talk of code sharing when two or more airlines share a scheduled service. Each
of the airlines involved offers the flight concerned under its own flight
number, but it is operated by only one airlines. So there can be different flight
numbers for a single flight.
One example from the DUS timetable
Delta Air Lines, KLM and Air France offer a nonstop flight to Atlanta (ATL) from
Düsseldorf on a code sharing basis. The KLM flight number for this flight is
KL 6025, the Air France flight number is AF 3614 and the Delta Air Lines flight number is DL 091. The flight, however, is
operated by Delta Air Lines.
ticket shows the flight number of the airline that issued it. On the
information boards in the terminal, in the app and on the websites, all flight
numbers associated with the flight are shown on a rolling basis with the
notation “Code Sharing”.
code sharing method is mainly used within airline alliances like Star Alliance, One World or Skyteam. This allows the
airlines to offer flights that they do not operate themselves, but are operated
by a partner airline of the alliance concerned.