Jacques Ibert (1890-1962) wrote his Flute Concerto, dedicated to Marcel Moyse, in 1932.
In its third movement, Allegro Scherzando, Ibert wrote a series of challenging tremolos. Here are some fingerings for flutes with and without a C#-trill key.
Try both the regular and alternative fingerings and choose those that best suit you.
5 measures after rehearsal #43

5 measures after rehearsal #49

5 measures after rehearsal #63

Download a PDF of the Above Article