[nik-]

Perhaps one pilot suicide. The pilot and the co-pilot struggle when the other realizes what's going on. The plane climbs and descends erratically during this struggle. The one who desires the suicide wins the struggle, regains control and starts heading north towards Andaman Islands, but then changes track again to direct the plane off into the Southern Indian Ocean. Either decompressing the cabin, or not, and lets the plane fly til it drops out of the sky.