From watching shows like “Air Craft Investigation,” I’ve learned that some air crashes are caused because the pilot can’t see the horizon, has no visual orientation cues, and doesn’t realize s/he is starting to bank to one side. In some cases, the pilot is so certain s/he is flying straight that even when the horizon instrument indicates a bank, and warning signals go off, it is dismissed as a faulty instrument reading.
When I’ve been on a plane as a passenger, I can tell the plane is banking because I feel the effect of my body moving against the seat or against my lap belt in one direction. If there is a drink on my tray table, I can see the liquid “leaning” in the glass. My question is why pilots can’t also “feel” the force of the bank against their bodies, and why don’t planes simply have a regular $5 level stuck to their cockpit so if they think their instrument is wrong, they can look at the level. Does a level not work at altitude? It’s hard for me to understand how a pilot can become so disoriented.
Thank you for that fascinating video. Now, can you explain to me how this happens? I don’t know anything about aeronautics or enough about physics to understand why normal rules of gravity don’t seem to apply.
Well, I’m not an expert and will probably botch a detailed explanation, but simply there are more forces on the pilot than just gravity. The pilot is also affected by the acceleration, inertia, and if rotating the centripetal force of the plane, and sometimes the interaction of those forces can fool your inner ear.
For instance, if I’m in my plane and I’m climbing at full power and then I reduce the power it will feel like I’m falling even if I’m still climbing because I’m not climbing as fast. If I’m flying at a constant speed it feels to my body that my plane is at rest even though I’m moving at 150mph.
I’m not enough of a physicist to understand the details of centrifugal force and rotating frames of reference and all that, but in the video the centrifugal force applied to the cup of water and the pilot made it seem that the plane wasn’t rotating at all. The “downward” force was always 1G directly through the floor no matter if the floor was pointing directly at or away from the ground.
Yes, I figured out that centrifugal force kept the ice tea glass from emptying when the plane was upside down, but I’m still stunned by the flow from the pitcher being entirely unaffected by the turn. Thanks for your response. It’s a really interesting phenomenon that’s hard for lay people to understand.
I think that, at some point, most of us, pretty early on, had our flight instructor tell us to close our eyes and tell him what we thought he was doing with the plane. Your inner ear and body register some forces, but in a few seconds you don’t know what the hell is going on.
Mine, before telling me to open my eyes, asked what attitude I thought we were at. I said (because I felt) “straight and level.”
“Open your eyes.”
We were in a dive, with the right wing dropping.
That was pretty much all the training I needed to understand the “always trust your instruments” lecture.
Here’s Tex Johnson, discussing a barrel roll in a 707 and he remarks that it is a 1g manuever. In the Aerocommander, Bob Hoover is doing the same thing. The fuselage of the aircraft is following the walls of a barrel through the sky so the 1g vector is always perpendicular to the bottom of the fuselage. This is a different maneuver from an aileron roll where the aircraft is rotating about its longitudinal axis.
A bank is the same, once your body adjusts to the acceleration and without a visual reference, you will think that you are in level flight. In fact, going from, say, a right hand bank to wings level can cause the vestibular system to sense that you are now actually turning left instead of level. Without instruments, you try to correct and it is this sensory feedback that leads to pilots entering a deadly graveyard spiral.
Disorientation occurs when your senses tell you one thing and the instruments tell you something entirely different. Pilots are taught that their instruments are always more accurate then their senses. There are other clues available, like engine sounds and wind noises, but you really can’t tell a turn from straight and level flight.
JFK Jr. had this particular problem on his fatal flight. He flew at a time when it was dark and overcast to the point he could not make out the horizon. He didn’t have sufficient instrument training to trust his instruments and he was unable to maintain control of his aircraft.
It all comes down to the inner ear not being a reliable flight instrument. Google vertigo for more info on it.
If you inadvertently fly into IMC without instruments training, you will very soon enter a “graveyard spiral”. Less than three minutes later, you will open your mouth to scream but it will be too late. Or so I have read.
The one time I got disoriented was on a training flight for my instrument rating. I was wearing foggles, which kind of look like safety glasses a scientist might wear, except with most of the lens frosted. The part right around your nose is not frosted so that you can look down at the instruments, but you cannot see anything else.
I was on an approach at less than 1,000 feet and descending. The weather was overcast, and just barely out of the corner of my left eye I could see trees passing below me. I think the sense of motion on my left made my brain scream at me, “We are turning but you’re supposed to be going straight!” After a few seconds, it wasn’t just my brain telling me I was turning. I swear I felt the plane banking. Then the confusion set in: why are the instruments telling me I’m going straight?!?
Knowing that I was less than 500 feet off the ground, with my body and brain telling me that I was turning, yet my eyes registering that I was level, was as confusing as taking a sip from a can of Coke and tasting orange juice. It just didn’t make sense. Fortunately, my flight instructor saw what was going on and told me that I was disoriented. Moments later, at a couple hundred feet, I “broke out of the clouds” (took off the foggles) and saw the runway right where it was supposed to be.
But seriously, that sort of disorientation is so confusing that just saying “trust your instruments!” comes across as, “sure, you’re underwater, but just take a deep breath!”
The key thing is your ear can sense roll & acceleration in rate of roll. It can’t directly sense bank.
So as a pilot or passenger you can feel the aircraft enter a turn. But you can’t feel it IN a turn. The sensation of straight flight and the sensation of steady turning are identical. And the sensation of entering a, say, left bank from wings level is EXACTLY the same sensation as leaving a right bank and returning to wings level.
