Aus einem anderen Forum
I may annoy some people here with the amount of detail I’m going to post, but I’ll do it anyway because (1) it’s been posted elsewhere in more scattered form and (2) I’m not actually revealing the 3Xs or other secrets that make the tricks work. Nothing I post here will help a person book a FD unless they go out and find it themselves. The dog went too far by actually telling people what 3X to use. I am merely showing them how to find it. If this helps a few newbies figure out how to trick, too, and contribute what they find, I think it will be a good thing going forward. All I ask is that you please remember to code your posts. You will only hurt yourselves and others if you make it too easy for others to duplicate your itineraries without putting in the effort.
The mods can always pull this before MP exits beta. I will not mention the great search engine I use in deference to Aktchi, who’s posts I appreciated reading on FT, but I’m sure most of you already know what it is.
Basics
You can only dump certain airlines, and only for international trips.
The fares that can be dumped are often specific to certain city pairs (A-B-A for the RT, and X-Y for the 3X). They are often direction specific (e.g., you cannot do B-A-B with X-Y or A-B-A with Y-X).
Sometimes multiple 3Xs will work on the same RT, and sometimes multiple RTs will work with the same 3X.
The amount removed by the 3X will vary for different RTs.
Sometimes tricks will work for several cities on the same continents. For example, you can say C1-C2 to refer to flights from North America to Europe. Convention dictates that C1 is North America, and you name the other continents left-to-right, top-to-bottom.
Step 1
Find a RT with low base fare and high fuel surcharge (usually termed YQ). Use a month-long search to find a low total fare, and then double check the fare construction to confirm that it has these two features. You cannot do anything to lower the base fare or taxes, so they should be minimal. Flying out of LHR, for example, is a bad idea because of the high departure tax.
Step 2
Find a 3X with a low base fare and taxes. It is usually going to be a short, one-way, international trip on another alliance. There are exceptions (may not be short, may not be international, may be the same alliance, etc.) but the further you deviate the less likely you will find one.
It might be good to try areas with lots of airports near each other at the same time by doing a 300-mile search. You can search for a flight from X,Y,Z to X,Y,Z for example, and it will return X-Y, Y-X, and all the other permutations. This is also a good way to find which direction actually works as a 3X when you get to Step 3.
Step 3
Try combining your 3X with your RT in a multi-city search. You will need to pick specific dates, so hopefully you remember which ones work. It would also be best to specify the airline or alliance for your RT to avoid a time-out while the search engine works. (It only runs for 1 min, so if it doesn't find your flights in that time, it may not perform the FD.) Don’t bother specifying the airline for the 3X as often the fares for different airlines are very similar and you don’t know which one is actually going to work.
Step 4
If you are having trouble, you can be creative. For example, you may find that you can dump IAH-LHR-IAH, but you live in SEA. You could try a positioning flight to get to and from IAH, or you could try an open jaw (OJ) such as IAH-LHR-SEA so you only need to position yourself one-way. You can do the same thing in reverse, IAH-LHR/CDG-IAH to avoid the departure taxes at LHR. You can also try a 1X if it works right for you. But a 1X must be flown before you begin your RT, and unlike a 3X, if you skip your 1X, your whole itinerary will be cancelled. Finally, you do not have to dump a RT. Some people will try to dump C1-C2-C4, and then book a separate ticket home from C4-C1.
Step 5
Book your fare. The particular search engine we all like doesn’t allow you to book tickets, so you need to find someone, not the airline, who will actually book the ticket. This usually involves searching multiple travel web sites to see which one actually lets you buy the ticket. When you find one, you should post that, but it should also be coded. And remember, don't call anyone to reserve seats or try to change a flight. It will kill the deal.