The week in the sky: 15,419 aircraft, one quiet Saturday and a Cessna in the top five

A steady week, with one sharp peak

Between Monday 28 September and Sunday 4 October our receivers logged 15,419 different aircraft near the 994 airports we keep an eye on. Counted per airport and per day, that adds up to 23,938 sightings, almost exactly the same as the week before (23,824). Corrected for the number of snapshots we took, activity was up 1.9 percent. In other words: a normal early-October week, without a storm, a strike or a holiday big enough to show up in the totals.

The shape of the week is familiar. Thursday 1 October was the busiest day with 3,773 aircraft, and Saturday 3 October the quietest with 2,909: a gap of 30 percent. The week before showed the same dip on Saturday (2,965). The Saturday lull is one of the most reliable patterns in our data: airlines thin out their schedules, business jets stay on the ground and flight schools are busy but small. Sunday recovers only partly; the real restart comes on Monday morning.

The Saturday dip is not a measurement artefact: we took the same number of snapshots on Saturday as on Thursday. The sky really was 30 percent emptier.

New York, San Francisco and Los Angeles lead; Amsterdam is Europe's number one

Ranked by the number of distinct aircraft we saw near the airport over the week, three of the big American gateways take the first three places, separated by only 33 aircraft. John F. Kennedy in New York tops the list with 601, San Francisco follows with 597 and Los Angeles with 568. Toronto Pearson is the first non-American airport in fourth place, and Las Vegas rounds off the top five.

Amsterdam Schiphol is the highest-ranked European airport, in sixth place with 472 aircraft, ahead of London Heathrow (405, eleventh). That order says more about our receivers than about the airports: Schiphol has very dense coverage in our network, and Heathrow's airspace is shared with Gatwick, Luton and Stansted, each of which appears separately in our list. Sydney (388) and Tokyo Haneda (345) are the only airports outside North America and Europe in the top fifteen.

Seen this way, San Francisco edges past New York: on an average snapshot there were 28 aircraft around SFO against 27 around JFK. We deliberately do not publish week-on-week changes per airport. With about three snapshots a day per airport, a swing of ten percent can be a real change or just the luck of the draw, and we would rather show you nothing than something we cannot stand behind.

Half of everything we see is American

Grouped by country, the United States accounts for 12,095 of the 23,938 sightings, just over half. That reflects both the size of American aviation and the fact that 300 of the 994 airports in our list are American. The United Kingdom (1,318), Australia (1,250) and Canada (1,068) follow at a distance. The Netherlands, with only five airports in the list, still reaches 525 sightings thanks to Schiphol.

Two movements stand out. Canada was down 13 percent on the week before, spread across its 36 airports rather than caused by one of them. And France was up 23 percent, with Germany, Japan, the Netherlands and Poland all between 10 and 16 percent higher. We do not know the cause of either shift from the data alone, and we will not guess. If the pattern holds next week, it becomes a story; if it does not, it was noise.

American, Delta and Southwest: three airlines above a thousand

We recognise an airline by the first three letters of the call sign its aircraft transmit. By that measure American Airlines (AAL) led the week with 1,097 sightings, followed closely by Delta (1,066) and Southwest (1,045). United is fourth with 827, and then there is a clear gap to JetBlue (522) and SkyWest (484), the regional carrier that flies for several of the big names. Ryanair, with 382, is the first non-American airline, ahead of British Airways (202), easyJet (195) and Lufthansa (182).

Note the tenth place: NetJets (EJA), the fractional-ownership business jet operator, was seen more often than Republic Airways, FedEx or British Airways. Its fleet of several hundred small jets is spread over dozens of airports, which is exactly the kind of traffic a per-airport sample picks up well. FedEx was one of the few names with a double-digit increase (+11 percent), as was Envoy Air (+18 percent) just outside this list. KLM, the home carrier of Schiphol, came in at 132 sightings, up 11 percent.

The fleet: Airbus narrowbodies just ahead of the 737, and a trainer in fifth

For 13,744 of the 15,419 aircraft, nine out of ten, we know the type. The single most-seen type is the Boeing 737-800 with 1,360 aircraft, followed by the Airbus A320 (954), the 737 MAX 8 (861) and the A321neo (795). Add the families together and the picture flips: the A320 family (A319, A320, A321 and their neo versions) reaches 3,181 aircraft, the 737 family 2,933. Widebodies make up a modest 1,583, led by the 767-300 (268), the 787-9 (253) and the 777-300ER (207).

And then there is the Cessna 172 in fifth place, with 643 different aircraft, more than the A321 or the A320neo. No airline flies it; it is the world's most-built trainer, and flight schools around busy airports fly it all day, every day. Its cousin, the Piper PA-28, sits in tenth place with 323. Together they are a reminder of what our data really is: not an airline timetable, but a picture of everything with a transponder that moves near an airport, from a Boeing 777 on its way to Tokyo to a student pilot practising circuits.

The United States and the United Kingdom this week

At the 300 American airports in our list we counted 12,095 sightings, almost level with the week before (12,204), from 7,630 distinct aircraft. Seen from inside the United States the airline order changes: Southwest (1,045) edges past American (1,039), with Delta at 1,008 and United at 789. American leads the global ranking only because of its flights abroad. The American fleet is also where the Cessna 172 earns its fifth place worldwide: 464 of the 643 Skyhawks we saw were near American airports, more than the 450 Boeing 737 MAX 8s there.

Across the Atlantic, the 29 British airports in our list produced 1,318 sightings, up 2.5 percent, from 929 distinct aircraft. Heathrow leads with 405, Gatwick follows with 248 and Manchester with 140; Edinburgh (85), Stansted (68) and East Midlands (57) complete the top six. easyJet (169) was seen more often than British Airways (151), with Ryanair (85) and Jet2 (81, up from 57) behind them. The British fleet is a near-even split: 121 Boeing 737-800s against 113 Airbus A320s, with 82 A320neos and 78 A321neos closing in.

What to watch next week

Three things. Whether Canada's 13 percent drop and France's 23 percent rise persist, which would make them real rather than sampling noise. Whether the Saturday dip stays at 30 percent as the autumn schedules settle in. And whether the gap between the A320 and 737 families, now 248 aircraft in Airbus's favour, widens as more A321neos enter service. The next article covers week 41, 5 to 11 October.