Hello Charlotte!
On Laurie Riley’s website, there’s a great article about travelling with your harp : Traveling with Your Instrument – Part 1
Definitely check it out.
However, I can tell you horror stories about travelling with your harp by plane. Someone from my french Website got his harp literally axed down in Moscow because of the pins inside, which they took for hidden weapons.
Other people having instruments (including some guy from a famous rock band) get their instruments destroyed every day by airlines that don’t take any responsibility.
– Always have a copy of the Terms and Conditions of the Airline with you, highlighting the parts where they say your harp is allowed, and have another confirmation (= e.j. printing out a customer service mail) with you. That guy at the airport will not have learned the T&C by heart.
– As much as possible, don’t put your harp in the hold. If it’s definitely too big, have put your harp in a bag, wrap that bag in bubble paper, then crate it in solid material.
If you do, always make sure that you have a sticker on the case detailing what you have inside, in English and all the other langages people might speak (even for a stop).
– Always be prepared to pay more… Whether for an extra seat, or overcharge fees…
– Always be prepared that the guy behind the counter on the given day might give you so much trouble for it that you might have to face the choice to leave the harp or not take the plane…
(Sorry for the downer tone!)