You're right that if you want to illuminate an entire airline cockpit intense enough to blind the crew, then you'd need a sizeable laser, bigger than the garden variety terrorist would likely bother with. If the goal is to shoot down a specific plane, then a sure kill would be necessary. However, if the goal is to take out a plane out of the pattern, then it wouldn't be necessary.

You would know far more about aviation, but here is my reasoning... If you use a small beam then yes, I agree that eventually you will hit an eye, maybe both eyes of a pilot... this would definitely be a danger to the craft but with a copilot there the plane could be landed safely... I assume the goal is to make a plane crash, not just to hurt someone on the flight deck... additionally the first few partial successes would tip off the authorities that someone was trying to blind planes.... This would bring intense scrutiny and precautions making your job harder. So for you to achieve the goal of crashing a plane, you need something approaching 'one shot one kill'.

My point is that if the goal is to dazzle the crew, a sure kill wouldn't be necessary. Go to a busy airport and you'll see a stream of airliners on final approach to the active runway. If at first you don't succeed, go for the next one (especially if you're using a nonvisible IR laser). The ones that you miss would be none the wiser.

I hope my posts don't make it sound like I spend a lot of time plotting terrorist acts- I don't, but this specific scenario is one that I have thought about some because I get questions about the risk of my laser hitting a plane.... (Essentially ZERO risk)...