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Frequent and a maybe-a-little-too-nervous flyer here. Recently I've been taking the ORD-WAW course with LOT on the 787 Dreamliner and started noticing a sound that's been a little spooky for a person who's seen a little too many flight-crash explanation videos (I know, I'm trying to quit). My next flight is in October, and before that I wanted to find any technical reason why I shouldn't worry.

The noise was captured on this youtube video. It's the "thudding" noise that cuts right before the video ends: LINK

This sound took place after landing but I believe I experienced it also before take off and it's accompanied but a rhythmic beating feeling from the bottom.

If there's anyone here who could elaborate on the supposed source of the noise it would be very helpful for me.

Additionally, if you guys could also elaborate on the high-pitched noise it would be even better because it's a sound I keep hearing before take-off and right before landing and it's scaring me every since the flight prior where after some technical-issues were fixed the high-pitch noise would be followed by this weird sound close to a high-pitched version of trying to start an engine, followed by a hissing-sound (which made me thing we're about to crash only...four dang times).

I understand this question might be a little vague, and if there's any details then I would love to elaborate. Being and engineer I suppose I'm much more forgiving for strange noises when I somewhat aware what it could be.

Any help would be greatly appreciated!

aln447
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    Hopefully you don't get to the airport by car... – sophit Sep 13 '23 at 13:31
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    Learning what the different sounds are is good, but not the only way to manage nervousness about flying. Eventually you will hear other sounds that you can't identify and then the cycle repeats. You need to continually remind yourself how safe flying is. In the past ten years a total of five people have been killed in U.S. airline accidents out of 80 million airline flights. You might say I know that but I still feel nervous. It's like feeling hunger, it creates a primal nervousness, you have to keep reminding yourself that you are not in physical danger. Not saying it's always easy to do. – Steve Pemberton Sep 13 '23 at 13:42
  • @StevePemberton Thanks for the feedback. Trying to dig into realizing what's making me so nervous though I found that what I fear is simply the sheer amount of moving parts a plane has that if one goes wrong everything falls apart. I know that there are people checking the planes but being an engineer in a different field myself I know how well people often check things... – aln447 Sep 13 '23 at 14:16
  • @sophit I understand the statistics but then again if my engine fails, or the steering wheel stops working I can just stop the car and get out. In a plane its usually "nothing's wrong, till something is reaaaaly wrong" – aln447 Sep 13 '23 at 14:17
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    Understand but still, travelling by car is some 60 times deadlier than flying! And the reason is simply that something going wrong in a car is much more probable than in an airplane: If your tire explodes while on the highway, you die; if your airplane loses a wing while flying, well it doesn't lose a wing in the first place – sophit Sep 13 '23 at 15:02
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    @aln447 - I am sure you have had a debate with someone who states facts out of context and refuses to acknowledge facts that don't fit the point they are trying to prove. Without realizing it you are doing this to yourself. Part of your brain is saying "airplanes fly at deadly altitudes, my life depends on many things going right. Cars are on the ground, if I have a problem I can stop the car and get out". That part of your brain is refusing to acknowledge that 40,000 people per year die on U.S. highways. How well did the "I can just stop the car and get out" strategy work for them? – Steve Pemberton Sep 13 '23 at 15:24
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    @aln447 - "I know that there are people checking the planes but being an engineer in a different field myself I know how well people often check things". Again this is focusing on only one facet. Statistics show that while imperfect they do an excellent job. Now consider driving, your life depends on the unknown random driver, in who knows what mental condition, who is guiding their 2-ton mass of steel within a few feet of your 2-ton mass of steel, at a combined speed of over 100 mph. Your life is in their hands. If you survive great, but now here comes the next car, and another, and another. – Steve Pemberton Sep 13 '23 at 15:38
  • @StevePemberton I mean, you're 100% right, I fully understand that planes are much safer than cars. The problem I'm facing is the approach to the "one thing goes bad I'm dead" part of the equation, which does't happen in cars. With cars I feel safer hearing ie. a strange rumble because I know how to handle it. In turn in planes I know that the turbulences are ok and there's much handling in the plane for the turbulences so consequently I feel safer going through turbulence than through hearing strange sounds. I guess what would help is knowing how well planes are prepared for mech problems – aln447 Sep 13 '23 at 16:48
  • I know it's dragging the topic out to almost psychoanalytical terms, and I apologize. I'm just trying perhaps finally acquire the logical mindset that "that weird sound is 99.9999% not going to make me meet Elvis" – aln447 Sep 13 '23 at 16:50
  • Is Elvis dead??? Maybe something like this might help you – sophit Sep 13 '23 at 17:20
  • "The problem I'm facing is the approach to the "one thing goes bad I'm dead" part of the equation, which does't happen in cars." A) there are VERY few part of an aircraft where if "one thing goes bad you're dead", and B) there are plenty of parts of a car that will do the same (like a wheel coming off at 75MPH - oh, wait, that happened to me and didn't kill me either). Every commercial aircraft you'll ever fly in has at least 2 of every critical system, sometimes 3 or even 4, and they serve as backups to each other. – FreeMan Sep 13 '23 at 17:48
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    @aln447 - you are being selective in what you count as risk and this is giving you a false view of the risk of flying compared to driving. You seem to be looking for a way to continue to be selective but still reduce feelings of nervousness. This can be dangerous if it leads to being selective in the other direction about other activities, including driving, where we don't necessarily have to be paranoid, but which is where we really should be putting our attention. Like avoiding ever looking away from the road for more than a second (73 feet at 50 mph) or talking on the phone even handsfree. – Steve Pemberton Sep 13 '23 at 18:53
  • @FreeMan That is a good point. I wasn't aware of the backup system. That's reassuring. I guess all of those examples I saw were before these systems were established. Then again we still make new mistakes, as was the case with 737-MAX where MCAS did not have a backup checking sensor even though the functionality was critical. – aln447 Sep 15 '23 at 13:45
  • @aln447 backup hydraulic systems and computers have been common on commercial aircraft more or less since they were invented. The original 747-100 had backup hydraulic systems, as did the L-1011 and DC-10. (Quick examples from the 1960s off the top of my head - I'm sure they're far from the oldest with backup systems.) – FreeMan Sep 20 '23 at 21:52

