Understanding ADS-B Traffic

Understanding ADS-B Traffic

Understanding ADS-B Traffic

Stratux shows you nearby aircraft on your EFB. Here’s what you’re seeing and why.

Two Types of Traffic

1090 MHz (Mode S / ADS-B Out)

This is the international standard. Aircraft equipped with ADS-B Out broadcast their position directly, and Stratux picks it up.

What you’ll see: - Airliners (always) - ADS-B Out equipped GA aircraft - Works on the ground - Works anywhere, even over water

978 MHz (UAT / TIS-B)

This is US-only and more complex. The FAA’s ground network does two things:

  1. Rebroadcasts ADS-B Out traffic it sees
  2. Uplinks radar targets (TIS-B) for aircraft that triggered the system

What you’ll see: - Traffic the ground towers see - Only works with line-of-sight to a tower (~1,000+ feet AGL) - Only in US

Why Don’t I See All Traffic?

Several reasons:

On the Ground

  • 978 MHz requires altitude for line-of-sight
  • 1090 MHz works, but only shows ADS-B Out aircraft nearby

In the Air (but limited traffic)

  • No ADS-B Out nearby — TIS-B only activates when an ADS-B Out aircraft is close enough to “light up” the towers
  • Not in tower coverage — rural areas may have gaps
  • Below radar coverage — low altitude in valleys

The TIS-B Limitation

TIS-B (Traffic Information Service - Broadcast) only works when you’re near an ADS-B Out equipped aircraft. The FAA designed it this way — the towers only send traffic data to the area around ADS-B Out aircraft.

Translation: If you’re the only non-ADS-B-Out aircraft in the area, you might not see much traffic even though you’re receiving.

Traffic Display Limitations

Your EFB app may also filter what it shows:

App Limitation
ForeFlight Only shows traffic within ±3,500 feet of your altitude
Most apps Have similar vertical filters

If you know traffic is nearby but don’t see it, check your EFB settings.

The “Ghost” Aircraft (TIS-B Shadow)

Sometimes you’ll see a target following right behind you at your altitude. This is your own radar return being rebroadcast.

Fix: 1. Go to http://192.168.10.1 → Traffic page while flying 2. Find the target at your altitude, 0.1 miles away 3. Note its hex code 4. Enter that code in Settings → “Own aircraft hex code”

If you have ADS-B Out or Mode S, you can also look up your hex code at FAA Registry.

Tower Coverage Map

See where the ADS-B ground towers are: towers.stratux.me

For traffic issues, see Troubleshooting Traffic.

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