The sound you describe, like a ratchet strap being repeatedly tightened, is commonly known as "thrust reverser noise" or "reverse thrust noise." It is a characteristic sound that occurs during the landing phase of an aircraft equipped with thrust reversers.
Thrust reversers are mechanisms on jet engines that redirect the flow of exhaust gases to help slow down an aircraft after touchdown. They work by creating a reverse thrust, which counteracts the forward motion of the aircraft and assists in deceleration on the runway.
When the pilot activates the thrust reversers, typically after the main wheels of the aircraft touch the ground, the exhaust gases are diverted forward instead of backward. The redirected airflow interacts with the engine and surrounding structures, leading to turbulence and creating the distinct noise you hear.
The noise can vary depending on several factors, such as the specific design of the thrust reversers, the aircraft type, and the engine configuration. It often has a unique and identifiable sound that can be quite loud and distinctive, resembling the sound you described.
It's worth noting that while the sound of thrust reversers is a normal part of the landing process, pilots and airlines make efforts to minimize the impact on noise levels in residential areas around airports through various operational procedures and noise abatement practices.