Finally, your angle rate sensors aren’t very sensitive. So if the airplane is very slowly & gently increasing bank to, say, the left, you have zero sensation of this. And if the airplane then more abruptly rolls back to wings level, i.e. rolls rightward, your sensors detect that and say “we’re banking right”. Now your mind believes it felt a transition from wings level to right bank when in fact the transition was from left bank to level. That is a recipe for serious, possibly life threatening, confusion.
In addition, vibration pumps a bunch of noise into the subtle signals from your sensors. Which makes them even less sensitive than they’d otherwise be.
You’re of course familiar with being dizzy. And how the room appears to be rotating, but somehow isn’t becoming more tilted over time. How can it seem to you to rotate and yet seem to not rotate at the same time? The answer is your brain is taking in two signals from different sensor systems, one of which is being fooled and one of which is not. And your brain struggles mightily to make sense of conflicting inputs it wasn’t designed to handle.
A problem is that an output from that system is used to stabilize the image your eyes feed into the brain. If that gets confused enough you simply can’t see. Or more accurately, you have light & color & shape just like always, but can’t convert that into a meaningful concept.
If you’ve been really drunk you’ve probably experienced a pretty near analog of this. You’re thinking “I see it, but I can’t make sense of it” for whatever"it" you’re looking at.
It’s surprising easy when the aircraft is flying a curving path to induce a touch of dizziness. All it takes is a quick movement of your head in another plane of motion. And it doesn’t take much dizziness to multiply your other sensory confusions by a huge margin.
The rule is:
If you, as a VFR (Visual Flight Rules) pilot, continue into a cloud, start counting down from 7.
That’s how long you’ve got to live.
A study in UK took the usual human lab rats (college students) and put them in flight simulators (real ones) and got them to the point that stick and rudder were coordinated, and they could fly to any given destination they could see.
Then they flashed the white-out display and timed the reactions,
Every one of them screwed into the ground. Average time: 7 seconds.
Every factory-built has the following:
Magnetic compass *
Altimeter *
Airspeed *
Vertical Speed (you rising or falling. and how fast?)
Artificial Horizon (gyroscopic)
Directional Gyro (“Gyro compass”) - a rotating compass display
See any pic of a small plane panel - typically, all but the magnetic compass is a 3" display directly in front of the pilot.
In order to auger in as so many do, you need to ignore:
Compass spinning
Horizon spinning
DG spinning
VSI is pegged in the downward direction
Airspeed is approaching red line
Altimeter (clock with 3 hands) is unwinding
Modern planes now have voices screaming - bigger planes will take control and try to recover.
The pilots are now desperately trying to shut off the damned noise and dis-engage the autopilot.
We really aren’t designed to fly.
I had one instructor who wanted to cover the panel - don’t look there - look outside!
Actually, twit-about-to-be-unemployed, I can do both.
There is a reason why those particular instruments are in the plane, and why they are placed where they are.
Late add:
Professional pilots have strategies to deal with these shortcomings in human capability. And we get to experience the conflicting stimuli often. Which helps us to get better at ignoring the conflicting inputs. But it’s 100% normal to spend a few seconds on every bad-weather flight actively fighting sensory illusions. IOW it’s not something professionals “get over” having. It’s something they have every workday but learn to “get past.”
There’s a particular departure out of Sydney that I fly regularly at night and I frequently get “the leans” during it. It’s basically a 30° turn at the end of the runway onto about a 15° intercept of the outbound track. The turn on to track is very subtle and we are simultaneously retracting flaps, changing pitch attitude and accelerating in airspeed. My poor brain fights it all the time.
I keep hearing from aviation experts and pilots on TV that if turbulence gets severe then the auto-pilot shuts off so the pilot can take over. It seems to me that in a storm or at night, this is when you want the auto-pilot doing the flying. Especially in a stall in zero visibility it seems like the auto pilot should be doing the recovery, not the human pilot.
The important rule of physics here is that objects (and liquids) respond to the net of all forces acting on them. Gravity is operating in the normal way, but (except when traveling in a straight line at a constant speed) an aircraft is imposing accelerations of its own.
You can easily demonstrate this for yourself: fill a bucket with a couple of inches of water, tie a string to the handle, and move the bucket in various directions holding the string. Notice how easy it is to get the surface of the water non-horizontal. It’s actually not difficult to swing the bucket over your head so it’s briefly upside-down, with the water staying happily in the bucket the whole time.
A whole lot of factory airplanes do not have all those instruments. They are not new planes but they are legal to fly.
Compass can spin
DG can spin
AH or turn indicator starts spinning, jump out because the goblins are gonna get you. ( Not the fancy fighter aircraft AH but most anything that would be in a small aircraft will not spin. )
WW1 aircraft did not have many instruments. A lot of them, can descend through several thousand feet of cloud and fly away under the clouds if there is room just fine.
Big iron, not so much.
An old straight back C-150 can let down through 5000’ of cloud / W rain with just the standby compass, altimeter ( good for progress checks but not really needed ) and the ball in the tube part of a Turn & Bank set up.
Carb heat, flaps, and
“much unbroken concentration no matter what your head is saying.”
And your ears for hearing only.
Not recommended but it is doable.
Some get disorientation for only short duration and some have it almost constantly. Those types never have to worry about getting disorientation because they always have it. Having to learn instrument flying with this conditions makes you very hard to mess with on a check ride because you are way ahead of the check pilot. LOL
Pilots, I have a question, is this a good analogy?
You drive at 75 mph on the interstate for a few hours. Get off and drive through town and you swear you are crawling at 30 and you are really doing 50.
The explanation I heard from my physics professor in college was that if the airplane is flying in such a manner that it feels like 1g (that is, 1x the Earth’s gravity force,) then, even if the airplane is banking in a spiral, its centrifugal force could make the pilot feel like he was flying at 1g, level and stable. Thus, a pilot flying in the dark could crash while all the while thinking he was flying straight and level.
