Planes already fly the shortest path. On a sphere the most-direct route between two cities is a “great circle,” and that genuinely shortest line only looks curved when you draw it on a flat map. Mercator maps stretch the globe into a rectangle and distort distances badly near the poles, so the efficient arc appears bent. Beyond geometry, four real-world factors nudge the actual track: jet-stream winds, storm avoidance, airspace permissions and closures, and ETOPS diversion-airport rules over oceans and poles.
Updated June 2026 · HappyFares
If you’ve ever watched the moving-map screen on a Delhi–San Francisco flight, you’ve probably wondered why the little plane icon arcs up toward the Arctic instead of cutting straight across. It looks like a detour. It isn’t.
The curve is the shortest route — your eyes are just being fooled by a flat map of a round planet. Below, we’ll unpack the geometry first, then the four real-world reasons actual flight paths bend even more, with the India-specific picture for 2026.
Why does the shortest route look curved on a map?
It comes down to the difference between a globe and a flat map. The genuinely shortest path between two points on a sphere is a great circle — the line you’d get by slicing the planet through both cities and its centre. That path is the most direct route there is. The catch: a Mercator map flattens the round Earth into a rectangle, and flattening a globe stretches distances, most severely near the poles. So the truly direct route shows up as an arc on paper.
Stretch a rubber band over a globe between two far-apart cities and you’ll see the same arc in the real world. The string sits straight on the sphere; it only photographs as a curve when you press the globe flat.
Isn’t a straight line on the map shorter?
No — and this is the part that trips people up. A “straight” line on a Mercator map is a rhumb line: a path of constant compass bearing. It looks shorter because it looks straight, but on the actual sphere it’s longer than the great circle. That’s exactly why high-latitude routes look so circuitous on paper yet are the efficient choice. The map is lying about distance; the great circle isn’t.
Quick gut-check: the great-circle distance between Delhi (DEL) and San Francisco (SFO) is roughly 12,400 km, about 6,700 nautical miles. The path actually flown is longer than that straight-line figure — for reasons we’ll get to next.
What actually bends a flight path beyond geometry?
Geometry sets the ideal line; the real world bends it. Beyond the great circle itself, four factors shape the track a plane actually flies: jet-stream winds, weather and storm-cell avoidance, airspace and overflight permissions (including closures and no-fly zones), and ETOPS diversion-airport limits over oceans and poles. None of these is a “detour for fun” — each trades a few extra kilometres for time, fuel, or safety.
Think of it as the difference between the line a hiker draws on a map and the trail they actually walk around a cliff, a river, and a closed bridge. The destination’s the same; the path respects the terrain.
How do jet streams change the route?
Jet streams are fast, high-altitude winds that blow west to east, and at cruise their core can exceed about 400 km/h (250 mph). That’s a river of air a plane can either ride or fight. Eastbound flights often slot into the jet stream to grab the tailwind, which can save significant time and fuel. Westbound flights do the opposite — they route around the strongest core to dodge the headwind.
One real consequence you may have noticed: on the very same long-haul route, the westbound (return) leg can run noticeably longer than the eastbound outbound leg, purely because of headwinds and the detours taken to avoid them.
What about storms and weather?
Thunderstorms get a wide berth. Pilots reroute around convective storm cells using onboard weather radar and air-traffic-control clearance, keeping a safety buffer from the tallest cells. These are typically small, local deviations rather than a whole new routing — and over India during the monsoon they’re common, which is why your moving map sometimes shows a gentle zig-zag with no apparent reason. There’s a reason; it’s just a towering cumulonimbus 200-odd kilometres ahead that the crew is steering clear of.
How do airspace rules and closures bend the path?
Airspace is sovereign, and that dictates a lot. Every country controls its own skies, so routing depends on overflight permissions, international ICAO and ETOPS standards, and NOTAMs (notices that flag temporary airspace closures or no-fly zones). For Indian flights, these levers are coordinated by the DGCA, the AAI and airport operators, and each airline’s own dispatch team — not by a passenger-rights regulator, and not by the FAA or EASA, which govern other countries’ flights, not India’s.
When a neighbour closes its airspace, the great circle can become unflyable and the route has to swing around the gap. As of mid-2026, that’s exactly the binding constraint for Indian carriers flying west — covered in its own section below.
What is ETOPS, and is flying on one engine safe?
ETOPS is the rule that keeps a back-up airport within reach. ETOPS — Extended-range Twin-engine Operations — requires a twin-engine jet to stay within a certified single-engine flying time of a suitable diversion airport. That requirement nudges oceanic and polar routes to keep an alternate field within range, which can curve the track. Modern widebodies like the Airbus A350, Boeing 787 and Boeing 777 carry high ETOPS ratings, and those ratings are what make near-direct ocean crossings possible.
And yes — flying on one engine is safe and trained-for. Commercial twinjets are certified to keep flying and to land safely on a single engine. An engine failure is rare, and ETOPS diversion planning exists precisely so the crew can reach an alternate airport if it ever happens. (ETOPS ratings are granted per aircraft type and per operator, and they vary, so we won’t quote a specific minutes figure as gospel.)
Has the single-engine plan ever been used for real?
It has — and it worked as designed. In June 2023, Air India flight AI173 (Delhi–San Francisco, a Boeing 777-200LR) developed an engine problem over the Russian Far East and diverted to Magadan. The roughly 216 passengers were sheltered locally, and a relief 777 was dispatched from Mumbai to complete the journey. The certified single-engine diversion did exactly what it’s built to do: get everyone to a safe airport. It’s a reassuring example of the system working, not a scary one.
