Here’s a fact that sounds wrong the first time you hear it: the great-circle route — the provably shortest path between two airports on a sphere — is almost never what your flight actually flies.
Every flight tracker, every mileage program, every “distance” you’ve ever been shown for a flight is a great-circle number. It’s the aviation industry’s official fiction. The real path is longer. Usually much longer.
I can put numbers on this, because I recently rebuilt my flights page to compute distances from actual ADS-B position data instead of airport coordinates. For 107 of my 113 lifetime flights I now have the real flown track. The result:
- On average, my flights flew 12.9% farther than the great circle.
- Across everything, that’s 11,400 extra miles my mileage apps never told me about — the gap between 155,589 great-circle miles and 167,015 actually flown.
- The worst offender flew 44% over. The best was just 0.4% over — and where those two flights happened tells you almost the whole story.
The extremes
Here are my ten biggest offenders — every flight ranked by how far its actual ADS-B track exceeded the great-circle distance:
| # | Flight | Date | Route | Great circle | Flown (ADS-B) | Over |
|---|---|---|---|---|---|---|
| 1 | NH32 | 2025-06-24 | ITM → HND | 251 mi | 362 mi | +44.2% |
| 2 | CX961 | 2025-07-24 | HGH → HKG | 680 mi | 940 mi | +38.2% |
| 3 | AA4568 | 2025-03-02 | PIT → JFK | 339 mi | 458 mi | +35.1% |
| 4 | GJ8738 | 2023-04-15 | SZX → HGH | 665 mi | 879 mi | +32.2% |
| 5 | CX302 | 2026-07-06 | HKG → PVG | 780 mi | 1,027 mi | +31.7% |
| 6 | DL5794 | 2024-01-12 | JFK → PIT | 339 mi | 440 mi | +29.8% |
| 7 | 9C8921 | 2023-06-07 | PVG → HKG | 780 mi | 1,008 mi | +29.2% |
| 8 | UA408 | 2025-05-22 | EWR → IAD | 212 mi | 273 mi | +28.8% |
| 9 | AA4734 | 2025-03-07 | JFK → PIT | 339 mi | 436 mi | +28.6% |
| 10 | KE882 | 2026-03-31 | PVG → ICN | 511 mi | 656 mi | +28.4% |
Two patterns jump out immediately: short hops (Osaka–Tokyo, the New York–Pittsburgh cluster, Newark–Washington) and Chinese coastal routes (Hong Kong, Shanghai, Hangzhou, Shenzhen in every combination). Both are explained below.
The record: NH32, Osaka Itami → Tokyo Haneda, +44.2%. Great circle: 251 mi. Actually flown: 362 mi. This is a 250-mile hop, and that’s exactly why the percentage explodes — departure and arrival procedures are a roughly fixed overhead, and on a short flight they are the flight. You don’t take off from Itami and point at Haneda; you fly a published departure, get vectored around Osaka’s terminal airspace, cruise for twenty minutes, then join an arrival stream that snakes across Tokyo Bay. The overhead that disappears into rounding error on a long-haul is nearly half the trip here.
The runners-up are all Chinese coastal routes. Hangzhou → Hong Kong at +38%, my Hong Kong → Shanghai flights clustered between +27% and +32%. These aren’t weather anomalies — the same routes come in long every single time, because in Chinese airspace you fly published airways between fixed waypoints, full stop. The direct line from Hong Kong to Shanghai crosses airspace you simply don’t get to use. Every HKG–PVG flight dutifully tracks up the coast, and every one of them logs roughly 1,000 miles for a 780-mile city pair.
The exception that proves the rule: TN102, Auckland → Papeete, +0.4%. Over the empty South Pacific there are no airways to follow, no military zones to dodge, no arrival queues. The 787 simply pointed at Tahiti and flew the sphere’s geodesic, 2,543 miles of it, four miles over the theoretical minimum. When nothing stops a plane from flying the great circle, it does.
