Why is a military plane circling? Tankers, AWACS and spy planes on station

You open a flight tracker and see an aircraft drawing the same long oval, over and over, for hours, far from any airport. If it is an airliner, it is waiting to land: see holding patterns. If it is military, it is on station: doing its job in one piece of sky.

Tankers: waiting for the aircraft they refuel

Air-to-air refuelling tankers carry fuel for other aircraft: fighters, transports, surveillance aircraft. They meet them at a published place and height, and fly laps there while the receivers come and go. In the US, the FAA's rules describe a standard refuelling anchor as a left-hand racetrack with legs of at least 50 NM, normally at least 20 NM apart, flown within a block of heights, and allow a tanker to wait in an orbit until its receivers arrive. The UK publishes 14 air-to-air refuelling areas, some always available and others opened by notice, at heights from 2,000 ft up to 29,000 ft.

The tankers you are most likely to see:

The A330 MRTT carries up to 111 tonnes of fuel, Airbus says, enough to stay on station far from base for hours.

Surveillance aircraft: watching an area

Early-warning and reconnaissance aircraft also fly long orbits, because their job is to watch one area for as long as possible:

• E-3 Sentry (AWACS), with the large rotating radar dome. NATO owns and flies 14 of its own from Geilenkirchen, in Germany; each operates above 30,000 ft for more than 10 hours, and one can watch more than 312,000 square kilometres.
• E-7 Wedgetail, a Boeing 737 with a radar on its back. Australia flies six; the RAF's first arrived at Lossiemouth in May 2026.
• RC-135 reconnaissance jets of the US Air Force's 55th Wing, which pick up and locate signals. Only two of the RC-135U Combat Sent version exist; the RAF also flies three of the RC-135W Rivet Joint.
• P-8 Poseidon maritime patrol aircraft, built on the Boeing 737, which orbit over the sea. The RAF flies nine from Lossiemouth.
• Global Hawk and its maritime version, the Triton, uncrewed aircraft that fly far above airliners; NATO flies five of its own from Sigonella, in Sicily. See the highest-flying aircraft.

What it looks like on a flight tracker

A tanker's station looks like a stretched oval, often tens of miles long, flown at one height. Of the tankers FlyScout has recorded on station, most flew between about 14,000 and 29,000 ft. Surveillance orbits look much the same. Both last far longer than an airliner's hold, and neither is near an airport.

FlyScout's rule looks only at military aircraft of the types built for these jobs, so a trainer's afternoon in the local area is not reported. It counts an aircraft as on station when it has flown at least two and a half laps of one area, above 8,000 ft. It measures the laps, the time, the height and the size of the area, and names the role, tanker or surveillance. It never says whom a tanker was there for, because the track does not show it.

Between 20 September and 16 October 2026, FlyScout recorded 78 military aircraft on station: 67 tankers and 10 surveillance aircraft. The KC-135 was the most common, with 32, ahead of Airbus A330 tankers (19) and Boeing 767 tankers (17). The surveillance aircraft included NATO E-3 Sentries over Spain, a US Air Force RC-135, P-8 Poseidons off Florida, and an E-7 Wedgetail over south-eastern Australia.

Why you can see them at all

Military aircraft fly in the same skies as airliners, and the rules that let controllers see airliners mostly apply to them too:

• In the US, an aircraft with ADS-B must transmit at all times, unless the FAA authorises otherwise for sensitive national defence, security, intelligence or law enforcement missions.
• In Europe, transport-type state aircraft had to carry transponders meeting the full standard, ADS-B included, from December 2020, with exceptions.
• The UK's Ministry of Defence has said its aircraft must use their Mode S transponders when flying alongside civil traffic, and that open-source tracking is a by-product of that. When they are kept apart from civil traffic, they can switch Mode S off.

Tankers and large surveillance aircraft spend much of their time among civil traffic, which is why they appear on trackers far more often than fighters.

What you see is only part of the picture. Aircraft on operations can switch their broadcasts off, and some trackers hide certain military aircraft. Networks that show everything they receive, such as ADSB.lol, show more of them: see how to track military aircraft.

Where tankers and surveillance aircraft are often seen

Between 20 September and 16 October 2026, the most frequent place was the sky near Dubai and Abu Dhabi, with 26 aircraft on station, 23 of them KC-135s, followed by the United States, France and Spain. The tanker in the example took off from Istres, near Marseille, the base of France's A330 tankers, and flew north to its racetrack near Châteauroux. These places change as exercises and operations move; the pattern stays the same.