The following are known Action Replay Codes for Deadly Skies on SEGA Dreamcast (Dreamcast). These codes were also known as GameShark Codes and in most cases will work on both devices.

Device Compatibility: Action Replay & GameShark

Have infinite armour
AE435BD2
00001099

Have infinite missiles
D798899C
0000003C

Have lots of cash
81D3819F
0000C9FF
BA4E3612
0000389A

Have lots of cash
81D3819F
0000C9FF
BA4E3612
0000389A

Have infinite armour
AE435BD2
00001099

Have infinite missiles
D798899C
0000003C