Belfast is part of the UK so she doesn't need a passport to enter.
The airline may require photo id in the form of a passport. What airline are you travelling with?
Thanks for your replies. Will check with the airline, but if she does need a passport does it not make a mockery of the ease of EEC borders, when in fact it is the UK?
"Children under the age of 16 travelling on domestic flights in the UK, France, Spain and Portugal are not required to provide identification if accompanied by an adult who can vouch for the child’s identity."
But if she is flying alone, your daughter will need acceptable photo id.
If she is travelling with another carrier, you need to check their particular requirements.
Are you going with her? Check the airline Val, they do differ. Ryanair for example only accept passports as ID (and they don't let anyone fly unaccompanied under 16).
Ryanair should not be allowed to do that. Who do they think they are? Any form of photo id should be acceptable. Has anyone ever challenged them over it?