Photo: Shutterstock Have you noticed a particular sound that starts as a loud, steady roar right after takeoff and gradually softens as the aircraft climbs?
The Colombian Civil Aviation Authority aims to explain this mystery in the air that "can generate doubts or fears".
The peculiar sound is commonly associated with thrust reduction after takeoff, when pilots reduce engine power from takeoff thrust to a lower climb setting. The aircraft continues climbing, and the sound inside the cabin may become noticeably quieter.
To get into more detail, takeoff requires high engine thrust to accelerate the aircraft and lift it off the runway. Once the aircraft has climbed away from the ground and the pilots follow the aircraft manufacturer's procedures, thrust can be reduced to an appropriate climb setting. The exact timing and power setting depend on the aircraft type, operating procedures and flight conditions.
Passengers may notice the change as the aircraft transitions from the initial climb to the next phase of its ascent. Other sounds and sensations can also change during the flight:
- A high-pitched whine: Some aircraft produce a whistling or whining sound from engines, turbines or airflow. Its pitch can change with engine power and flight conditions.
- A rushing or hissing sound: Air flowing around the fuselage and wings creates a continuous rushing noise, which can become more noticeable when the engine sound decreases.
- A loud rumble or clunk during descent: As the aircraft prepares to land, the landing gear extends. Passengers may hear a mechanical rumble, followed by a noticeable clunk when the gear locks into position.
- A change in noise when flaps extend: The wings' flaps and other high-lift devices move into position to help the aircraft fly at lower speeds during approach and landing. Their movement may produce a whirring or mechanical sound, while airflow noise can also change.
- A brief whoosh or thump during landing: The wheels make contact with the runway, creating a thud and a sudden increase in rumbling. On many jet aircraft, spoilers rise on the wings to reduce lift, and reverse thrust may add a loud roar as the aircraft slows down.
- A squeal when the aircraft touches down: The tires can briefly squeal as they spin up to runway speed on contact. This is a normal sound during many landings.
- A low hum or vibration during cruising: Even when the flight feels quiet, passengers may hear a steady hum from the engines, airflow and onboard systems.