NDBs have no fail flags and are, as some commentators above have pointed out, subject to a number of errors (5 in all). Why do so many people continue to support this rather outdated crude technology as preferable to the FAA approved modern alternative? Is it because we have much more rigorous tandards in Europe? I think not. The 'special weather' argument hasn't been used much these days.
As pilots start to build a level of trust in GPS for approaches all over the world it is becoming time for the slow moving regulatory bureaucracies of Europe to embrace this technology otherwise people will just use it outside the training loop - and that is dangerous. What is needed is an international organisational approach that would cover training in aviation for such matters.
Of course the slow move away from ground based approach aid provision presents challenges of control for the authorities that maybe like to maintain the status quo. The traditional approach that maintains jobs and income streams....