Free-fall

An uncontrollable descent or decline as in expressions like, “the economy is in free-fall” is thought to derive from the language of early parachuting in the early 20th century, used to describe the brief, uncontrollable time before the parachute opens. Merriam-Webster disputes this and maintains its first literal meaning originated in America and dates from the mid-19th century long before parachuting. Its current figurative meaning and usage dates from the mid-20th century.