A method for inputting ETCS data into a rail vehicle inputs the ETCS data by using an apparatus which is separate from the rail vehicle. The apparatus can, for example, be constructed to be mobile and the ETCS data can be input flexibly at different locations and be transmitted to the rail vehicle, for example, by SMS. The advantage of this approach is that delays resulting from the inputting of ETCS data can be reduced and thus the rail vehicle reaches a “Start of Mission” state more quickly. An apparatus for inputting ETCS data into a rail vehicle and a rail vehicle with an ETCS device are also provided.