So here I am, rolling my first Fate character for Thursday. The setting is classic , cinematic pirates (arrr!) and I figure my priate character should have a phobia of sickness and sick people.

Anyway, on the question, where does that fit in the Fate system? In classic Fudge it wouldbe a Fault. In Fate I am not so sure.

It started off thinking of it as an Aspect, but I can't imagine it coming up that often. That is to say, realistically you could have sick people left right and centre, conditions on a ship being what they were, but that would be rather dreary and I don't think it's the tone the GM is aiming for.

Nor do I don't see it as Skill or Extra. I guess the other option is just to write it on the character sheet with no attached mechanic together with hair colour and other minor details.

Thoughts?

You're right that it doesn't make much sense for this to be an Extra or Skill - the only place to put it is as an Aspect.
You might think putting something that might be rare as an Aspect is a waste, but in FATE, aspects are statements to the GM: "I want this to be important in the game."
So if you have a phobia or some feelings about sick people, the GM should be creating (or allowing you to create) situations where those things do come into play.
This doesn't mean sick people have to be there in every session for it to be relevant - capturing ships with cargos of medical supplies, meeting doctors, and the like are just simple off-the-top-of-my-head ideas which would provide opportunities for the aspect could come into play without needing actual sick people to be present.
But even better would be if another player took an aspect or skill that would also work to bring such things into play - like, maybe they actually are a doctor (or sick person! - a syphilitic pirate :)), or have one as a follower or relative. Or maybe you could do that yourself.

What Darren said.  It breaks down like so:

A fear or phobia is definitively an aspect.  Exposing you to the source of that fear is a compel, getting you fate points.

Aspects are important to your story.  If you're not really that interested in seeing sick people come up as a regular or even semi-regular plot point, then this is where the question really arises.  Not, "is a phobia an aspect?", but, "is my phobia important and interesting enough to me to be a part of my sheet and thus a part of the larger story of the campaign?".  Which brings us to the next point.

Aspects should be a message to your GM of what makes an interesting story for you and your character. If your phobia isn't actually interesting to you -- or is something you aren't interested seeing come up with any regularity -- then it's really, in the end, just an insignificant personality quirk.  In such a case, keep it in mind, and play to it the one or two times it ever comes up, and save your aspect slots for the stuff that actually matters to you for your character's story.

Thanks guys,

Yeah that makes a lot of sense. I guess I can either relegate the phobia to a footnote on the character sheet as a quirk, or maybe change the Aspect to something like 'Superstitious', not quite the same but its got the same element of irrationality and it's a bit more flexible and fun.

As an aside, I am totally impressed by the Fate ruleset.  It's so elegant, I am very much looking forward to playing it.