Bumps in the Night:
Certain airplane noises can only be heard at night

Bumps in the Night:
Certain airplane noises can only be heard at night

Our nighttime perceptions encompass a complex cornucopia of psychological and sensory ingredients: flow experience (being in the zone), depersonalization (a sense that things around us aren’t real), dissociative experience (lack of continuity between thoughts, surroundings and actions), visual deprivation, mind-wandering, disorientation and fatigue. All of which can result in summoning the Boogeyman. In a training environment, it’s described as MOA – manifestation of apprehension. But after last month’s dissertation on chemical equations, stoichiometric mixtures, CO poisoning and butter pecan ice cream, I think we’re all ready for less of the “clinical” flavor and more of the “ice cream” flavor. Since dawn is coming later, dusk earlier and a ghoulish but candy-coated holiday approaches, we’ll review our nighttime anxieties and piloting perceptions from a less clinical and a sweeter pilot-y vector.  

Don’t overreact when you hear bumps in the night – analyze the situation.

You Willingly Accept Some Risk

The phrase “things that go bump in the night” is used as a humorous way of referring to real and imagined nocturnal disturbances of all sorts. The commonly cited source of its origin is a British prayer that English poet Alfred Noyes includes in his 1909 anthology “The Magic Casement.” To wit: “From ghoulies and ghosties and long-leggety beasties and things that go bump in the night, Good Lord deliver us!” 

If you love flying, you willingly accept some risk from said ghoulies, ghosties, long-leggety beasties and things that go bump in the night. Flying at night offers some benefits, however. The air is generally smoother, less traffic, controllers are not as busy, and convective weather with lightning is easier to spot. The main difference is, well, it’s dark, and the boogeyman lives there. Even though our pilot senses don’t need coaxing from darkness to stay sharp, our diminished ability to see will cause our other senses to heighten. And some of our modern-day tech may exaggerate this effect.

There is anecdotal evidence that ANC (Active Noise Cancelling) headsets increase our awareness of previously unnoticed or new sounds. I’m always amazed when I power up my Bose A20 and note which sounds disappear and which remain. For example, when I wad up papers the sound is crisp and clear but the sound of the instrument gyros is gone. We all know that ANC headsets cancel out certain frequencies common to aircraft interiors by using a trick of physics called “anti-phase.” That is, they listen to cockpit sounds and produce a balancing sine wave. Consistent noises like the low hum of engines, gyros and fans are easier to cancel when compared to sudden, random sounds like a pop, bang or bump.

Bump (as a pilot-y noun)
A protuberance in flight; a light blow, impact or jolting collision. Often used to describe anything unknown that might be frightening to a pilot, especially a noise.

We have all heard the aviation adage about sounds and bumps that can only be heard at night, and we all understand its meaning. Usually, we have no significant follow-on bump but sometimes the noise becomes relevant and will precipitate a reaction, checklist procedure or a decision –particularly if the noise is recurring. Perhaps the bump/noise causes a “skipped heartbeat,” the implementation of a checklist procedure or, if we have simply heard too many bumps in the night this night, an early landing. After all, our heightened awareness at night can be frightening and fatiguing. Here are a couple of stories from readers about such events:

From Ray A.

I departed Owensboro, KY, at 0300 with a planned arrival of 0600 in Charleston, SC. It was a solo flight at FL190 in my Duke. About 45 minutes into the clear, half-moon night, I heard a solid thump that seemed to originate on my right wing. Man, I was startled! The darkness then seemed to close in as the night time psyche kicked in. I crosschecked the instruments to get a sense of how the aircraft was performing. Systems were normal; the aircraft continued to perform perfectly, but I still worried and wondered what happened? What could be wrong? What is going to happen next! I was never so happy to see the sunrise. It was a beautiful sight and all my worries dissipated. I never discovered what caused the bump in the night or if it was just my mind playing tricks on me.

From Peter M.

