More than 20 million people in the U.S. are afraid of flying. Sitting in a chair that's floating in the air may be technologically stunning to some, but that floating-in-a-tin-can feeling puts some passengers on edge and sends their minds racing: Do the flight attendants look worried? What was that bump? And, oh man, what was that noise?!
But you don’t have to worry. You’re more likely to drown in your own bathtub than you are to perish in an out-of-control flight. In fact, the last time a U.S.-registered airliner had any fatalities was in 2009.
So unless the sound you hear is the flight attendants telling you to assume a bracing position—which really only means there’s the potential for a problem—everything’s most likely O.K. Still, the unknown can be scary, so we asked Captain John Cox, a pilot who’s flown more than 14,000 hours, to help us decode all those strange airline sounds.
Here’s a non-exhaustive breakdown—by sound—of everything you’ll hear on a flight and what each of those noises means.
20 Minutes Before Takeoff: Two dings in a row, the first a higher tone, repeated twice.
This is an intercom call, indicating that one crewmember wishes to speak to another.
15 Minutes Before Takeoff: Single ding.
This is a call from the flight deck (cockpit) to the flight attendants asking them to pick up the phone. (Often this means, please bring us coffee.)
10 Minutes Before Takeoff:
A light pound from under the plane, two whirring noises that sound like a drill.
The staff is closing the cargo hold door.
The sound of heavy wind as the plane begins to taxi to the runway.
The wind noise indicates a change in the air source. Cox said, “Air is used to start the engines and to cool and heat the cabin. Therefore, it must be redirected. Wind noise can indicate that the redirection is taking place.”
Rattling and Creaking.
While taxiing or flying, you may hear a lot of rattling from different components of the plane. This is perfectly normal, Cox said. Interior panels and galley components on planes have a bit of room to move around, because they can be changed out. This causes routine rattles and creaks, like a house settling.
Takeoff: Two quick, loud thumps from under the plane, and a repeated whooshing noise that sounds like a spinning propeller.
The whooshing noise is air from the engines (the air used for the cooling and heating system) changing as the RPM of the engine increases. The air system needs to adjust for the airflow rate and temperature changes as the plane climbs. As for the thumps, that’s the landing gear retracting.
5 Minutes After Takeoff: Two loud beeps of the same tone.
These beeps let the flight crew know the plane has reached 10,000 feet. Below that height, there’s a regulation that the flight deck only be called for safety-related issues—the sound keeps the cabin crew informed.
5 Minutes Before Drink Service: One loud ding.
This is an intercom chime from one flight attendant to another to discuss the upcoming service.
10 Minutes Before Landing:
Two loud dings of the same tone.
As before, these beeps indicate the plane has reached 10,000 feet, this time on the descent.
Rumbling noise that sounds like the engine is revving up.
This is the slats and flaps being extended on the wings.
5 Minutes Before Landing: High-pitched whirring.
This is another slats and flap noise—it’s the sound of the hydraulic motor that controls them.
2 Minutes Before Landing: Hydraulic pump sound and a thunk.
This is the landing gear coming out.
Cox also mentioned a rare event that, when it happens, tends to scare passengers. It’s called a compressor stall, and it happens when there’s degradation in the airflow pattern into one of the engines. The engine backfires as a result, causing a sound like a shotgun blast, and the plane lurches. Normally everything will settle right down after, but occasionally this will happen multiple times in a row before everything stabilizes. It’s unnerving and everyone screams, but Cox says it’s still not a problem—even if that particular engine fails, the plane is capable of flying using only the remaining ones. You’ll be fine.
"Airplanes talk to you," Cox said. "All you have to do is listen. You can tell a whole lot about how the airplane’s being flown. It's like listening to your car."