Best read with Danger Zone playing on loop
Like most people, you’re probably an absolute expert at landing on the aircraft carrier in Top Gun for the NES. But if you’re in the silent minority that have not yet mastered this skill, you’re in luck: I’ve done a little reverse engineerining and figured out precisely how landing works. Hopefully now you can get things really dialed in during your next practice session. Let’s get those windmill high-fives warmed up!
tl;dr: Altitude must be in the range 100-299, speed must be in the range 238-337 (both inclusive), and you must be laterally aimed at the carrier at the end of the sequence.
As a reminder in case you haven’t played Top Gun in the last few decades (weird), the landing portion of the stage looks like this:
Mercifully, the game suggests you aim right in the middle of the acceptable range per the “Alt. 200 / Speed 288” text on your MFD. Altitude and speed are both controlled by throttle input and pitch angle. There’s no on-screen heading indicator, but the game will tell you if you’re outside of the acceptable range (“Right ! Right !”). The ranges for speed and heading are pretty tight, so focus on those: the range for altitude is much wider.
After about a minute of flying the game checks your state and plays a little cutscene showing either a textbook landing or an expensive fireball. Either way, you get a “Mission Accomplished!” and go to the next level (after all, you don’t own that plane, the taxpayers do):
Memory locations of note:
| Address | Contents | Acceptable range (inclusive) |
|---|---|---|
| $40-$41 | Speed stored as a binary coded decimal | 238 - 337 |
| $3D-$3E | Altitude stored as a BCD | 100 - 299 |
| $FD | Heading, ranging from -32 to +32 | 0 - 7 |
| $9E | Landing state check result | 0; other values change the plane’s trajectory during the crash cutscene |
Speed and altitude are stored as binary coded decimals, likely to simplify the rendering of on-screen text. For example, the number 1234 is stored as 4660 (ie., hex 0x1234).
The function at $B6EA performs the state check and writes the result at $9E. If you’re just here to impress your friends and don’t want to put in the practice, the game genie code AEPETA will guarantee a landing that Maverick and Goose (spoiler: may he rest in peace ) would be proud of.
Here’s my annotated disassembly for those following along at home:
landing_skill_check:
06:B6EA: LDA $3E ; Load altitude High cent
06:B6EC: BEQ $B724 ; Branch if High cent == 0 (altitude < 100)
06:B6EE: CMP #$03
06:B6F0: BCS $B720 ; Branch if High cent >= 3 (altitude >= 300)
06:B6F2: LDA $41
06:B6F4: CMP #$04
06:B6F6: BCS $B720 ; Branch if High cent is >= 04 (speed >= 400)
06:B6F8: CMP #$02
06:B6FA: BCC $B724 ; Branch if High cent is < 02 (speed < 200)
06:B6FC: BEQ $B706 ; Branch if High cent == 02 (speed >= 200 && speed <= 299)
speed_300s:
06:B6FE: LDA $40 ; Load speed Low cent
06:B700: CMP #$38
06:B702: BCS $B720 ; Branch if Low cent >= 38 (speed >= 338)
06:B704: BCC $B70C ; Branch if Low cent < 38 (speed < 338)
speed_200s:
06:B706: LDA $40
06:B708: CMP #$38
06:B70A: BCC $B724 ; Branch if speed < 238
speed_ok:
06:B70C: LDA $FD ; Load heading
06:B70E: BMI $B718 ; Branch if heading < 0 (too far left)
06:B710: CMP #$08
06:B712: BCS $B71C ; Branch if heading >= 8 (too far right)
06:B714: LDX #$00 ; speed ok, heading ok; 0 == success
06:B716: BEQ $B726 ; Branch to return
too_far_left:
06:B718: LDX #$02
06:B71A: BNE $B726
too_far_right:
06:B71C: LDX #$04
06:B71E: BNE $B726
too_fast_or_too_high:
06:B720: LDX #$08
06:B722: BNE $B726
too_slow_or_too_low:
06:B724: LDX #$04
return:
06:B726: STX $9E
06:B728: RTS
Now get out there, and snag that third wire.