Have you ever experienced SD?

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Joshua-0922

Filing Flight Plan
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Joshua Na
Long-time lurker, first post.
I'm a naval aviation trainee and an aerospace engineering student, and lately I've been digging into spatial disorientation in general aviation.

The stats are sobering, but stats don't tell you what it actually feels like in the seat.
So I'd rather just ask the people who fly:
- Have you ever had the SD, or a moment where your body and your instruments disagreed? What was the situation?
- For those of you flying legacy aircraft without an instrument rating — does the VFR-into-IMC risk change how or when you fly?
- If you've ever felt disoriented, what did you do, and did anything (training, avionics, habits) actually help?

I'm honestly just trying to understand the real-world version of this, not the textbook one. Happy to share back anything interesting I learn. If you'd rather not post publicly, feel free to DM — I'd genuinely value a few minutes of your time.

Thanks, and blue skies.
 
Ever play a game of dizzy bat or sit in a Barany chair? That’s a starting point.

The problem with Spatial D is similar to hypoxia; my signs/symptoms are unique to me/my experience and likely aren’t transferrable to yours.

Recovery is similar to any 12 step program; you have to first admit you have a problem, then be humble enough to do something about it. Admitting you have a problem is the step most fatals don’t get past.
 
I have experienced, in only 30hrs actual simulated, short period SD several times when turning via vectors or to an assigned WP on departure in IMC. This occurred when I was focused on instruments and flying by their cues. I had to stay focused and cognitively fight the urge to 'correct' the perceived attitude. It only lasted moments. It was truly sobering when it occurred. Although I have a little over 50hrs simulated, in my opinion, there are too many visual cues 'under the hood' to produce true SD. Get as much time actual instrument flying as you can.
 
Twice, as far as I can remember. Both on moonless nights at rural airports. Both times just after rotation. Pitching up into the black my head started swimming. Both times training and common sense took over. I knew I hadn’t overcorrected in that short amount of time, so “don’t make any sudden moves”, then onto the instruments to make sure the wings were level, etc. A sudden, unexpected, transition from VMC to IMC were my SD experiences.
 
The worse I've ever had was while training on my long IFR cross country. It had been a long day, as the cross country itself was far longer than necessary because we used it to complete another mission, two birds one stone kind of thing. In order to get that extra approach, we picked an airport along the route home to shoot an approach. It had been IMC the whole trip, which was good training but a little draining, especially with no autopilot in that aircraft. During the approach, I found my head leaning on the pilot's side window convinced I was in a turn. I fought the sensation and kept laser focused on the instruments until we broke out. Once we departed that field, I got my bearings back and the rest of the trip was uneventful.
 
Nothing serious enough to consider to be true spacial D, but I am very careful when IMC to make slow and deliberate head movements, especially when needing to look downwards. Keeping the head stationary (as much as feasible) and using the eyes as much as possible to look around the panel seems to be effective combating spacial D.

The closest I've come to experimenting spacial D was easily dealt with by believing the instruments. On a long daytime flight in solid IMC suddenly broke out in the clear between layers.

Both layers were maybe one or two thousand feet apart, and oriented perfectly parallel with each other, except they were both about 20 to 30 degrees off the horizon, yet the plane was still accurately showing level flight. Not exactly spacial D, but a very weird feeling on the onset, however it was easily handled by believing and flying the instruments.
 
Worst I ever had it was my first solo takeoff into imc after getting my rating. I had just entered the clouds and turned to my assigned heading... and my body started screaming at me that the plane was rolling over. Steam gauge Archer with no A/P. Thankfully my instructor's voice echoed in my head "trust the instruments". I cross checked everything to make sure the AI wasn't falling. That was the first time i understood how people lose control in imc.

Since then, I've had it a couple times, usually on takeoff turning to a heading or looking over at the engine monitor. Never as bad as that first time. I've got about 100 hours actual, all in piston singles.

