What happens to a visual altimeter when it is in the jumper's burble?

When a visual altimeter is within the jumper's burble, it reads unreliably. The burble is an area of turbulent airflow created by the jumper's own body and equipment. This turbulence can cause erratic pressure changes around the altimeter, leading to unreliable readings.

Visual altimeters function by measuring atmospheric pressure to determine altitude; when the air is not flowing smoothly (as in a burble), the pressure readings can fluctuate unpredictably. This means that jumpers should be cautious when interpreting their altimeters during freefall, especially when experiencing significant body movement or changes in orientation, as these factors can adversely affect the accuracy of the instrument's reading.

Understanding how the burble can impact altitude readings is crucial for jumpers to maintain situational awareness and ensure safe parachute deployment.