There are countless sensations and noises involved in the operation of an aircraft before, during, and after a flight. Modern airplanes are highly complex machines with an array of moving parts that make noise and have attendant sensations.
The noises and sensations experienced in flight will be expounded upon a logical order from the start to the finish, with the endgame of helping a new or nervous flier get a greater understanding of the processes of flight and what to expect.
At the gate, the airplane may shake, whirr, and whine. The shaking and banging sounds often come from cargo being loaded in the cargo bin located below the cabin and in the aft (rear) fuselage (towards the tail).
Located in the tail of most aircraft is a small jet engine called an APU (auxiliary power unit). The APU provides electrical power and air conditioning on the ground. Being a jet engine, the APU makes a characteristic jet engine noise that one may hear from the cabin.
Before taxi begins, the APU air conditioning air is diverted and employed to spin the engines during engine start. When this happens, the air coming out of the vents may momentarily cease, but should return after the engines start.
Here is a video of the Boeing 747 APU start-up
On the taxi to the departure runway, the APU is able to provide the source of air for the air conditioning or the air can be transferred to the engines. When this happens, there is a momentary change in the intensity of air coming out of the air vents in the cabin (called gaspers). The momentary result is less air coming out of the gaspers and less air noise, followed by greater air quantity and noise.
When the airplane is minutes from takeoff, the flaps and slats will be extended. These devices are located on the front and back of the wings and help in lift production for takeoff. Different airplanes will have different noises associated with their use.
Here is a video of a stationary Boeing 737 extending its flaps
There are four key sources of noise and sensations from takeoff. These include the engines, flaps, landing gear, and aerodynamic noise. The engines create strong accelerations, similar to pushing the pedal to the floor in an automobile. This is completely necessary, as the engines need to propel a lumbering aircraft that may weigh over a million pounds to speeds of approximately 170 miles/hour (274 Km/hour) in a short distance. The noises that are heard from the engines are the result of the shearing of air masses. Simply, the high-speed air coming out of the engines is smashing into stationary air outside and it causes noise.
The landing gear has similar noise emanating from them as the flaps since they are both hydraulic powered. Sometimes, the landing gear will have a loud thud associated with extension or retraction. There is one key difference between the flaps and the landing gear; after takeoff, the wheels of the airplane will be stopped as they are retracted. As a result, there could be some strange groaning noises from the brakes as the wheels are stopped before they retract into the wheel wells.
Here is a video of a Boeing 777 landing gear extension test
This is what takeoff looks and sounds like from the cockpit
The only real change in sensation from the climb is from the transition through 10,000 feet. At this level, the airplane will normally speed up significantly. This increase will increase the aerodynamic noises in the cabin. In addition, it is possible that the airplane engine noise will increase as the pilots increase thrust for the climb. The signature sign that passengers can use to know when the 10,000-foot transition occurs is the chime. The chime is used to signal to the Flight Attendants that the airplane is above 10,000 feet, which is the minimum altitude where they can begin servicing the passengers in the cabin.
Click here to hear some variations of the chime.
Aerodynamic noise is simply the noise from air molecules striking the airplane body (also called a fuselage). The faster the airplane goes, the more aerodynamic noise will be heard in the cabin. The airplane will accelerate to a maximum of 250 Knots (which is equal to 287 miles/hour or 463 Km/hour) after takeoff. Below 10,000 feet, the Federal Aviation Administration requires speeds of 250 Knots or less.
Leveling off is when the airplane stops climbing and maintains a steady altitude. During takeoff, and also landing, the plane will often perform maneuvers known as “step climbs” and “step descents”. This process is given by air traffic control to avoid other aircraft in the area and can be seen in the following diagram.
During level-off and when the aircraft reaches cruising altitude, the engine noise is significantly reduced. This can be alarming because it can get so quiet that it sounds as if the engines ceased operation. Don’t stress, this is most likely just a reduction in thrust due to a combination of thinner air (providing less resistance) and less power needed to maintain the cruising altitude.
Aircraft have such a high level of excess thrust that if the engines were left at their climb setting, the airplane would accelerate to well beyond the speed of sound. Flying beyond the speed of sound is decidedly not a good thing on contemporary passenger-carrying aircraft. Additionally, if the airplane is accelerated further the aerodynamic noises will increase.
Descent is much of the reverse process of the climb. Engine noise reduces, so that the airplane will not accelerate as it “slides” downhill toward the destination airport. When the airplane approaches 10,000 feet, the airplane also has to decelerate to meet the 250-knot requirement discussed earlier.
