The airship passwords are derived from hints left by the Al Bhed on various ruins throughout the world. You will need to have a significant portion of the Al Bhed Primers to read these hints. The locations of the hints are listed below. Note that all passwords are case-sensitive. For airship secrets, see also list of coordinates.
Start in Calm Lands at the big spire in the north-central part (near a person standing at the edge). Examine the base of this spire to read:
With the vale at your back go forty-nine, then seven to the right in the truest line.
Make sure to WALK (not run) south 49 steps, then 7 steps to the right. This is easiest to do if you are using the D-pad. The next clues are, as follows:
With me at your back go twenty, then twenty to the right.
Right sixteen and right four.
Continue on. Find me.
At this point, you should head north, back to a spot near the spire you started at. Look for a white spot on the ground near the edge to read the password:
The password is... GODHAND
Use this password to acquire Rikku's Godhand weapon.
The first clue is on the blue stone at Besaid Island (located under the structure that has two of the hidden locations on it). It reads:
Kilika and Bikanel join as one.
This is in reference to the blue stones at Kilika and Bikanel, which when combined, give you the password. The stone at Kilika Island (near the south entrance to the forest) reads:
t e p s w r s
V C O I U
The stone at Bikanel Island (at the ruins in the central desert) reads:
h a s o d i
I T R O S
Combined, these give the password VICTORIOUS.
The blue stone in Baaj Temple (towards the right of the first screen) reads:
In the land where bolts of light
illuminate the blackest night
With Macalania behind
the fourth pillar you sight
look not on the left
but on the right.
This corresponds to the tower in North Thunder Plains which is near a save sphere. Written on the LEFT side of the tower (on the right-hand side if you were travelling south!) is:
The password is... MURASAME
Use this password to acquire Auron's Murasame.