I also had an attitude indicator fail in imc once, in that same Archer. It was REALLY hard to ignore it. I was really proficient partial panel then; wouldn't want to try it now.
 
I have had the somatographic illusion- accelerating into the clag, thinking I've gone nose up, it was POWERFUL. Resisted pushing the yoke which is what happens....but finally reduced power. Leans are VERY real, too....especially when at the edge of a shelf cloud- ONE end IS HIGHER than the other.
 
Jim K said:
I also had an attitude indicator fail in imc once, in that same Archer. It was REALLY hard to ignore it.
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Yes, for sure. I've had a couple of vacuum Attitude Indicators fail, and a vac powered HSI. Only the HSI failed IMC, but needed a let down through a cloud layer during one of the AI failures.

I keep a pair of Sporty's round suction cupped backed instrument covers pinched between an overlap in the side plastic interior panels within easy reach... covering up failed instruments makes a world of difference!
 
Rick A said:
Yes, for sure. I've had a couple of vacuum Attitude Indicators fail, and a vac powered HSI. Only the HSI failed IMC, but needed a let down through a cloud layer during one of the AI failures.

I keep a pair of Sporty's round suction cupped backed instrument covers pinched between an overlap in the side plastic interior panels within easy reach... covering up failed instruments makes a world of difference!
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The hardest part was figuring out what was going on. It was a very slow failure. After fighting with my brain for a few minutes and confirming it was bad, I remembered this was a training plane, and managed to dig out one of those covers from the right side map pocket. I resolved to never fly steam gauges without one of those handy.
 
How about yesterday? :) I was being vectored in IMC and could swear I was turning to the left when the AI and TC said was I was wings-level... had to repeat to myself "trust the instruments".
 
If you can get to Oklahoma and do the high altitude hypoxia training which is free they have a simulator that spins around in a circle and they can create the effect for you it is an absolutely awful feeling when they tell you there's a pencil on the floor you need to lean over and pick up.

Edit, to clarify: it's an enclosed simulator with no windows or view to the outside and they start to spin it and you sit there until you can no longer detect the rotation. You fly a little flight Sim computer game. You have no idea that you're spinning or how fast. It feels perfectly normal. They have you look down and it feels like you're about to fall out of your chair and your brain just can't reconcile how you feel versus what you're seeing it doesn't matter.
 
Joshua-0922 said:
Long-time lurker, first post.
I'm a naval aviation trainee and an aerospace engineering student, and lately I've been digging into spatial disorientation in general aviation.

The stats are sobering, but stats don't tell you what it actually feels like in the seat.
So I'd rather just ask the people who fly:
- Have you ever had the SD, or a moment where your body and your instruments disagreed? What was the situation?
- For those of you flying legacy aircraft without an instrument rating — does the VFR-into-IMC risk change how or when you fly?
- If you've ever felt disoriented, what did you do, and did anything (training, avionics, habits) actually help?

I'm honestly just trying to understand the real-world version of this, not the textbook one. Happy to share back anything interesting I learn. If you'd rather not post publicly, feel free to DM — I'd genuinely value a few minutes of your time.

Thanks, and blue skies.
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A few times when a CFI or Examiner deliberately induced it. Just once in the real world. I hadn’t flown in a few months and departed into low vis and ceiling. I was popeye before the field boundary and the body was telling me I was turning left/right, don’t remember. It took some will power to do what the instruments said.
 
My home airport (KPVC) is next the the ocean and the first time I turned crosswind toward the ocean on a cloudy day, it seemed like the ocean and the sky just merged into one formless continuous gray screen with no horizon. Suddenly I felt like I didn't even know up from down. It was eerily unlike any sensation I had ever felt - like I was detached from any sense of balance. Fortunately my training kicked in and I just continued pretty normally with reference to instruments until my turn brought me back to sighting land 10 or 15 seconds later. Now I know to anticipate this happening on such days and it's just routine.
 
Never had it for years handflew six pack turboprops to mins all that jazz.

