fly blind

1. To fly an airplane in extremely low visibility, relying on the plane's instruments instead. The huge plume of ash sent into the air by the volcano forced the pilots to fly blind. A: "Any theories on why the plane crashed?" B: "Well, there's a pretty thick cloud cover. The pilot could have been flying blind." It's pretty incredible that such an inexperienced pilot was able to fly blind and still land safely.

2. By extension, to do something based on guesswork, intuition, or without any help or instructions. Since this is our first attempt at developing an app, we'll be flying blind as we figure out how to get things working correctly. I've never filed my own taxes before, so I'm sort of flying blind. Hey, you're an experienced teacher—think you could help me with my lesson plan? I'm flying blind here.

fly blind

Feel one's way, proceed by guesswork, as in There are no directions for assembling this furniture, so I'm flying blind. This hyperbolic expression dates from World War II, when it was used by pilots who could not see the horizon and therefore had to rely on instruments. It was transferred to broader use soon afterward.

flying blind

Proceeding by guesswork, groping one’s way. The term originated during World War I and alluded to poor visibility. Later it was extended to other enterprises, as in, “My predecessor quit without leaving any instructions, so for this first department meeting I’m flying blind.” See also by the seat of one's pants.