Mystery: Why Is My Korean Air Flight So Long?

Filed Under: Korean Air, Travel

I’m flying from Seoul Incheon to Kathmandu today. I had mapped out the flight when I first booked this, and noted that it covered a distance of 2,469 miles.

When flying a route for the first time, I typically compare it to a route I take more frequently in terms of length. I thought to myself that the flight was just a few miles shorter than New York to Los Angeles. Since this was a westbound flight, I figured the flight would be maybe 5hr30min in the air. U.S. carriers typically schedule New York to Los Angeles flights at around 6hr30min gate-to-gate, and that includes generous padding, plus plenty of time for dealing with two congested airports.


Ford asked me how long the flight was, so I said “maybe five and a half hours, or so.” I knew what time we were scheduled to depart and arrive, though with timezone differences hadn’t investigated the actual flight time.

When I pulled up the flight on Google Flights, it indicated that the flight time was 7hr45min. I assumed this was a glitch, because I’ve never before seen a sub-2,500 mile flight that’s blocked that long.

However, I pulled up the flight on Flightaware, and saw that the flight doesn’t just have that long of a block time, but actually has a flight time that long. A few days ago the flight took 7hr46min in the air, which is longer than the block time.


In looking at the map, it’s clear the flight takes a really circuitous routing:

KE695 2

For example, a few days ago the flight covered a distance of 3,176 miles, while the direct distance is 2,467 miles.

I understand why airlines avoid certain airspaces. For examples, a few months ago I flew Ukraine Airlines from Baku to Kiev, and the flight time was 3hr30min, even though we were just covering a direct air distance of 1,150 miles. But Ukraine Airlines also has a lot of airspace they need to avoid.


However, I didn’t think that would be the same flying from Incheon to Kathmandu, unless it’s terrain related?

So anyone have any insight as to why Korean Air’s ~2,500 mile Incheon to Kathmandu flight takes nearly eight hours?!

  1. I don’t know why a Korean airline would not be able to fly over Tibet, but that would be the logical reason

  2. Because of the Himalaya the flight has some performance limitations. In case of one engine failure the plane would not be able to sustain a sufficient altitude.

  3. I don’t think twin engine planes can fly over parts of the Himalayas, so possibly need to route around them to get to the southern side? That doesn’t explain the southern routing out of ICN but i think we can chalk that up to the great chinese airspace controls

  4. They are trying to avoid flying over North Korea and Mt. Everest. Descending from the north of Nepal is quiet difficult due to the mountains and funny wind conditions.

  5. @Lucky – As far as I’m aware it’s because of one of two reasons:
    1. Flying the direct route brings them directly above the Himalayas, which are one of the highest mountain ranges in world. (Which isn’t much of a problem though.)
    2. Flying direct means flying over the Tibetan region to, which is sparsely populated, thus the number of airports they have the option to divert to in the case of an emergency is too less. Taking this route is however more convenient, god forbid but if an emergency does take place they have a far greater chance of landing at an airport.

  6. I’d say it has to do with congested air corridors in mainland China, corridors are incredibly strict here to a tee and at capacity. They would be routing it in the least congested corridor for sure hence the crazy flight time. Another cool flight that does this is the QF SYD-PVG, watch how it directs to HKG and then follows the coastline up to Shanghai (China’s eastern corridor) also same with the KA/CX SHA & PVG- HKG services.

  7. Only about 20% of Chinese air space is open to commercial flights and the PLA still controls it and will close it for any reason. You’re likely having to fly along specific corridors that don’t necessarily match up with the most direct route.Thats what it looks like per the previous flight’s path. If there’s any bad weather in the area, that could exacerbate it.

  8. It’s because of the Himalayas. I encountered the same situation recently when flying between Delhi and Beijing.

  9. It’s very likely terrain in the higher elevations, as others have mentioned, and I also will say that it’s Chinese air traffic control. I could be wrong on Chinese ATC but over the years Chinese ATC has been notorious for causing delays in the big hubs, as well as the military controlling the airspace lest sensitive sites be seen from the air. I know when I flew from ORD-PVG on a UA flight a few years back the routing was over the polar route, then into Mongolia, and directly over Beijing, Tianjin, and then descending into Shanghai. A third variable might be weather?