One day taking a 737 out of gulfport at 500 ft my body was screaming we were 120+ degree bank even felt the weight on my shoulder straps. I just worshiped the flight director for a solid 10 seconds then mashed the autopilot and it went away. Its why i wont do recreational ifr 4k hours of trouble free flying and i suddenly struggled hard with a stable nicely equipped jet. Take a piston twin and a 6 pack at night throw in a sneaky instrument error and i could be a smoking hole.
 
Worst case of the leans by far, and really the only bad time, was a number of years back when leaving a small uncontrolled rural airport from a vacation property, with my wife. It was just after dusk, with an overcast at 5000ft or so and otherwise a quiet weather evening, with little wind on the ground.

I filed IFR, and as usual was going to pick up the clearance in the air, there is no radar coverage below 3000ft.

Took off to the east, and that area is completely featureless with little to no lights, there was no apparent horizon, and obviously no stars.

At about 1000ft in the air, hit severe turbulence. I honestly lost entire sense of up & down, just felt like I was rolling. I was on instruments as usual, and I'm comfortable with them, but even so it took all my concentration to follow them. That continued for a couple thousand feet, and then we exited into calm skies. I picked up my clearance, and we turned on course.

My wife is a very good flyer, she didn't say a word through this. I asked after we were settled on course what she thought about all that, and she related that she thought we were upside a few times and doing somersaults.

The real twist to this story, is that this would have been perfectly legal to fly as night VFR! Someone not proficient on instruments would have surely perished.

* Orest
 
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Back when I was working on my Commercial ASEL I needed some instrument training towards it, so my instructor put me under the hood and started with a set of steep 720s each direction. For the next couple of hours I was no less than 30 degrees bank away from what the airplane was, fixating, chasing, all the stuff you’re not supposed to do, and hanging on by the skin of my teeth. When he finally had me try to track the NDB to the airport, I got smart and slowed down enough for gear and partial flaps (one of the magazines had recently had an article that suggested that) and was a little better. My instructor also realized at that point that I was struggling as much as I said I was. ;)

After we landed, I had to concentrate to walk, probably shouldn’t have driven home, and sat down to study. After about 15 minutes I realized that I hadn’t been able to pull a single word off the page, so I went to bed.

Other than a few minor instances that went away in seconds, I haven’t had problems since.

As far as legacy aircraft without (or with) an instrument rating, I recommend the U of Ill/ASF technique for inadvertent IMC that involves a planned trim/power/gear/flap configuration, hands off the yoke, and keep the T&B needle centered with rudder. Of course, that assumes you’ve got a T&B. But I’ve known a few old-timers who survived because they had been to that seminar.
 
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Joshua-0922 said:
Long-time lurker, first post.
I'm a naval aviation trainee and an aerospace engineering student, and lately I've been digging into spatial disorientation in general aviation.

The stats are sobering, but stats don't tell you what it actually feels like in the seat.
So I'd rather just ask the people who fly:
- Have you ever had the SD, or a moment where your body and your instruments disagreed? What was the situation?
- For those of you flying legacy aircraft without an instrument rating — does the VFR-into-IMC risk change how or when you fly?
- If you've ever felt disoriented, what did you do, and did anything (training, avionics, habits) actually help?

I'm honestly just trying to understand the real-world version of this, not the textbook one. Happy to share back anything interesting I learn. If you'd rather not post publicly, feel free to DM — I'd genuinely value a few minutes of your time.

Thanks, and blue skies.
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WHEN I WAS CURRANT FLYING BACK IN THE 90,S HAD SOME REFERENCE TOO INSTR WORK WITH A CFI FRIEND.GOT THE C-152 INTO A SPIN AND THAT MOMENT WAS SD BIG TIME.WENT FROM 3500 AGL TOO 1200 AGL BEFORE RECOVERY.LOVE FLYING BUT THAT WAS MY MOST FRIGHTFUL MOMENT. MARK 63 YR OLD PRIVATE PILOT CURRENTLY PLANNING RETURNING TOO THE LEFT SEAT MAYBE??
 
