The Garmin GDL 39 combines a dual-link ADS-B (Automatic Dependant Surveillance Broadcast) receiver and GPS into a single unit. Now you can get ADS-B datalink traffic, weather and GPS positioning from a single portable device. The cost conscious will be happy to hear that weather service is subscription-free.
The GDL-39 is an ADS-B In device, which outputs to a Garmin portable or any mobile device running Garmin Pilot. The GDL-39 is compatible with:
- aera 796-795
- aera 500 series GPS
- GPSMAP 696/695
- G3X experimental flight display
- output via Bluetooth to Garmin Pilot app-compatible devices (including the iPad!)
Integration with other Garmin devices is pending. Specifically, Garmin anticipates integration with the G1000 avionics suite in January 2014.
The GTX 330 and 33ES transponder units must have their firmware upgraded by Garmin to receive traffic. Contact an authorized Garmin dealer for assistance.
Comprehensive Weather Information
The Garmin GLD-39 uses ADS-B input technology to receive free Flight Information Service Broadcasts (FIS-B) from the FAA-maintained 978 MHz Universal Access Transceiver (UAT) uplink. The following information is at your fingertips:
- animated NEXRAD radar (5-12 minute sweep depending on radar)
- winds and temperatures aloft
- And more!
You get comprehensive weather information at a glance. Keep in mind that FIS-B is delivered line-of-sight by ADS-B antennae. Here is a map of current coverage:
These antennae work by line-of-sight — meaning, in some cases, you have to take off to position yourself within the LOS of an antenna. Furthermore, proximity to an antenna gives you a clearer, higher-resolution weather map. Aircraft equipped with ADS-B Out devices pass on information to other aircraft within range automatically so it is possible to get weather information in this manner.
ADS-B In and Out
The Garmin GDL-39 supports ADS-B In only information. This provides weather and traffic information but is limited by the ADS-B antenna coverage pictured above.
For best results, combine the GDL-39 with an ADS-B Out device. This provides more accurate traffic information as well as better weather information. In the event that your cockpit contains multiple ADS-B reception devices, the GDL-39 assesses information integrity and displays the most complete data to the pilot.
The GLD-39 receives ADS-B In signals on both available frequencies (978 UAT and 1090 ES).
Garmin GDL-39 vs. Zaon
The GDL-39 seems to be a direct head-to-head competitor with Zaon’s collision warning devices. In this head-to-head comparison, the Garmin wins in the display category. The GDL-39 offers more features (especially if you have ADS-B In/Out capability): weather, traffic and GPS.
However, the Zaon devices are much simpler, and deliver critical positioning information. Furthermore, Zaon devices don’t depend on ADS-B output of other aircraft. Instead, Zaon uses XM satellite coverage. On the downsite, word around the pilot shop is that the Zaon tracks a limited number of targets and defaults to closest targets. We’ve heard complaints of false alarms, too. (And there’s no iPad support, if you’re into that kind of thing).
Some pilots prefer an uncluttered, single-output device to juggling multiple inputs from the same device. For those of you who have trouble multi-tasking on your iPad, a Zaon MRX Collision Avoidance System ($500) may be a better choice.
On the other hand, the GDL-39 definitely helps to provide a clearer picture of the skies all around.
Spot traffic threats
The GDL-39 alerts the pilot with both visual and verbal signals when new aircraft are detected. Your unit alerts you with the spoken words, “Traffic, traffic” to get your eyes on the display right away. The Garmin display technology assesses data integrity from both ADS-B frequencies and displays the most accurate data. This cuts down on ghosts, duplicate targets and other false alarms.
GDL-39 GPS capabilities
The Garmin GDL-39 contains a WAAS (Wide Area Augmentation System) receiver for GPS location services. Garmin has been the #1 name in GPS technology for over 20 years. Since the company’s founding in 1989, Garmin has based its reputation on the delivery of fast, robust and error-free navigation information. The GDL-39 is no disappointment in this arena.