Contributing ADS-B Data: Why It Helps

Summary: What feeding an ADS-B receiver involves, what MLAT adds, why UK coverage gaps matter for military tracking, and the three ways to start.

The aircraft on the UKAFG map come from the airplanes.live network: a few thousand people running a small receiver at home, each covering their own patch of sky. The map can only show what somebody, somewhere, can hear. If you run a receiver, you widen that.

What Feeding Actually Is

Aircraft broadcast their identity, and usually their position, on 1090 MHz. A receiver the size of a paperback picks those broadcasts up, a small program on a Raspberry Pi (or any spare computer) decodes them, and a feed client passes them to airplanes.live, which merges every feeder into the picture you see on the map. Nothing is transmitted, and it runs unattended once it is set up.

Why MLAT Is the Part That Matters Here

Plenty of aircraft, military ones especially, transmit a Mode S identity but no position. On their own, those aircraft cannot be placed on a map at all.

Multilateration (MLAT) fills that gap. When four or more receivers hear the same aircraft, the network compares the fractions of a microsecond between each receiver hearing it and works out where it must have been. That only works where receiver coverage overlaps, which is why another receiver in a thin area does more than another one in a well-covered city.

• It needs overlapping coverage — four or more receivers hearing the same aircraft at once.
• It needs your antenna position to be accurate. The calculation works in microseconds, so a position that is out by a street corner degrades everyone’s results, not just yours.
• It rewards height and a clear view far more than expensive equipment.

For UKAFG that is the difference between a military aircraft appearing on the map and being invisible. Our military tracking, the activity board and the frequency work behind it all lean on positions that are often MLAT-derived — see Military Flight Filters & the Activity Board.

Where the UK Is Thin

• Low-level traffic away from the big airports: a receiver only sees what is above its horizon, so valleys, coastlines and training areas need somebody local.
• Scotland, the north Pennines, mid-Wales, the south-west peninsula and the coasts either side of the North Sea and Irish Sea have far fewer receivers than the south-east.
• Offshore and over the sea, where military activity is routine and there is nowhere to put a receiver except the nearest coast.

What You Get Back

• Your own statistics page showing what your receiver is hearing, and how far.
• A local map of your own coverage, which is oddly addictive.
• Your data on the UKAFG map, including aircraft only your receiver can hear.
• You can feed several networks at once from one receiver — adding airplanes.live does not mean giving anything up.

Three Ways to Start

• You already have a receiver running PiAware, ADSBexchange or similar: add airplanes.live alongside it in a few minutes — see Feeding From a Receiver You Already Have.
• Starting from nothing: the shopping list is in ADS-B Receiver Hardware: What You Need.
• Hardware in hand: their ready-made SD card image does the work for you — see Setting Up a Receiver With the airplanes.live Image.

UKAFG is not affiliated with airplanes.live. This section is a plain-English walk-through for members who want to help; their own guides at airplanes.live/get-started are the authority, and worth checking, as commands, images and hardware move on.