What is the Apollo 11 guidance computer bug?

It's a sequencing error in P63 routine where a register might hold stale attitude data during DSKY interrupts, causing brief 0.3-0.8 degree errors — never triggered on mission.

Could the Apollo 11 bug have crashed the lunar landing?

Unlikely, due to timing and the 1202 alarm's lucky reset, but in worse scenarios, it could've compounded drift leading to abort or impact.

Why study Apollo Guidance Computer code today?

GitHub's open repo lets us learn verification from 1960s genius, applying to modern rockets, drones, and AI safety.

📦 Open Source Projects

Apollo 11's Dormant Bug: The Guidance Computer Glitch That Never Woke Up

Imagine a tiny logic flaw lurking in the Apollo 11 guidance computer, poised to scramble descent calculations. It slept through the moon landing — but what if it hadn't?

theAIcatchup Apr 07, 2026 5 min read

Highlighted bug in Apollo 11 guidance computer assembly code on GitHub

⚡ Key Takeaways

Undocumented sequencing bug in Apollo 11's P63 routine could cause transient attitude errors under rare DSKY timing. 𝕏
Never activated thanks to mission timeline and 1202 alarm side-effect — bugs saving bugs. 𝕏
Timeless lesson: even heroic verification misses edges; vital for today's autonomous systems and AI. 𝕏

Published by

theAIcatchup

Community-driven. Code-first.

#AGC assembly #AGC bug #guidance computer bug #space software

Worth sharing?

Get the best Open Source stories of the week in your inbox — no noise, no spam.

Originally reported by Dev.to

⚡ Key Takeaways

The 60-Second TL;DR

theAIcatchup

Share this article

Worth sharing?

Related Stories

React 19.2: Pre-Rendering the Web's Next Move Before You Click

React Labs Finally Lifts the Lid on Years of Secret Dead Ends

React 18 Upgrade: Turbocharge Your App Without the Crash

Euro-Office: Europe's Open-Source Rebellion Against Microsoft's Office Empire

Stay in the loop