Can't tell you which Convention or whatever it was that the UK signed up to but yes, European Regulations, once they go through the European Parliament and get published, are the law in the UK and take precedence over any national legislation. Note that this is the case foe European Regulations - EU Directives are different. An EU Directive has to be implemented in each member States' legislation.
You say the context is unimportant but I would hazard a guess that it's in relation to the Single European Sky regulations.