  10. As a Chinese and a fan in aviation. I think all of you guys got the point. Just want to add a little more details. First, the direct route is right over the Everest, but that’s not a problem for cruising aircraft but as KTM airport is too near to the Everest on the north side and lack of alternative airport on the way, the aircraft should detour to avoid that since I suppose those aircraft are not high-elevation certified in case of emergency and most airport in that area are Car 4C no more than 4D. There is also another issue with Chinese airway system. From point A to point B, Foreign airlines and domestic airlines most likely go different route. There are certain airways only domestic airlines can go and foreign airlines can only go through designated route between those route.

  11. It’s the Chinese air corridors and this even occurs on domestic routes occasionally. Sometimes you would have two airplanes taking off maybe 10 mins apart flying between the exact same city pairs but the one that took off late would actually finish maybe 5-10 mins early. The reason for this to happen from time to time is cuz expat pilots. If one of your crew is non Chinese citizen, your route is typically more limited while a full Chinese crew is authorized to take short cut here and there… So if you have an American/British captain on an Air China domestic flight, your route would be more limited than a China Southern flight with two Chinese pilots… Usually it doesn’t make too much of a difference since the air force controls 80% of the air space any ways… In case of foreign airlines, you are just stuck with the stupid routing 100% of the time…

  12. Flights to Nepal come from a southern approach as the north has some of the highest mountains in the world – I know this as I am a Nepali and have flown many times to KTM. Coupled with the short distance between the mountains and the airport, I would imagine the descent would be pretty rapid if they did fly in from the north.

    Also Korean flies B777-200 on this route which I think is still the largest plane that lands at Kathmandu.

    Look forward to the trip report and your thoughts about Nepal.

  13. It appears to be terrain related, remember that Everest is not too far north of Katmandu, in addition I would bet that the Chinese government does not like aircraft flying that low over Tibet

  14. Hey Ben,

    Great Travels! Need a little help from you. Should i opt to fly back to singapore from LAX or SFO on SQ Biz, I have both ticket on hold and thinking which would give me the best experience. Which is better in terms of flight, Airport and Lounge experience. Many Thanks.

  15. Terrain. Even flights that don’t originate or terminate in Kathmandu can’t fly over the Himalayas. The peaks are higher than 25000 feet, so if a flight cruising at 35000 feet has an issue like an engine failure or loss of pressure, it wouldn’t be able to descend to a safe altitude.

  16. 1. Terrain, especially in Everest and other mountains in Himalaya
    2. ETOPS issue, no airport near Himalaya who sufficient to handle B 777-200, remind if landing in airport with high altitude need more power, so it’s dangerous to land in that circumstances.
    3. Chinese air corridors limitation, most of the corridors are controled by PLA, so it’s limited option in China air space
    4. Weather and wind issue, it would be a problem and too risky to fly in Himalaya

  17. @Lucky It impresses me how often you’re able to come up with a novel and interesting subject for a post. Often these things seem trivial on the surface, but I for one really enjoy reading them.

  18. No one has mentioned that there is strong head/tail wind in this region along the Himalayas. The same goes to non-stop DEL-NRT flight in winters: only 6.5hrs outbound but takes 10hrs inbound.

  19. By the way terrain is not much of an issue. Many fly over northern end of Pakistan above the Karakoram mountains which easily exceeds 7,000 meters above sea level. The direct flight between Kathmandu and Lhasa just passes through Mt. Everest before crossing the Himalayas. It’s simply Chinese Government does not allow foreign planes to fly over Tibetan airspace.

  20. It might be due to Chinese restrictions on civilian / commercial aircraft but it is more likely terrain related. All flights to/from Delhi across the Himalayas to Beijing, Shanghai, Tokyo, etc do the same (even those operated by Chinese carriers).

  21. China is pissed off at Korea for letting the US deploy long-range missiles there, so, they are restricting air travel as a passive aggressive gesture; Hopefully temporarily.

  22. My bad – The terrain does seem to be a big reason since as MB mentioned many Chinese carriers do avoid flying over Tibet for DEL/KTM – China flights. The only exception seems Kathmandu-Lhasa flight on Air China.

  23. @Lucky, be careful with FlightAware these days – since they refreshed their site a few weeks ago, that “total flight time” number is not accurate, as it’s actually showing the gate to gate time.

