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If you open www.flightradar24.com or their app, then this is what the scene commonly looks like:

enter image description here

As you can see, the South-Central China area is strangely empty and the aircraft look to take a circular route around it instead (like this Emirates A380 to Incheon):

enter image description here

So, my question is why don't aircraft fly over that area? Also, I occasionally see some China Air Force aircraft going to that area..

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    $\begingroup$ Why are they flying where there are more emergency airports and less inhospitable mountains? $\endgroup$ – mins Aug 19 '16 at 7:01
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    $\begingroup$ Related: Flexible Use of Airspace in China - ICAO // and // Air force can help combat crowded skies $\endgroup$ – mins Aug 19 '16 at 7:28
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    $\begingroup$ Also related: China Air Traffic Congestion Worsened by Military Control. China has large amounts of restricted airspace and many routes aren't available for civilian use, especially by foreign carriers. They're making some efforts to improve the situation, but in short: you fly where the government says you can fly. $\endgroup$ – Zach Lipton Aug 19 '16 at 7:36
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    $\begingroup$ That said, Flightradar24 may be distorting the situation somewhat. They may have pretty limited coverage over, say, the Tibet region. Flightradar24 says "In areas where Flightradar24 normally have coverage, all major airports are marked with blue airport markers." Note the lack of any blue markers anywhere in this region. There are flights in the area that you just aren't seeing. $\endgroup$ – Zach Lipton Aug 19 '16 at 7:46
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    $\begingroup$ @ZachLipton: Very relevant comment, also 8 km mountains create more shadow than usual on existing stations. $\endgroup$ – mins Aug 19 '16 at 8:05
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While Him's answer is correct, part of the reason that there aren't many airways over central China is just that there's rarely a reason to fly there. Where possible, aircraft prefer to take paths along great arcs, which are the shortest distance between two points on the surface of a sphere (such as Earth.)

In short, there simply aren't many common air routes between city pairs where the shortest path passes over central China. If you look at the first image posted in the question, you will see that the flights into China are primarily flying either to or from Europe or Eastern North America (the ones crossing over Mongolia,) Japan or Western North America (the ones crossing over the Sea of Japan and East China Sea,) India (the ones flying over South China,) the Middle East (the ones flying over North China,) or Australia/Philippines/Thailand/Indonesia/Oceania/etc. (the ones coming in from the South.)

For your great arc path to pass over Central China, you'd need to be going to or from central China itself (which isn't terribly populated,) Siberia (which is even less populated,) the Central Indian Ocean (which is open ocean with Antarctica on the other side,) or the mountainous region between China and India (which also doesn't have a lot of air traffic.) So, there's normally just not much reason to fly there and, thus, not much reason for China to have airways there.

For the specific example that was shown in the question of the Emirates flight, the arc on which its flight path is shown across Northern China is, in fact, very close to the great arc between Dubai and Incheon, which looks like this:

Great Circle Path from Dubai to Incheon
Great Circle Path from DXB-ICN Source: gcmap.com

This map should give you something of an idea for how unpopulated Western China is:

China on Google Maps China, as seen on Google Maps Source: Google Maps

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    $\begingroup$ This population density map is telling too. $\endgroup$ – Zach Lipton Aug 20 '16 at 6:07
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    $\begingroup$ A very good answer. I‘d suggest to add the point that it’s rather difficult for many commercial aircraft, especially twins, to comply with regulatory requirements regarding terrain clearance following engine failure or oxygen supply for the minimum altitudes and diversion distances/times at altitudes dictated by the Himalayas. $\endgroup$ – Cpt Reynolds Feb 11 '19 at 21:42
  • $\begingroup$ This answer, like the others, seems question-begging: "Why don't aircraft fly over Tibet? Because there isn't much air traffic." I think a good answer should explain why the two most populous countries in the world have so little air traffic over their border. $\endgroup$ – Hugh Sep 10 '19 at 16:21
  • $\begingroup$ @Hugh This answer does explain exactly that. Nearly all of the population of China lives in the Eastern part of it. Thus, routes between populous Chinese cities and populous Indian cities fly well to the South of Tibet (because the shortest path between those cities is South of Tibet.) Tibet itself is very sparsely populated. $\endgroup$ – reirab Sep 10 '19 at 16:58
  • $\begingroup$ Where does the great circle between Delhi and Beijing lie? $\endgroup$ – Hugh Sep 10 '19 at 17:12
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Because there is only 1 airway (B345) in Tibet.

enter image description here
Source: Chinese AIP - 15 Jan 2019

China (PRC) creates 2 sets of Aeronautical Charts, AIP and NAIP. AIP is aeronautical charts only listing airways for International flight. It is open for public and foreign organisations. NAIP is a confidential and more accurate aeronautical charts listing airways for both International and Domestic flight. Its standard is different from AIP.

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    $\begingroup$ NAIP is [...] confidential -- honest question, why would it be confidential if it's distributed domestically and to international (and presumably commercial) flights anyway? (unless I'm misunderstanding your wording) $\endgroup$ – Jules Aug 29 '16 at 14:08
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    $\begingroup$ @Jules My understanding of what he said was that NAIP lists both domestic and international use airways (i.e. all of the airways,) not that its distribution is both domestic and international. The AIP, which is distributed to international organizations, lists only the international airways. $\endgroup$ – reirab Aug 29 '16 at 15:58
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    $\begingroup$ Sadly, the server on which that image resided appears to have gone offline. :( Any chance you can find another version of it somewhere (and perhaps let SE upload it to its imgur so it stays around?) $\endgroup$ – reirab May 2 '19 at 15:20
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According to FlightRadar24, I see Flight TV9886 of Tibet Airlines flying into Lhasa right now.

Flight TV9886 from FlightRadar24

So, the answer seems to be that they do when they need to.

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  • $\begingroup$ Note that the dashed line is predicted path (no surveillance coverage), so it's not necessarily proof. Although if it's going to Tibet, surely it'll fly over Tibet :) $\endgroup$ – ymb1 Sep 10 '19 at 13:40

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