What Am I: Traffic technology

What do triangles and diamonds mean to a student pilot? If you’re not already familiar with them, in the near future these symbols have the potential to give pilots a never-before-experienced degree of situational awareness in the cockpit.

These shapes, when presented on a panel-mounted display or a tablet, represent other aircraft with which you’re sharing the sky. They’re brought to you by Automatic Dependent Surveillance-Broadcast (ADS-B), aspects of which will be required in some aircraft beginning early next year. Traffic and weather information are optional, but have the potential to improve flight safety through increased situational awareness.

ADS-B uses GPS satellites instead of ground-based radar to determine aircraft location and is a key technology behind the FAA’s Next Generation Air Transportation System. The FAA will require ADS-B Out for flights after January 1, 2020, in airspace where a transponder is required today.

If the aircraft you fly already has ADS-B In, an appropriate display will depict other moving aircraft as triangularly shaped arrowheads that point in the direction that the target is moving. Traffic targets with no direction or speed information, or that are stationary, will be shown as diamonds. The difference between your altitude and the target’s altitude, in increments of 100 feet, is shown with a “+” indicating it’s above your current altitude and a “–” denoting that it’s below you.

On most displays, when a traffic target is within 5 nautical miles horizontally of your position, and within 1,200 feet vertically, its depiction will turn yellow. In some installations, when the target gets closer you may receive an aural alert through your headphones: “Traffic two o’clock, two miles.”

ForeFlight, which provides a popular subscription app displaying ADS-B data, cautions that because of cumulative inaccuracies in pressure altitude systems, any target shown to be within 500 feet vertically of your aircraft should be treated as though it is at your altitude. As the pilot in command it’s your responsibility to see and avoid other traffic, and to follow instructions from air traffic control. ADS-B data is considered advisory only and should never be relied upon as your sole means of traffic avoidance.

Depending on the source of the traffic information and the display that you’re using, the depiction also may include the aircraft’s tail number or flight number, vertical speed, and/or a leading line or vector that shows anticipated movement for that target.

If your aircraft offers a means to display ADS-B traffic information, you also should be able to see Flight Information Service-Broadcast (FIS-B) weather data. This subscription-free information includes Nexrad radar images, METARs, TAFs, airmets, sigmets, convective sigmets, pireps, and winds and temperatures aloft. New weather products added during fall 2018 included lightning strikes, turbulence, icing, cloud tops, graphical airmets, and Center Weather Advisories.

Don’t know if the aircraft you’re flying is ADS-B-equipped, or whether it has ADS-B In capability? Ask your instructor and become familiar with FAR 91.225, which defines the airspace where ADS-B Out will be required—after January 1, 2020, you won’t want to be flying there in an unequipped aircraft.