Since modern jet aircraft are built for minimum drag and are not amenable to slowing down, devices called “flight spoilers” may be employed to help it slow. These devices (sometimes referred to as “the boards” by pilots) are symmetrically situated on the tops of both wings and help spoil the lift and increase drag, thus slowing the airplane down. The most important aspect to remember about the flight spoilers is that they will induce an audible rumble and vibration in the cabin. Flight spoilers and ground spoilers will also be used on landing to help slow the airplane but do not have much of a sensation associated with their deployment.
Flight spoiler deployment on an Airbus A320
As with takeoff, the airplane will need the flaps for better wing lifting ability at low airspeeds. Jet aircraft wings are designed for high-speed flight. Flaps are needed to keep the speed at which the airplane can land at to a minimum. Without flaps, landing speeds would need to be increased significantly and the resulting needed runway length could double or triple! This reduces safety margins and would require more robust and heavy tires and brakes, decreasing the amount of revenue-paying passengers the airplane could carry and increasing airplane costs.
Flaps and landing gear will be extended for landing approximately 2-5 minutes from landing with the same noises and sensations described above. When the landing gear is extended, there are about 1-2 minutes before touchdown. The way the landing gear sensations differ from flap actuation is that occupants will note the change in sensation coming from the underbelly of the airplane.
Once the wheels have touched down on the runway the pilot will reverse the engine thrust to help slow the aircraft quickly on the runway. During this process, the engines will sound like they are speeding up and you will feel yourself being forced forward in your seat due to the rapid deceleration.
The best bastion in the fight against passenger anxiety is getting a better understanding of the process of flight. As hopefully demonstrated, a high degree of technical knowledge is unnecessary to understand noises and sensations of flight but knowing what to expect during flight will go a long way to pacifying your anxiety.
If one fact was gleaned from the preceding reading, it should be this: during takeoff and landing, the airplane’s systems will be operated to a greater degree and, as such, there will be an increase in noises and bodily sensations during these periods.
Possibly the best gauge if you are feeling uneasy is to take a look at the Flight Attendants. If a look of fear exists in their collective eyes, it may be good reason to begin to hold some apprehensions. It is much more likely that the Flight Attendants will appear as calm as a vacationer relaxing on the beach in the Seychelles.
Gosh! This is so helpful and put into practice during my last flight. I can honestly said my fear of flying has lessened ever since I read this. THANK YOU so much!
I was once traveling home from Florida back to Connecticut with my parents back in 2007 and as we were flying over Long Island the cabin got REAL quiet - I mean it did NOT seem normal and I looked at people and my parents and some other passengers started to look around also. I have never been in a plane that got that eerily quiet before - and it sounded like the engines quit. Anyway - we weren't THAT far from our destination airport in Hartford, CT but the plane kept on and we landed safely a little while later. I am not sure what that was all about - could it have been they had to reduce engine power flying over Long Island? Or did something happen and we would have never known? I still think about it to this day and wish I could ask a Pilot if he thinks something could have been wrong or just a reduction of power. Even seemed like we were just gliding. I never panicked but it just didn't seem normal. I also don't remember if I heard engines sound again as we approached the airport but I think so, yes.
What is the sound that occurs when almost everyone has disembarked from the plane, the APU shuts down and the turbines fully shut down. There is some weird repetitive whining sound as if each time the rotor completes one rotation, it whines and it slows down. Like a progressive arc in the time difference between each whine. I am only scared of this plane sound, I seriously think the rotor is just going to like explode.
Cargo compartment doors being opened.
I heard a rumbling that was very low right after take off and I’ve been on this plane every year for half my life btw I’m 11 and I started crying since it was just me and my two sisters and the attendant said she did not know what it was but it didn’t shake the airplane and my sisters heard it too. It was loud and low and continued for about 2 minutes after takeoff.
those are called flaps, they are used for generating lift during take off.
Why did I never hear the sound before even though I have been on this type of plane at least six times? This was a lot louder than anything before.
Hi, depending on you seat the sound of the engines may differ. For example if your seat is located somewhere behind the engines, you will hear a heavy and strong wind sound, but unlike that, if you seat somewhere infront of the engines, once the engines are spooled up, you'll definitely hear a roaring sound caused by a plently of air mass being cut by the front fan which will be continued for a few minutes after take off and will be ceased after because of thrust reduction and engine sound reduction. So there is no reason for cry my man except being exited of being able to enjoy an engine roar 🙂
Thank you thank you thank you for this article and thank you Margaret!
Found this article helpful especially with ‘fear of engine cut out’ when cruising after take off...every time I fly I’m more anxious and now have an understanding hopefully will be better...
Can you do a Part 2? Couldn't see any explanation for screeching sounds as we were speeding down the runway for take-off. I did mention this to a member of cabin crew and he said "hydraulics".... sounded like it needed oil! Was pleased you dealt with the "sound of the engines apparently stopping" mid flight, this occurred on my last flight coming into Heathrow, it almost felt as if we were on a glider! Almost no engine sound whatsoever..
