In fact, the Kopp-Etchells effect is a new name. It was named after two soldiers who died in Afghanistan in July 2009. The Kopp-Etchells effect is a result of dust striking helicopter blades as they take off or land at night, causing a bright 'halo' effect around the spinning rotor disk. So, if it happens at night, you can watch an amazing show. Take a look at pictures.