I was flying from SAV to DPA one moonlit night above a cloud layer at FL200 when I heard a bang followed by a hissing sound. Hearing a bang through the Bose headset made me think that it must be something serious, possibly a pressurization issue. But cabin psid seemed ok and cabin rate of climb was zero. Then I thought maybe I hit a bird and the hissing sound was related to a bird strike. I put on my O2 mask just in case. Then I thought, since I came from Georgia, maybe there’s a snake in the airplane – a very loud snake! I was perplexed and ready to make the mayday call as I kept mentally and visually chasing the sound. But the remainder of the flight was normal. The hissing sound was there on the next flight and the flight after that. I didn’t realize it until I took off my headset and noticed a difference in the sound. Turns out my headset ear cup wasn’t making a good seal and that was causing a hissing sound. It probably had been that way all along and I never gave it a second thought until that night when my nighttime senses let the boogeyman come to scare me. The bang that I heard is still a mystery.

This next event, while not after civil twilight, typifies the confusion and anxiety we may encounter after hearing an unfamiliar noise.

From Michael H.

Crossing the Sierra Nevada mountain range in a C-152, I was climbing through 12,000 feet when there was a loud explosion. Even with a noise-canceling headset, it sounded as if the engine had come apart. Training kicked in and I recited my ABCs aloud: Airspeed, Best place to land and Cockpit. Then I realized that the engine was still running. A further check of the airplane revealed no defects. The rest of the flight was one of heightened senses and paranoia. Several hours later, while unpacking my luggage, I discovered that the bag of Keebler Soft Batch cookies that I had purchased in the Central Valley of California (240’ MSL) had exploded in the grocery bag right behind my head.

Why Do We Hear More Things at Night?

Flying is hypnotic and all pilots are willing victims to the spell.

– Ernest K. Gann

Hyperesthesia is an increase in the sensitivity of any of your senses: sight, sound, touch, and smell. It can affect just one or all of the senses. Often, the heightening of an individual sense is referred to by a separate name. For example, increased sensitivity of touch is called tactile sensitivity, and increased sensitivity of sound is called auditory sensitivity. However, when surrounded by silence, the brain creates noise to fill the silence and we hear this as tinnitus (the perception of noise or ringing in the ears). But tinnitus is not our issue at night because the airplane produces enough white noise to override tinnitus. It’s the noisy, nighttime goblins threatening to increase drag, remove lift, destroy thrust, get us lost, run us out of gas or fill our airplane with smoke that we always think about and hear at night. But why do we hear, or think we hear, more things at night? 

It could be our pilot sense as described by Ernie Gann: “It’s when things are going just right that you’d better be suspicious. There you are, fat as can be. The whole world is yours and you’re the answer to the Wright brothers’ prayers. You say to yourself, nothing can go wrong…all my trespasses are forgiven. Best you not believe it.” 

So perhaps it’s our senses telling us to hear and feel every single thing lest the ground riseth to smite us. Hearing an unexpected noise in the dark is scary. Sometimes the things that go bump in the night are not quickly identified, and thoughts of fatal failure modes enter our mind. Maybe it’s because the night seems still, the radios are quiet, and in the middle of nowhere in our airplane, the only company we have is our mind, so our senses become focused inside. Our emotions become much bigger and more powerful because they’re being amplified by solitude. During the day, we’re bombarded with visual input to occupy our thoughts and we talk to ATC more often. We are more likely to find ourselves alone with our thoughts at night. 

“I sit far back in my seat, my right foot braced comfortably against the instrument panel, listening to the steady thrumming of the engines, content to reflect…” 

– Ernest K. Gann  

In his August T &T article, David Miller talked about stress and how important it is to evaluate all conditions affecting our trip both before and during the flight. Especially if challenges seem to be accumulating. This includes the IMSAFE items, changing weather, developing fatigue and our anxiety. Your airplane doesn’t know or care that it’s dark. But due to our complex cornucopia of psychological and sensory ingredients, if flying at night, we should also consider how many bumps in the night we’ve heard from the ghoulies, ghosties and long-leggety beasties. Happy Halloween, my friends. 


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