For years, ‘see and avoid’ has been the primary means of aircraft maintaining separation from each other and the ground.
The flaw in the concept is that often the other aircraft, or indeed a mountain, cannot be seen and the situational awareness so vital to the safe conduct of the flight can be degraded to a dangerous level.
Hazard warning systems fall into one of two broad categories: traffic and terrain. Some manufacturers do package them together as one system.
Generally, traffic and terrain systems are listed as options on EFIS, with the inputs going mostly to the MFD.
Systems fitted with synthetic vision, such as the Chelton and Garmin SVT, can also cast the indications behind the PFD to create a comprehensive flight awareness display.
Traffic systems come in various types, each with its own acronym.
TIS, TAS, TCAS and ADS-B are the most common you will see bandied about nowadays, and the difference between them can be very slight.
Australia’s low-level ADS-B project is in the reject box at the moment, although the system is active in the flight levels.
Terrain warning systems such as TAWS and EGPWS work on a colour-code warning system and indicate high terrain relative to the altitude of your aircraft.
Red colours and yellow colours are the ones to worry about, as they indicate a real possibility that you are about to smear your aeroplane across the landscape.
Avidyne
Avidyne produces a complete range of hazard warning systems to be integrated with their EX500 and EX5000 MFDs.
Their TAS 600 series (traffic advisory system) is based on the same technology used in transport-category TCAS (traffic collision avoidance system), but it only warns of proximity, it does not provide resolutions.
This system detects and interrogates the transponders of other aircraft within range, displaying the traffic on the MFD and providing an audible warning.
The standard 600 is recommended for standard piston aircraft and has an active range of 7nm and shows all traffic within 3,500ft vertical separation.
It is only good up to 18,500ft.
For higher performance aeroplanes, Avidyne suggests the TAS 610, which will cover 12nm and has a service ceiling of 25,000ft.
The TAS 620 goes another step further and looks out 21nm and shows anything within 9,900ft vertically. As it is good for up to 55,000ft, it is best suited to corporate jets and the like.
The TAS 600 series is compatible with 15 different EFIS manufacturers, including major competitors Garmin and Honeywell Bendix King.
Terrain warning systems are built into the Avidyne MFD range and are based on the internal database.
Bendix King
The main traffic system from this stable is the KTA 970 TCAS I.
This works by interrogating the transponders of other aircraft in flight, then processing that information to clearly display the positions on an MFD, such as the KMS 850.
The system can track up to 60 aircraft and display information on up to 30 of them.
Pilots can select from eight ranges from 2nm to 40nm and show three levels of ‘intruders’: non-threat, proximity and Traffic Advisory (TA).
Non-threat is at a level more than 1200 feet above or below and at a distance of five nautical miles.
The symbol is the conventional TCAS hollow white diamond.
Proximity means that the intruder is within the 1200ft envelope and inside five miles, showing up as a solid white diamond.
The bad one, TA, means that the KTA 970 has decided the contact is a threat because the closest point of approach is within 30 seconds.
If a TA occurs, the indicator turns to a solid yellow circle, an audible warning is given and, if not active, the KMD 850 screen will switch to traffic automatically.
Traffic indicators at all levels include an arrow that shows if the contact is climbing or descending, which can help you make an informed decision on evasive action.
BK also produces two EGPWS terrain systems that link to the KMD 850: the KGP 560 and KGP 860.
The 560 is a basic system suitable for the majority of GA aircraft and the 860 is most suited to turbo-props and light jets.
SEE BELOW FOR MORE HAZARD WARNING SYSTEMS PHOTOS...