Hacker News Reader

> and you remind yourself of the sailing motto, "If the bearing does not change, a collision will occur".

It's also the anti-aircraft-missile's proportional guidance motto. (Being from a landlocked country, it doesn't surprise me that I learned about it from anti-aircraft missiles first.)

View on HN

It's also an innate (or at least universally acquired) mental heuristic. IIRC, there are experiments showing that if, say, a baseball player can't readily make use of a fixed background by which to gauge and maintain a constant bearing viz-a-viz the object to be caught when positioning themself, their success rate plummets.

Searching for "Outfielder Problem" should bring up some interesting literature.

Isn't this how the early AIM-9s worked?

It's pretty much how most modern missiles work, as far as I can tell, and it's very natural to use it on missiles with passive guidance in particular (as opposed to for example missiles with control guidance, the oldest of which used beam riding). Maybe some super-advanced ones calculate optimal trajectories of some sort but that requires more storage, more computing power, and perhaps even a way of estimating distance, whereas proportional guidance only requires angles.

Reply on news.ycombinator.com