Originally Posted by
Often1
Just to be clear, this is a very common scenario, yet here we are at the end of 2018, and this issue has not yet been tested. Or it has been tested and nobody has taken it to the ECJ or a national precedential court.
The best I've found is
this, an issue of the Official Journal of the European Union which has some comments from the European Commission on Regulation 1371/2007 on train travel. Section 4.2.3 discusses the meaning of "comparable transport conditions" under that regulation. As Regulation 261/2004 on air travel uses an almost identical formulation, "comparable transport conditions" might have the same meaning under both regulations. To my knowledge, it has not been tested in court under either reglation.