spectrum.
All three technologies perform the same basic function of transmitting your aircraft position and trajectory.
Broadcasting Your Position
The most important part of electronic conspicuity is broadcasting your position. It may be tempting to think about receiving first, but looking
at the bigger picture it makes a more significant difference to safety if your own aircraft is visible to everybody else.
There are many different products on the market which can receive various combinations of the technologies listed above. However, almost
every product can receive ADS-B transmissions. Therefore, it is our recommendation that whatever product(s) you use, you ensure your
aircraft is broadcasting its position using ADS-B. So, how can you broadcast ADS-B?
Using Your Transponder
Most transponders can be upgraded so that they broadcast your position as part of their return. To do this, they typically need to be
connected to a source of GPS information. Some of the receivers below can act as this source. Your avionics engineer can advise on this.
Using a Standalone Device
The CAP 1391 document
published by the UK CAA sets out how portable devices can emit ADS-B without having to be part of a transponder. So far only one
manufacturer, uAvionix, has marketed products fulfilling these criteria.
Receiving Other Aircraft
Once you are broadcasting your own position you will almost certainly wish to receive information on other aircraft, so you can use SkyDemon
to help you avoid an aircraft you may not have seen with your eyes.
There are many different products you can use to receive information on other aircraft. All the products broadcast with one
of the technologies above but also receive at least one of them.
- The receiver can detect aircraft transmitting FLARM when the customer has licensed FLARM decoding
functionality in SkyDemon.
- The receiver cannot detect FLARM transmissions itself, air-to-air. However if within range of a ground station (run by volunteers) then FLARM
traffic may be rebroadcast by the ground station and the device will receive it.
- The device cannot broadcast your position with ADS-B itself, but it can be connected to a compatible transponder by a qualified person to enable
that transponder to broadcast your position with ADS-B.
Mode S/C Reception
Some products support receiving basic aircraft data over traditional Mode S/C transponder returns. These do not include any position information, and therefore
SkyDemon cannot display them on your map or in the traffic instrument; we also cannot use the information for collision avoidance.