A marker for the wingtip or other extremity of an aircraft. The marker includes a fabric pouch having a flap containing hook and loop fasteners, to hold the pouch on the aircraft extremity. A fabric tube extends outwardly and substantially horizontally from the pouch and supports a marker flag at its tip. The fabric tube contains a breakable support rod, so that if the aircraft wingtip collides with an object, the support rod will break and the flag will droop, providing a visible indication that a collision has occurred. The broken rod can then be replaced.