Tracking military aircraft online: what you can see and where it ends

A tanker flies figure eights over northern Germany for hours, a transport comes in from across the Atlantic to an air base, an AWACS circles over Eastern Europe: on flight tracker maps, military aircraft are long since no rare sight. At the same time, the very jet you can hear thundering overhead is often missing. This guide explains what you can actually see when tracking military aircraft online, which tools suit the job, how to identify military flights reliably and where the technical, legal and ethical limits lie.

Tracking military aircraft: the short answer

You only see a military aircraft online if its transponder emits civil signals and enough receivers on the ground hear them. If the aircraft transmits ADS-B with a GPS position, it appears on practically every map. If it only sends Mode S without a position, you need MLAT, meaning location via time differences between several receivers. And even then, the tracking service decides whether to show the aircraft or filter it out.

A fairly clear pattern follows: large aircraft in normal airspace – tankers, transports, reconnaissance aircraft, government planes – are often easy to track. Fighter jets on exercises, helicopters flying low and anything deliberately operating inconspicuously, on the other hand, you often don’t see at all or only in fragments.

What is technically visible at all

The basics are the same as with airliners. An aircraft transponder responds to interrogations from radar stations and also sends messages on its own. Four types of signal matter for you as an observer:

• ADS-B (1090 ES): The aircraft broadcasts its own GPS position, altitude, speed and identification. If you receive that, the aircraft sits precisely on the map.
• Mode S without position: The aircraft sends its unique 24-bit address (the hex code) and altitude, but no location. Only MLAT turns that into a position – provided at least four synchronized receivers hear the signal.
• Mode A/C: Just squawk code and altitude, without a unique identifier. Such targets don’t appear on most maps at all, because they can’t be assigned to an aircraft.
• Military Modes 4 and 5: The identification friend or foe system of NATO forces. Mode 5 is essentially an encrypted variant of Mode S with GPS position. Without the matching key, nothing can be done with it – no hobby receiver decodes this data.

What ends up on the map for military aircraft is therefore always only the civil portion of their radio traffic. How the modes work in detail is explained in the article Transponder Modes A, C and S.

Signal	What you see	Typical for	Accuracy
ADS-B with position	Position, altitude, heading, callsign, hex code	Tankers, transports, government aircraft in civil airspace	very high
Mode S without position	Hex code and altitude, position only via MLAT	Many military aircraft that don’t enable ADS-B	Depends on receiver density, often coarser
Mode A/C	Squawk and altitude, no identification	Older equipment or reduced transponder operation	Mostly invisible on maps
Mode 4/5	nothing	Military identification	Not receivable

Why military aircraft are missing on some maps

If a known military flight doesn’t show up in your favorite app, it can come down to three things. General reasons for missing aircraft are also explained in the article Why an aircraft doesn’t show up on the flight tracker.

1. The transponder sends nothing usable

Armed forces decide for themselves how to use their transponders. In civilian-controlled airspace, for example on ferry or transport flights over Europe, many aircraft transmit as normal. In training areas, on operations or on sensitive missions, it looks different. The result: a Eurofighter that rolls across the map with a callsign in the morning can vanish without a trace half an hour later even though it is still flying.

2. There are too few receivers

MLAT needs dense receiver networks. Over metropolitan areas that works well, over the North Sea, mountains and sparsely populated training areas often not. But that is exactly where exercises like to take place. At low altitude, reception also drops out because terrain and the curvature of the earth block the line of sight to the antenna.

3. The service filters

Commercial providers such as Flightradar24 say they hide certain aircraft for security and privacy reasons. A well-known example: at the request of Japan’s defense ministry, the position of the Japanese government aircraft has no longer been shown since 2014. Then there are programs like the US LADD, through which owners can have their data blocked at services that use FAA data. How the big apps differ is shown in the flight tracker app comparison.

The tools: from the app to your own receiver

For military flights, a different toolbox pays off than for the vacation jet. Roughly speaking, there are four categories.

Tool	Examples	Filtering behavior	Strength	Weakness
Commercial flight tracker apps	Flightradar24, FlightAware, AirNav RadarBox	hide some aircraft	Convenient, good type and photo data	Gaps especially for military and government
Unfiltered community trackers	ADS-B Exchange, adsb.fi, adsb.lol, airplanes.live	say they show all received data	Maximum completeness, often with military flagging	Plainer interface, less comfort
Your own receiver	Raspberry Pi or ready-made receiver with tar1090	none	Raw data straight from your surroundings, nothing in between	Only the range of your antenna
Databases	Scramble, hex lists from hobby projects	–	Matching hex code, serial and unit	No live position

Unfiltered community trackers

For military flights, the community networks are the first stop. ADS-B Exchange is the best-known one. Alongside it, adsb.fi, adsb.lol and airplanes.live have established themselves, also relying on unfiltered data. Many of these maps are built on the tar1090 interface and pull additional information from databases in which known military aircraft are flagged. That way you can have only military traffic displayed. Some hobby sites such as ads-b.nl build on this and specialize entirely in military flights.