    In the case of the flight you reference above, go back to Flight Aware and you’ll see the actual takeoff time was 2:05pm, not 1:51pm, and landing was 6:16, not 6:22. So in this case, yes, still a long flight at 7:26, but not 7:46 like it shows.

    Where this gets skewed is when you push back and have a long ground delay…I have no idea why Flight Aware changed this, they used to be the most accurate out there in terms of showing you your actual air time.

  24. What others have said plus one more thing I haven’t mentioned – haze due to dust/pollution in Kathmandu valley. That can put aircraft in holding patterns for a while. As in hours. On our very short flight back from Lukla to Kathmandu we spent 40 minutes circling around waiting for our turn to land. And that was during the “good” visibility times.

  25. Planes can’t fly over the Himalayas because if a problem occurs they can’t descend below 15000 feet. So if there’s a problem with air pressure it puts passengers and crew in serious risk since the air masks only have 20 min of air

  26. Actually I have also noticed this on the ICN-DEL route on Asiana. I think is a combination of factors, but most likely the main one is head/tail wind. So ICN-DEL flight is blocked at 9hr 10mins, while the DEL-ICN flight is blocked at 6hr 30mins. I have never seen such a big difference between flights between the same pair of cities in opposite directions.

    Actually just checked and it is the same for ICN-KTM on KE. Westbound flt is 7hr:45mins as you have found, but KTM-ICN is only 5hr:45mins.

    This pretty much explains it has to be the wind.

  27. I can’t comment about this particular flight, but I recently flew Asiana ICN-JFK and the normal flight path would be over Russia. Flew directly east over Japan before heading north over the pacific, avoiding Russian airspace.

  28. As others have said, it’s a combination of closed airspace and the headwinds coming off the Himalayas . . . the time doesn’t surprise me at all. I’m only surprised you didn’t think about it — or at the very least, think to check the flight time at the time of booking.

  29. I may be wrong but I had thought it was bottled oxygen supplies in the event of depressurization. The aircraft only has so much and has to head to a lower altitude. It can’t do that in that region within the time frame of the oxygen that is carried without flying the strange route.

  30. Nobody has mentioned overfly charge rates. They vary by country and it can pay to avoid overflying a country en route whose fees are egregious

  31. Great example of the comments being even more interesting than the article. I guess that’s called a “community” ?

  32. Hey rookie million dollar man, I’ve flown everywhere.

    It’s called the 200 knot Jet stream screaming across China.


  33. A few factors comes into play in this issue.

    1. Terrain, potential diversion airport and aircraft capability. KTM is very close to Mt. Everest which lies right on the Chinese-Nepali border. Aircraft has no problem flying over it for sure, but keep in mind that there are only a few airport in the Tibetan Plateau area and the only few being able to handle wide-body jet is LXA (Lhasa, China) and XNN (Xining, China). Also, the terrain around these airports is very tricky. Air China has designated pilots and modified aircraft with specific navigation system for only these high-altitude airports in their CTU base, and I’m sure other Chinese carriers does the same management for these routes and avoid flying there aircraft over Tibetan plateau as much as possible. E.g. URC-CTU flight does not fly over Tibetan Plateau either. Korean Air does not even operate flights to any high-altitude airport so their pilot would be very inexperienced in this kind of altitude condition if a diversion is ever needed. Also, in case of emergency, aircrafts cannot decent to a lower enough altitude to escape the risk of hypoxia, as the average altitude in this area is higher than 3500 m. Last but not least, yes, Air China flies LXA-KTM with their high-altitude certified Airbus A319 with a modified engine, enabling it not to reduce as much performance as other airplanes in high-altitude airports.

    2. Weather. Located not too far from the south slope of Himalayas, KTM does have some tricky wind conditions due to the monsoon and the sudden raise of terrain. Frequent precipitation could be expected at the south slope of Himalayas and makes the approach to KTM from the north way more difficult.

    3. Head wind.
    West wind are especially strong above lower-mid-latitude area. An example would be HKG-IST, which looks way shorter than HKG-CDG, but takes only more than one hours or so less.

    4. Airspace restrictions. China imposes several designated air corridor for foreign carriers in their airspace. Look at flightradar24 and u will see where the aircrafts mostly segregates along. Airspace over Tibetan Plateau are only open to domestic carriers and the military-controlled airspace takes even more share there.

  34. To all the people who think it is because of the chinese airspace, the flight still flies above the chinese airspace so I vote for himalayas

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