This would totally come in handy for my grandmother who always complains about the sound of the plane. I remember the first time I rode with her when I was little, it's always her usual complaining about why can't they make engines a little less noisy. HAHA. I'll have to share this with her so she'll be better informed. That said, I totally love her! She's just a bit of a fussy person when it comes to the noise of planes.
Thanks for this article; too bad i hadnt read it years ago. I've been on several flights where ive loudly exclaimed, "the engines have just cut out!" (I'm great fun to fly with.) Now i realize, it's just the "level-off" phase. In fairness, it can seem eerily quiet then...like you're in a free-fall to your death. Just sayin'.
Haha I totally hear you on that. The lack of noise was always my nemesis.
another sound you might hear which is scary to those not aware is the crashing of ICe particles along the length of the aircraft during take off and flight from the air conditioning units. This scared the B-HeeSUS out of me last time I flew but was told it is perfectly normal.
Very helpful! EspecialLy explanation of the chime.
Should be printed and put in each seat!
Whenever I fly, I cannot get my mind off this ball fire that I sit on, close by with 100's of gallons of jet fuel, and see that ocean below me.... with a depth of 10 or 11 miles... I cannot reconcile myself with that. I wish they built the airplane with a safety mechanism in case of a fire or whatever it may be,... we can exit to safety. Sometimes I heard the engines speed up it seem there is a mechanical fiction,.. and all of the sudden it stops.... as you point out in your conclusion, the flight attendants are so calmed and collected it seem like everything is cool... I am also worried some of the mechanics might be mad with their bosses and refuse or forget to tide all nuts and bolts in the engines and tires... or refuse to put enough fuel for the flight that could cause a disaster...
I hope this helps. Aircraft maintenance is so detailed and serious that it is pretty much impossible for a single disgruntled technician to Botch a repair out of spite. My husband was AN avionics technician in the USAF. Any work he did on a jet was checked and double checked by another technician(s). Then the work gets inspected by someone higher up before it is signed off. Ultimately there is someone who is completely responsible for everything touched on that aircraft, as well as, everyone who touched it... and everyone else who signed off on the technicians' work AT any point. My HUSBAND jokes that you can't even sneeze or hiccup in An aircraft hanger without it BEING extensively Documented, and More importantly, made known to every responsible link in the CHAIN of command
After all of that, the pilots do their pre-Flight check of every single system. If something comes up questionable, everything stops and no one even thinks about thinking of a pushback.
The words "push" and "back" are out of everyone's vocabulary until the problem is double checked, documented, fixed, documented, checked, documented, double checked, signed off... then checked and double checked again by the pilots, documented, and deemed good to go.
There is so much paperwork, Documentation, and accountability measures in place for commercial Aircraft maintenance that it would be easy to find out who messed up what/when/where/how/why... and if it was intentional or due to negligence. Both of which carry their own set of penalties and consequences.
A disgruntled worker tampering with a plane out of spite will do nothing except for get said WORKER fired, fined, and/or imprisoned. Every aircraft maintenance technician knows They have nothing TO gain from spiteful tampering. Whatever botched part of the plane is going to get fully fixed before it is in the air again.
It WOULD be way more effective For a disgruntled worker to put laxatives in their Bosses' coffee if they wanted to GET a message across... Or just quit their job. Neither one of THOSE options jeopardize hundreds of innocent lives Or CARRIes a prison sentence. For a spiteful tampering to actually be successful, Every person in the HANGER plus THE pilots and flight attendants WOULD all have to be in on it. Go ahead and add the gate attendants plus the ground crew too. Everyone who works with/around aircraft to any extent has a moral obligation to speak up IF they see anything wrong with a plane. If someone loading luggage onto a Delta plane notices something sketchy about A United plane, they have to speak up. If a gate ATTENDANT for a Southwest flight sees something odd about a Spirit plane, they have to speak up.
Oh anything written in all caps is not supposed to look like that. Text input on the comment Box was all caps. Anything that got Auto corrected or filled in by predictive text assumed that I wanted all caps lol. I apologize for any unintentional internet yelling.
A competent accounting for airplane sounds might also ease. One key sound missing from this list is a more angry mechanical pump sound sometimes heard, mostly during ascent. Constant with the engine. Never ends only fades with high airspeed outside.
Not the high pitch whine of a normal jet but sounds more like a fuel pump running hard. It's rather loud and is not always heard on flights. Has an ugly grinding angry mechanical sound. The variance is not invoking confidence in the engineering and maintenance. Cabin crew seemed unfazed but I don't recall the sound in the same plane the other way. What is it?