The German multi-billionaire Klaus-Michael Kühne is wont to say straight what he means. When Lufthansa or Swiss fly with aircraft from other companies, he sees it as “false labeling” because he prefers “the original”. Many holidaymakers are like Kühne, who is by the way the largest single shareholder in Lufthansa. They pay attention to which line they are booked on. But the surprise at the gate is sometimes great – when the passengers are supposed to board a plane that they weren’t expecting.

Booked Lufthansa – flown with “Air Unknown”: More and more frequently, a completely different airline is on the ticket than on the tarmac. This is by no means an accident, the interplay has method. The airlines even have a technical term for it: they call it “code sharing” when a company markets other aircraft under its own flight number.

This hide and seek game is popular. Lufthansa, for example, now shares jets with industry giants such as United Airlines, the Scandinavian SAS and Thai International, but also with relatively unknown airlines such as the Croatian Adria Airways, Air India and Egyptair.

The competition is no different: those who have booked Air France can meet the Czech CSA or the Romanian Tarom. Instead of the expected British Airways, passengers sometimes board the Chinese China Southern or Royal Jordanian. The Dutch KLM can fly with Air Serbia and Bulgaria Air. And Singapore Airlines customers sometimes find themselves on Egyptair chairs.

Almost every international airline today has partner lines with which it shares machines and routes. The advantage for the airline is clear: it can offer routes and flight times without taking the risk of having its own aircraft. Costs go down, profits go up.

The passenger, on the other hand, is the fool. After all, he booked the airline he trusted, often paying more for it than for a competitor’s ticket, because he expected a certain level of service and aircraft standard. And then suddenly he has to fly with another airline and test their service.

One of the minor annoyances is when the usual black bread is missing for breakfast and there is no local newspaper on board. Often the stewardesses also understand bad German.

Another disadvantage can be the different baggage regulations of the airlines: while one airline allows suitcases weighing 23 kilograms and ten kilograms of hand luggage, another airline allows suitcases to weigh only 20 kilograms and hand luggage to eight kilograms. Before a codeshare flight, you should definitely check the baggage regulations of the participating airlines!

There can also be differences in terms of compensation and compensation payments in the event of cancellation or flight delays on codeshare flights. If Lufthansa gets stuck in the Canadian snowstorm, the passenger is entitled to EU compensation payments. With Air Canada you would have to mess around with the Canadian guidelines.

But that’s not all: annoying transfer connections are often kept secret via codesharing. The Air France flight schedule, for example, pretends a direct flight from Frankfurt to San Francisco. In reality, the flight of the French ends in Paris, from there it continues with the partner company Delta. With 19 hours total travel time, the passenger has plenty of time to realize that flying direct with Delta Air Lines would have been almost four hours faster.

There is no legal basis for code-sharing practices. Because what the passenger perceives as a sham is legally completely legal. The Warsaw Convention of 1929, which regulates international air travel, only obliges the “carrier” to carry the purchaser of a ticket. With which aircraft and with which crew is up to him.

So the only thing left to the customer is to see through the game. Here are a few tips on how to unmask most airy deceptive packages based on the flight plan: Unusual flight numbers make those in the know suspicious. At Lufthansa, for example, high numbers from 5000 often stand for cooperation flights.

A clear sign of codesharing is the so-called double designation. “JPLH” in the timetable means: joint flight by Adria Airways (JP) and Lufthansa (LH), flown by Adria Airways (first abbreviation).

Asterisks do not bode well: They usually stand for machines from other companies. The explanation is often hidden at the bottom of the website: There you can find out that one star stands for the flight with a partner airline, a second means that you have to change at least once.

Flights between third countries are almost always suspect. If Swiss allegedly flies between Buenos Aires and Santiago de Chile or British Airways from Munich to Paris, then something is wrong. Because take-off rights from a foreign country to a foreign country, without touching the home country (so-called seventh freedom of traffic rights), airlines very rarely receive.

When booking long flights, it is always worth asking about the exact route with all intermediate stops, the type of aircraft in question and the companies involved. Many booking websites answer these questions very accurately if you know where to look. With Lufthansa, for example, you only have to look further down the flight number line, and there you will find (in small letters) the information you want, i.e. which airlines are actually operating which flight.