[citation needed] Flicker vertigo in a helicopter occurs when the pilot or front passenger looks up through the blades of the main rotor as it turns in the sun causing the light to strobe.
In extremely rare cases, severe reactions can happen including: This situation can occur whenever flickering light conditions exist.
Examples of this include: [4] According to The US Naval Flight Surgeons Manual, flicker vertigo is a rare occurrence.
[5] Flicker vertigo has been considered as a principle for various forms of non-lethal weapons.
[6][7] A related crowd-control device was invented by Charles Bovill, which "employed a combination of ultra-sonic waves and strobe lights to induce acute discomfort, sickness, disorientation and sometimes epilepsy.