In aviation, “retard” is a command to reduce the throttle position. It is used throughout the industry but is especially noteworthy in Airbus aircraft. These highly-automated planes make aural callouts based on the aircraft’s radar altitude, including one telling the pilot to retard the thrust levers on their final approach to landing.

When first heard from the jump seat or in a simulator, the Airbus call out of “50…40…30…20…RETARD, RETARD” can sound a bit odd. Numerous jokes have popped up. After all, who would want to fly a plane that insults its pilot?

The Merriam-Webster Dictionary defines the verb retard as “to delay or impede the development or progress of…to slow up, especially by preventing or hindering advance or accomplishment. For example, chemicals are used to retard the spread of fire.”

In the example of an aircraft, the thrust levers are moved aft to retard the power produced by the engines.