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Without watching the video, I can almost guarantee you the sounds you're hearing and movement you're feeling is flaps/slats moving (get a seat over wing and you'll see them moving) and if airborne then its undercarriage doors opening/closing and the gear locking into place. I assure you these sort of sounds are not out of the ordinary and almost certainly nothing to worry about.

Another sound you might hear/feel whilst still parked is the cargo bay doors closing and locking into place, again get the right seat and you'll hear it just after the last baggage cart moves away.

Jamiec
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  • Thanks for the reply! What since the feeling was during taxi (although away from the gate) and after directly after landing then I believe it was the cargo doors.

    What would you say about the high-pitched noise though? It's honestly the one I'm worried about more due to the "car-starting" sounds it made on my August flight.

     – aln447 Sep 13 '23 at 14:20
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    @aln447There are so many actuators, and hydraulic/electronic systems on these jets that its hard bordering on impossible to know what every sound is. – Jamiec Sep 13 '23 at 15:11
  • @aln447: On Airbus you'll hear the sound of dogs barking in the cargo bays, it's for safety. – mins Sep 13 '23 at 16:31
  • @Jamiec That's what I thought. Still hoped that since the high-pitched sound acompanies every start and landing procedures then maybe there would be some explanation to it. I'm slowly thinking if it's not the slats since the sound is usually long and happens at times when the plane would-probably-need-them. Still...if this sound produced the car-starting noises then means during the start and landing there was something wrong with them so...yikes? – aln447 Sep 13 '23 at 16:52
  • @mins Yep. Heard of this. Unfortunately the sound is nothing like that. – aln447 Sep 13 '23 at 16:53
  • Ok, the high pitch sound is 99% the flaps. I did some digging around this and found a video of someone experiencing the exact same car-start-up noises as I did: https://youtu.be/R-XepgQKqhs?si=LZBPVJiylYUMj7DF&t=52

    In this case I'm a little calmer knowing it's the flaps. Still wonder why suddenly they'd start to make that additional noise

     – aln447 Sep 13 '23 at 17:15
  • Even better evident here: https://youtu.be/lbR80J8zmLg?si=kxK6gX38_YCx0Fxc&t=144

    It's quite clearly the flaps since the moment the weird sound comes up, they start moving down. In this case it makes me wonder even more why I hadn't noticed it before since I've been flying 787 since 2011...

     – aln447 Sep 13 '23 at 17:17
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    "far from the gate", @aln447, would absolutely NOT be cargo doors! Well, if it is, there should be alarms going off in the cockpit for an open door and they'll taxi to some stopping point where ground crew will come, pick up anything that fell out and stuff it back in the trunk, er, cargo hold, then latch & lock the door and triple check that it's closed correctly. Also, none of these sounds are specific to the 787 - they all make noises at varying volumes and you'll hear them on every flight if you're listening closely. – FreeMan Sep 13 '23 at 17:55
  • Marking the answer as the solution since it brought me the closes to the solution. Thank you all for the help! – aln447 Sep 15 '23 at 13:46