A method for operating a rail vehicle in a railway system includes providing at least one optical waveguide which is laid next to at least one railway track and into which light pulses are fed, using the optical waveguide as a distributed acoustic sensor, and detecting backscattered light. In order to configure such a method in such a way that it meets stringent safety requirements relatively easily, a rail vehicle is used having a sound generator which can be adjusted in terms of its frequency spectrum in such a way that it indicates an emergency. When the sound generator is activated, an emergency signal of the rail vehicle is acquired if a frequency spectrum which corresponds to the adjusted emergency frequency spectrum of the sound generator is detected in the backscattered light. A railway system is also provided.