Definition
A type of jet engine thrust reverser that uses a movable physical barrier, such as a clamshell or target-style door, deployed into the exhaust stream behind the engine to block the rearward flow of exhaust gases and redirect them forward, producing reverse thrust to help slow the aircraft after landing.
Plain English
A set of doors or panels that swing into place behind a jet engine after landing, physically blocking the hot exhaust and bouncing it forward so the engine helps slow the aircraft down.
Context Anchor
Seen in jet aircraft systems, landing rollout procedures, and maintenance discussions about thrust reversers.
Derivation
Mechanical because the blocking is done by physical hardware (doors, buckets, clamshells) rather than by redirecting airflow internally. Blockage describes what the hardware does to the exhaust stream. Thrust reverser names the function: reversing the direction of thrust.
Why Pilots Care
Provides additional deceleration force that shortens landing distance and improves safety margins on contaminated or short runways.
Grounding Statement
Picture the engine’s exhaust normally flowing backward; this system moves doors into that flow and turns much of it forward to oppose the airplane’s motion.
Intuition Check
Do not read “reverser” as meaning the engine spins backward. Here, it means the exhaust flow is redirected so the thrust acts against the aircraft’s forward motion.
Example Sentence 1
The aircraft uses a mechanical blockage thrust reverser, with two clamshell doors that close behind the engine after touchdown to redirect exhaust forward.
Example Sentence 2
During the preflight the first officer verified that the mechanical blockage thrust reverser system was armed and the blocker doors were stowed.