Before revision: Kopp–Etchells effect produced by a CH-47 Chinook helicopter in Afghanistan The Kopp–Etchells effect is a sparkling ring or disk that is sometimes produced by rotary-wing aircraft when operating in sandy conditions, particularly near the ground at night.
After revision: TheKopp–Etchells effect produced by a CH-47 Chinook helicopter in Afghanistan The Kopp–Etchells effect is a sparkling ring or disk that is sometimes produced by rotary-wing aircraft when operating in sandy conditions, particularly near the ground at night.