Airship Passwords and Locations
On the Airship when you talk to Cid he will give you a menu with 3 different options; search, list and input. List will display all of the different locations you can fly to and selecting one will fly you there automatically. No flying over the world like in previous Final Fantasy games.
Select Input and you'll be brought to the typical screen in Final Fantasy X with the alphabet. For this part there are 3 different codes that you can put in - all three of them will add a new location under List for you to visit when you input the code correctly. Each of these codes are case sensitive. I have them in all caps for a reason!
Next to each code I have the item that you can find there.
GODHAND - This will lead to a weapon for Rikku, Godhand. You'll only be able to open this treasure chest if you've first acquired the Celestial Mirror.
VICTORIOUS - This will lead to a piece of armor for Rikku.
MURASAME - This will lead you to a weapon for Auron.
Airship Hidden Coordinates
Inputting coordinates on the Airship is a bit different than putting in codes. When you select "Search" from the menu after talking to Cid it will let you search coordinates on the world map. Pressing X on a correct location will unlock it. It's as simple as that. Imagine doing this without a guide... I mean jeeze man... HOURS.
Anyway here's all of the locations that you can find on the world map. Omega Ruins is the super hard dungeon of the game.
Baaj Temple (X14, Y57) - You can obtain Anima here as well as Lulu's ultimate weapon the Onion Knight.
Battle Site (X41, Y57) - You'll find the Phantom Bangle armor piece for Lulu here.
Besaid Falls (X31, Y75) - You can find Dragon Lance here, a weapon for Kimahri.
Mi'ihen Ruins (X35, Y57) - The Sonar weapon for Rikku can be found here.
Omega Ruins (X72, Y35) - This is one of the hardest side quest dungeons within the game.
Sanubia Sands (X15, Y42) - Ascalon Weapon for Tidus with Double AP ability!