be flying blind

1. To be flying an airplane without the ability to see, relying on the plane's instruments instead. After the volcano sent that huge plume of ash into the air, the pilots were flying blind for nearly an hour. Don't let on that we're flying blind—I don't want to create a panic among the passengers. I don't have enough training yet to be flying blind like this! I need to be able to see and follow the coastline!

2. By extension, to be doing something based on guesswork, intuition, or without any help or instructions. As this is our first attempt at building 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.

be flying blind

If someone is flying blind, they do not have any knowledge to help or guide them in a particular situation. We will be flying blind into a world we don't know anything about. Without this information, the company is flying blind and likely to crash. Note: A pilot is flying blind when they are piloting an aircraft without using visual navigation, but relying solely on their instruments.