Preferably a seat mounting rail for a passenger aircraft includes a base connected to a crown by a web. The crown includes two support flanges protruding laterally in opposite directions from a reinforcement zone that connects to the web and that has a seat-securing groove extending longitudinally therealong. Floor panel elements can be supported on the support flanges. The reinforcement zone top surface preferably does not protrude above the support flange top surfaces but rather is at least substantially flush and planar therewith. The single horizontal base flange forming the base, the single vertical web and the support flanges preferably form a generally I-shaped sectional profile. The reinforcement zone may include a triangular sectional hollow lower reinforcement structure tapering to the top of the web. Large-area floor panels can span continuously laterally over the rail and can be arranged independently of the spacing between the rails.