There is apparently a small range of HP printers which Apple's software supports from the Ipad.
It's a crap situation really but that is what you get if you choose to become a fully contributing member of the Church of Jobs
The next best thing is to print to a PDF (for which I gather there are 3rd party add-ons) and email that to somebody who has a normal printer.
Same issues with the Iphone, apparently. We have one here and I did get some 3rd party add-on printing over wifi (Altamail I think it was; I replaced the crappy built in email client with it) but the quality was very poor. And it worked only if the said printer (which could be any of many types) was attached to a PC running the Altamail print server program. This is done in corporate application areas but if you are a travelling pilot then obviously the printer which you have available won't have this server available.