Doesn't work. The stall is about the angle at which the airflow meets the wing. The gyroscope (with or without glass of water) will tell you the attitude of the

Doesn't work. The stall is about the angle at which the airflow meets the wing. The gyroscope (with or without glass of water) will tell you the attitude of the plane, but nothing about the direction from which the air meets the wing. You can stall in a nose down attitude if you're descending fast, the air comes from "below" and you try to pull out ift the dive thereby increasing the angle at which the air meets the wing. All the while your nose is still pointing below the horizon.