So why doesn’t everyone fly like TN102?
1. The sky is a road network, not an open field. Most of the world’s airspace is organized into airways — published corridors between named waypoints. Your flight plan is a sequence of these, filed and approved before departure. Some regions (the North Atlantic, parts of the US) have loosened into “free route” airspace; much of Asia has not. If the airway bends, you bend.
2. Wind beats distance. The shortest path is not the fastest or cheapest flight. A jet stream tailwind of 100+ knots is worth far more than a few dozen miles of track. Eastbound trans-Pacific flights deliberately swing south or north to ride the jet; westbound flights detour to avoid it. Dispatchers optimize a cost function of time and fuel — distance is just one input. A longer route that lands earlier wins.
3. Procedures bracket every flight. SIDs and STARs — standard instrument departures and arrivals — exist so that hundreds of flights an hour don’t converge on an airport from random directions. They add miles by design, and runway direction adds more: land to the south on a field north of the city and you’ll overfly, turn back, and line up. Fixed overhead, every flight, both ends.
4. Weather, the day-of tax. Thunderstorm cells, typhoons, turbulence reports — all bought with track miles. My own record-setting CX302 into Shanghai carried a remark about bad weather at Chek Lap Kok and paid +31.7% that day.
5. Politics and money. Overflight permissions, country-by-country navigation fees, and sanctions redraw routes wholesale — the closure of Russian airspace added hours to Europe–Asia flights, no meteorology involved. Airlines also route around expensive airspace when fuel is cheaper than fees.
The six flights I couldn’t measure
Of my 113 flights, six have no usable track at all and are counted at their great-circle minimum. All six are mainland-China domestic flights, flown between May 2021 and August 2023 — four Shanghai–Chongqing legs, one Shenzhen–Hangzhou, one Guangzhou–Hangzhou. That clustering is not a coincidence.
Community trackers like ADS-B Exchange depend on volunteers running ground receivers, and through 2020 mainland coverage was genuinely good — both of my July 2020 domestic flights came back with essentially complete tracks (one at 100% coverage, one at 91%). Then, around 2021, Chinese authorities cracked down on hobbyist ADS-B receivers on national-security grounds, and crowd-sourced coverage over the mainland collapsed. My 2021 and 2022 flights exist in the archives only as scraps: a distant receiver catching a few minutes of cruise, then nothing. One flight I checked appears as 58 position reports covering thirteen minutes of a two-hour trip.
I tried hard to salvage these. For a couple of them I could stitch fragments into a partial reconstruction, but they failed my own sanity checks — one came out 48% over the great circle, which might even be true (a typhoon was active in East China that week), but “might” isn’t a number I’ll put in the dataset. The alternatives dried up too: Flightradar24 does have these flights — it never depended on the volunteer receivers — but its history is subscription-tiered and my plan reaches back one year, not five. adsb.lol’s open archive only begins around 2024. Coverage over the mainland has since partially recovered through satellite ADS-B and new receivers, which is why my recent Chinese flights track fine; the 2021–2023 gap, though, is simply lost history.
So those six are honest floors: the plane certainly flew farther than the number I’m using.
The slightly unfortunate part
Every frequent-flyer program on earth credits you great-circle miles. Flighty, Umetrip, your airline’s app — all display great-circle distance (I checked Umetrip against my own tracks: its kilometers match the great circle almost exactly). By the industry’s own bookkeeping, I’ve flown 155,589 miles. My actual tracks say 167,015 and counting, and that number is a floor — the six flights I couldn’t recover tracks for are counted at their great-circle minimum, and coverage gaps inside tracked flights are bridged with straight lines. Eleven thousand miles, genuinely flown, that no ledger will ever credit.
So the shortest-path number everyone quotes is really a lower bound nobody achieves — except, apparently, one 787 alone over the South Pacific with nowhere to be vectored and nothing in the way.
The great circle isn’t a route. It’s a promise the sky can’t keep.