From SMS Power!

Cheats: After Burner (アフターバーナー)

Continue

To have access to two continues until Stage 7, press ++ during the Game Over screen. To have access to unlimited continues until Stage 17 using the same command above, press x100 during the opening screen before starting the game.

Safe flying

Bank your aircraft as far to the left as possible. Hold the D-pad in this position and you cannot be hit until the 12th stage.

Easy refueling

Line up with the refueling plane when it appears. Use the D-pad to move across the top of the plane, then press ++ to refuel.

Action Replay codes

00C01807

Infinite lives (keeps showing 7)

00C017XX

Stage select (turn it off before the end of the stage. Replace the XX on the code for a hexadecimal number from 00 to 11 [for those not familiar with, it'd be something like 00, 01, (...), 09, then 0A, 0B, (...), 0F and finally 10, 11]. Note that this code will change the actual number of the stage [i.e. it will start on "Stage 0" and the last one will be "Stage 17"])

00DE03XX

Trigger music and sound effects (Replace XX with 81-93. You must enable and disable the code for it to work. The sounds will replace those already programmed to activate.)

See the main page for After Burner (アフターバーナー)