Why does Delhi–San Francisco fly over the North Pole?
Because the pole is the shortest way. Air India became the first Indian airline to operate a commercial polar route — over the North Pole — on Delhi–San Francisco (AI173) on 15 August 2019, crossing high northern latitudes precisely because that path is the great circle between the two cities. On a globe, the line from northern India to California rides up and over the Arctic. It looks wild on a flat map and entirely sensible on a ball.
The 2019 launch came with neat efficiency gains for that era — trimming flight time and saving fuel versus the older routing. We’d flag those 2019-vintage savings as exactly that: 2019 numbers, from before the airspace picture over India’s west changed. Which brings us to the thing that’s reshaped these routes since.
How does the Pakistan airspace closure change Indian routes in 2026?
It’s the wall Indian carriers now have to route around going west. Since spring 2025, Pakistan has closed its airspace to Indian carriers, and the ban has been extended into 2026 (reported via NOTAM to around 24 July 2026 — confirm the current status before you fly). With the direct western corridor shut, some Delhi–North America services are now routed south with a refuelling stop, for example via Vienna or Copenhagen, adding roughly three hours. Treat any precise total distance or time as approximate and check the current schedule.
Reported, point-in-time figures from mid-2026 put the cost in real terms: an estimated annual hit of around USD 600 million for Air India, fuel costs up to roughly 29% higher on affected routes, and about three extra hours each way on some services. These are “as of mid-2026” press figures, not fixed constants — they move as routings and schedules are adjusted.
Wait — don’t airlines avoid Russia too?
Not Indian ones, and this is a crucial India-specific distinction. You may have read that “airlines take the long way around Russia.” That’s true for US, UK, EU, Canadian and Japanese carriers, which are barred from Russian airspace. It is not true for India. India didn’t ban Russian aircraft, so Russia didn’t ban India — which means Air India can still overfly Russia in 2026. For Indian flights heading west, Russia is the open relief valve that keeps the northerly and polar options alive, while Pakistan is the closed wall. Don’t mix up the two: the “avoid Russia” line is imported from Western aviation and simply doesn’t apply here.
Air India’s international network is also being rationalised through 2026, with some long-haul routes temporarily suspended or trimmed. Treat those as temporary and confirm the current schedule against Air India’s own newsroom before you book.
Common Questions
Do planes really fly the shortest route?
Yes. Airlines fly as close to the great-circle (genuinely shortest) path as winds, weather, airspace and ETOPS allow. The route looks curved only because a flat Mercator map distorts distances, most severely near the poles. The actual track may be longer than the pure great circle once jet streams and closed airspace are factored in.
Why is my return flight longer than the outbound?
Jet streams. These high-altitude winds blow west to east and can exceed about 400 km/h at cruise. Eastbound flights ride the tailwind to save time and fuel, while westbound flights route around the headwind. On the same long-haul route, that makes the westbound return leg noticeably longer than the eastbound outbound leg.
Is it safe to fly over the North Pole?
Yes. Polar routes are flown because they’re the great circle — the shortest path — between cities like Delhi and San Francisco. Air India operated India’s first commercial polar flight on Delhi–San Francisco on 15 August 2019. ETOPS rules ensure a suitable diversion airport stays within certified single-engine reach throughout the crossing.
Can a plane fly safely on one engine?
Yes. Commercial twinjets are certified to keep flying and to land safely on a single engine, and an engine failure is rare and trained-for. In June 2023, Air India’s AI173 diverted to Magadan after an engine problem; the roughly 216 passengers were sheltered locally and a relief aircraft completed the trip. The single-engine diversion worked as designed.
Who decides how an Indian flight is routed?
For Indian flights, routing is governed by airspace sovereignty, international ICAO and ETOPS standards, and NOTAMs flagging closures — coordinated by the DGCA, the AAI and airport operators, and each airline’s dispatch. The FAA and EASA govern other countries’ flights, not India’s. As of mid-2026, the binding constraint heading west is the Pakistan airspace closure.
Does the Delhi–San Francisco polar route still fly the same way?
Not exactly. The 2019 polar routing has been disrupted by the Pakistan airspace closure, which at times forces a southern routing with a refuelling stop (for example via Vienna or Copenhagen), adding roughly three hours. Russia remains open to Air India, so the northerly option survives — but confirm the current schedule before you fly.
Plan around the longer routes
Knowing why a route curves won’t shorten your flight, but it does explain why fares and timings shift when airspace changes. When western corridors close and routings stretch, prices and schedules move with them — so it pays to compare before you book. You can search and compare live flight options across airlines on HappyFares to find the trip that actually fits your day.
Want to go deeper? Read Why Do Planes Cruise at 35,000 Feet?, see how a single short hop is timed in Delhi to Dubai: Distance, Flight Time & Airlines (2026), understand your rights when a flight is diverted to another city, and check which sectors travellers search most in our Most-Searched Indian Flight Routes 2026 analysis.
Disclaimer: Airspace rules, routings, ETOPS ratings and airline schedules are indicative and change frequently. Figures here are point-in-time and where noted are “reported” or “as of mid-2026.” Confirm the current status with the airline, the DGCA or BCAS before relying on any detail for travel planning.
