This is a very strange thing. An African airline opened a flight between Tokyo and Seoul? Usually, based on my experience, an airline has a hub, and it has outbound and inbound flights from and to the hub. For example, Cathay Pacific has flights from and to its hub in Hong Kong. However, the flights between Tokyo and Seoul neither goes to or from its hub.

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    Is it possible that they fly from Tokyo to Ethiopia via Seoul, and sell some tickets for the Tokyo/Seoul leg? Commented Jun 15 at 20:06
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    So indeed, Ethiopian flying ADD-ICN-NRT and back, and benefiting from whatever freedom of the air allows them to sell flights on that leg.
    – jcaron
    Commented Jun 15 at 20:45
  • It is a long time since I last flew to the US, but I recall that United Airlines and Air New Zealand both operated flights LAX-AKL-MEL, and that it was possible to buy seats on the AKL-MEL leg (to replace the passengers who got off in AKL). Commented Jun 16 at 22:23

3 Answers 3


These types of flights are called "Tag" flights.

The flight you're looking at has the flight number ET673. If you look that flight number up, you'll see that the flight actually goes from Tokyo (NRT) to Seoul (ICN), and then on to Addis Ababa (ADD) in Ethiopia.

Think of this flight as being a little bit like a long-distance bus running between two cities - whilst it's running between cities A and B, it might still stop at other cities along the way to pick up and/or drop-off passengers - meaning that a single bus can serve multiple different city pairs. In this case the airline is doing the same thing - by stopping in ICN on the way between NRT and ADD, they are able to transport passengers from both NRT and ICN to ADD.

Normally this style of flights will be used when the airline doesn't have sufficient demand to justify running separate flights to both Tokyo and Seoul, but by merging these two into a single flight they can make it viable. Occasionally (although rarely nowadays) they may also be run when the total flight distance is too long for the type of aircraft being used so a fuel stop is required - at which point the airline might as well treat it as an extra passenger stop as well.

Depending on the laws of the countries involved, airlines running flights like these may or may not be able to actually transport passengers only on the 'tag' section of these flights (eg, NRT-ICN). In this case it appears that you can purchase flights between those two cities (without continuing on to/coming from Addis Ababa), which will have required both Japan and South Korean governments approval.

In other situations the airline may not be allowed to sell tickets only on the 'tag' flight. eg, I once flew from Cape Town in South Africa to Istanbul, Turkey. The flight stopped in Johannesburg between those two cities, and whilst new passengers were allowed board, none were allowed to get off, as Turkish Airlines didn't have permission to carry passengers between Cape Town and Johannesburg.

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    Another common scenario are "triangular" flights, where instead of doing A-B-C and then C-B-A on the way back, it's a single flight A-B-C-A. This is most often done when the airline doesn't have fifth freedom rights for the B-C flight (so it doesn't matter if they fly it only one-way), and when B and C are roughly the same distance from A. Here NRT is quite a bit further than ICN, and ICN is actually nearly exactly on the great circle route between the two, and they have fifth freedom flights, so there are quite a few reason to just make a stop both ways.
    – jcaron
    Commented Jun 16 at 11:41
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    Turkish Airlines also has a triangular flight to Vietnam: IST-HAN-SGN and it seems no one can board the the HAN-SGN leg
    – phuclv
    Commented Jun 16 at 13:02
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    @phuclv Turkish have a few triangular flights, including BOG-PTY and MEX-CUN. BA and AF have a number of them in Africa. I haven’t checked if they are able to sell the foreign segment alone.
    – jcaron
    Commented Jun 16 at 19:57

Flights like this are called fifth freedom flights, and they're reasonably common. Basically, if Ethiopian can fill half a plane with passengers to Seoul, and half a plane with passengers to Tokyo, it makes commercial sense to combine the routes and fly Addis-Seoul-Tokyo.

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    And often (usually?) you can't actually buy a ticket if going just from B to C (in this case Seoul to Tokyo).
    – JonathanReez
    Commented Jun 15 at 21:16
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    In many cases that's true because foreign airlines are often forbidden from taking paying passengers internally or within a region. In this case I would suspect that Tokyo and Seoul are far enough apart that nobody imposes this restriction. If it's not forbidden then the airline is going to sell the ticket. Commented Jun 15 at 23:43
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    @JonathanReez By definition, "fifth freedom" flights are where you can buy tickets on them. Without 5th freedom rights they might be able to run the flight, but not sell tickets for the 'tag' leg of the flight only. In this case, you can buy tickets, so it is a 5th freedom leg.
    – Doc
    Commented Jun 16 at 3:24
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    To be clear, freedoms of the air are not automatic, each country can grant those freedoms individually to other countries (usually in exchange for the same thing the other way around).
    – jcaron
    Commented Jun 16 at 9:21
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    @phuclv This is not some unique one-off snowflake, there are plenty of fifth freedom flights operating in Asia, esp from hubs like Singapore and Hong Kong. Commented Jun 16 at 21:46

While the two existing answers have already correctly covered the specific flight in question, I want to point out that fifth freedom (or tag) flights are not the only explanation for seeing an airline operating a flight outside of its home country.

For instance, United Airlines is planning to base a small fleet of Boeing 737s at Tokyo Narita Airport (NRT) to operate intra-Asia flights. These are obviously not tag flights as the aircraft don't ever leave the Asian continent, and while some of the passengers onboard might be connecting to/from United widebody flights to the US, United also has local traffic rights in Tokyo and thus will be able to transport local non-connecting passengers as well.

A flight like this would be considered a "seventh freedom" flight.

  • That's interesting, I once saw a small United plane (no range for Hawaii or Alaska) in Osaka and I assumed it was going to Guam. Could it also go to other places in Asia?
    – André
    Commented Jun 17 at 13:52
  • @André Yep, that appears to be the plan. These aircraft used to be based in Guam but once they're stationed in Tokyo they'll fly routes like Japan-Philippines which are completely outside of any US territory.
    – Mophotla
    Commented Jun 18 at 22:06

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