Your own receiver

The most direct way is with your own receiver: an SDR stick, an antenna and a small computer are enough. You then see everything your antenna hears – including aircraft that commercial services filter out. How to get started is described in the guides Build your own ADS-B receiver and Flight tracking on your PC with tar1090. If you pass your data on to community networks, others benefit too – and more receivers mean better MLAT coverage for everyone.

Databases

Live trackers tell you where something is flying. Databases tell you what it is. The spotter database Scramble has been collecting data on military aircraft, units and bases for decades. Anyone who wants to match a hex address or serial cleanly to a squadron can hardly avoid sources like these.

Recognizing military flights on the map

Not every gray dot without an airline logo is a military flight, and not every military flight looks military. These features help you classify it:

• Callsign: Many armed forces have their own ICAO designators. The German Air Force flies as GAF (“German Air Force”); the Army and Navy have their own abbreviations, GAM and GNY. The Royal Air Force uses ASCOT (code RRR) for air transport, and US Air Force Air Mobility Command transports operate as REACH. There are also many mission-specific callsigns that change.
• Aircraft type: Type codes for the Airbus A400M, A330 MRTT, Boeing C-17, KC-135, E-3 Sentry or P-8 Poseidon often give it all away.
• Hex address: Each country gets its own address block, and armed forces often use their own sub-ranges within it. How to look things up by hex code is shown in the guide Tracking an aircraft by registration or hex code.
• Serial: Military aircraft don’t carry a civil registration but national serial numbers. For the Bundeswehr, these are the familiar numbers with a plus sign – more on that under Serials of Bundeswehr aircraft, and for US aircraft under US military serials.
• Flight pattern: Oval racetracks at high altitude point to tankers or reconnaissance aircraft, long loops over the sea to maritime patrol aircraft. How to recognize such types in the sky as well is covered in Recognizing AWACS and reconnaissance aircraft and Recognizing military transports.

Watch out for mix-ups: some civilian airlines fly on behalf of armed forces, such as charter companies for troop transport like Omni Air International. Conversely, AirTanker operates tanker aircraft for the British air force. On the map, the line between “military” and “civil” isn’t always sharp.

The limits: what is never complete online

Keep three effects in mind at all times:

• An empty map doesn’t mean an empty sky. If nothing is displayed, is nothing flying? Wrong. With military flights especially, absence from the map is the rule, not the exception.
• MLAT is an estimate. Positions from time differences jump, lag behind or drop out as soon as a receiver fails. For the question “is it about to come in?” that’s enough, for exact flight paths it isn’t.
• Delay: Depending on the service, a few seconds pass between reception and display. With fast jets on airfield approach, that can make the difference between having your camera up in time or not.

A special case is emergency codes: military aircraft also set the well-known squawks in a real emergency. What 7500, 7600 and 7700 mean is explained in the article Squawk codes 7500, 7600 and 7700.

Legal matters and tact

Looking at publicly accessible tracking sites is everyday life for millions of people. But as soon as you use your own equipment and pass on data, a closer look is worthwhile: what applies to receiving and sharing ADS-B data in Germany, Austria and Switzerland is summarized in Receiving ADS-B data: the legal situation. Photography at barracks and air bases has its own rules – see Photographing military airbases. And if you spot abroad, check the legal situation abroad beforehand; in some countries, receivers or photos of military installations are quickly seen as a security problem.

Regardless of the law, there is also a question of decency. If you spot an aircraft in an operational area or a sensitive transport, you don’t have to post it to the world in real time. Spotters don’t need live situation maps, but the information on when a plane is expected back at the airfield. It’s best to share photos and sightings with some delay and without speculation about the purpose of operations.

From tracker to photo: using the data at the airfield

Military tracking gets you the most when you combine it with a spotting trip. The process is always similar.

For specific airfields, the guides to Geilenkirchen and the AWACS, to Wunstorf air base with the A400M and to Ramstein Air Base help. At the Teveren spotters’ hill you’ll find a fixed location with a view of the runway: Teveren spotters’ hill in Geilenkirchen. If fighter jets interest you, take a look at Spotting Eurofighters in Germany – there, because of the gaps, tracking plays a smaller role than knowing the airfield. If you want to match your photos against logs afterward, you’ll find the approach in Matching sightings against ADS-B logs.

Conclusion

Tracking military aircraft online is not a look behind the curtain, but a look at the civil part of their radio traffic. Tankers, transports, reconnaissance aircraft and government aircraft are often easy to see, fighter jets and operations mostly not. If you want more, combine an unfiltered community tracker with a good database and, ideally, your own receiver. And anyone who uses the data at the fence instead of broadcasting it live ends up with the better pictures – and the scene with a good reputation.