Common Flight Sounds Explained
2 min read
The short answer
Every sound on a plane has a normal, known cause. Most come from the engines changing power, the flaps and landing gear moving, or the air system working. Once you know the pattern, the sounds become familiar instead of frightening.
Your Guide to Flight Sounds
Strange sounds feel scarier when you can't see what's making them. Here's what you're hearing, in the order you'll usually hear it.
Before Takeoff
Humming during boarding — the APU, a small engine in the tail that powers the lights and air conditioning before the main engines start.
A loud thunk under the floor — the cargo doors closing.
Engines winding up — each main engine starts in turn, then settles into a steady hum.
Mechanical whirring — the flaps sliding out, to give the wings extra lift at takeoff speed.
A "barking dog" sound — on some Airbus planes during taxi. It's a hydraulic pump sharing pressure between systems. Normal and well known to frequent flyers.
During Takeoff
A rise, a short pause, then a loud roar — the pilots let the engines settle at part power, then set takeoff power. Loud means they're doing their job.
Rhythmic thumping — the front wheels rolling over the lights set into the middle of the runway, and over its joints. It stops as the nose lifts.
Thunks and whirring after liftoff — the landing gear folding away and its doors closing. It's supposed to sound like that.
During Climb
The engines go quieter — the pilots reduce power once the plane is high enough. Completely planned.
More whirring — the flaps going back in, in stages.
Dings — the crew calling each other, or the seatbelt sign changing. They're not alarms.
During Cruise
A steady hum — the engines at cruising power.
Clicks and air sounds — the air conditioning and pressure system adjusting.
Small changes in engine tone — tiny power adjustments to keep the speed just right.
A slow "wow… wow… wow" hum — two engines (or two air-conditioning units) humming at almost the same pitch. The tones mix into a gentle pulse called a "beat", like two guitar strings slightly out of tune. It's common on twin-engine jets, including older A320s, and harmless.
During Descent and Landing
The engines go quiet — less power is needed to descend. They're still running.
A soft rumble — the speed brakes, panels on the wings that help the plane slow down.
Whirring and a thump — the flaps coming out, then the landing gear going down and locking.
A loud roar after touchdown — reverse thrust, helping the plane slow down. Loud but brief.
The Pattern
Mechanical sounds happen at the big moments: takeoff, flaps and gear, and landing. Engine sounds change when the power changes. Every sound has a reason — and once you know it, it becomes familiar instead of frightening.
Sources
- Patrick Smith, Ask the Pilot — the Airbus "barking dog" (PTU) sound: https://askthepilot.com/?p=3047
- FAA, Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25) — aircraft systems, flaps, landing gear and powerplants: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak
- FAA, Airplane Flying Handbook (FAA-H-8083-3) — normal takeoff, approach and landing procedures: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook
- Bombardier, US Patent Application US 2018/0050809 A1, Synchronization of aircraft engines — small speed differences between engines causing audible "beats" in the cabin: https://patents.google.com/patent/US20180050809A1/en
- Newsweek, Pilot explains every "scary" airplane noise (2024) — the pause at part power, and the thumping of the runway's centre-line lights: https://www.newsweek.com/plane-noises-sounds-pilot-explains-viral-1901344
- Airbus, Safety First: Engine thrust management — thrust setting at takeoff — take-off thrust set in two steps: https://safetyfirst.airbus.com/engine-thrust-management-thrust-setting-at-takeoff/