Mileage said:
My home airport (KPVC) is next the the ocean and the first time I turned crosswind toward the ocean on a cloudy day, it seemed like the ocean and the sky just merged into one formless continuous gray screen with no horizon. Suddenly I felt like I didn't even know up from down. It was eerily unlike any sensation I had ever felt - like I was detached from any sense of balance. Fortunately my training kicked in and I just continued pretty normally with reference to instruments until my turn brought me back to sighting land 10 or 15 seconds later. Now I know to anticipate this happening on such days and it's just routine.
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I HAD THE SAME EXACT SITUATION AT MY AIRPORT KHAF IN NORTHERN CALIF ON THE COAST 5NM SOUTH ON SAN FRANCISCO.KNOW THE FEELING AND I TOO HAD MY TRAINING KICK IN AND WAS FINE.CONTINUED DOING MY T/GO PRACTICE.
 
Once. I was flying the mighty TH-67 in flight school doing the VOR rwy 18 into Eufaula AL. I was in the clouds in a descending right turn when my IP directed my attention to the overhead panel for some switch. I lurched my head up and looked left and said “yeah that’s fine.” When I looked back at the panel, my whole world was spinning. I should’ve tapped out and transferred the controls but I was worried about my grade. Instead, I released pressure on the cyclic and collective and let the aircraft do its thing until I gathered my bearings. I always tell people the statement “trust your instruments” is silly. I knew my instruments were right. I was do disoriented, I had to convince myself blue side should be on top of the AI and not on the bottom. After probably 30 secs of letting the aircraft do its thing, I grabbed the controls again, intercepted my inbound course and countinued the approach. During “table talk” back at Cairns, my IP asked why he brought up the position of a useless switch during the approach. He did it intentionally to try and induce SD (Coriolis Illusion). It worked perfectly.

Oddly enough, over the next 12 yrs of my Army career, the only time I ever saw anyone get SD was at night. Never in the clouds. It was at night, no ground lights, no moon and no NVGs. Fortunately both guys were smart enough to transfer the controls to me and not try and keep a secret.
 
Thanks so much for the reality check, everyone. These stories are worth a hundred textbooks.
Now I'm convinced that spatial D is crucial problem, especially for legacy aircraft pilots. And relying on instruments could not be perfect solution!

Your feedback actually pushed me over the edge.
Actually, I lost my comrade pilots in maritime helicopter accident because of SD.
To save the pilots, I'll strive to develop a portable safety device aimed at detecting spatial D and alerting the pilot.

I’ll start a new thread in a couple of days to ask a few specific questions about form factors (vibration vs visual) and what you'd actually be willing to use. Thanks again for the mentorship!
 
Joshua-0922 said:
Thanks so much for the reality check, everyone. These stories are worth a hundred textbooks.
Now I'm convinced that spatial D is crucial problem, especially for legacy aircraft pilots. And relying on instruments could not be perfect solution!

Your feedback actually pushed me over the edge.
Actually, I lost my comrade pilots in maritime helicopter accident because of SD.
To save the pilots, I'll strive to develop a portable safety device aimed at detecting spatial D and alerting the pilot.

I’ll start a new thread in a couple of days to ask a few specific questions about form factors (vibration vs visual) and what you'd actually be willing to use. Thanks again for the mentorship!
Click to expand...
The Army research lab was experimenting with tactile cues years ago. Basically used a belt around the waste that vibrates in certain areas to assist in maintaining orientation. Never made it out of testing phase.
 
Velocity173 said:
The Army research lab was experimenting with tactile cues years ago. Basically used a belt around the waste that vibrates in certain areas to assist in maintaining orientation. Never made it out of testing phase.
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That would've been super helpful if it worked.
 
It's happened twice to me that I recall.

First one was 9/11/2008, I remember that flight specifically. I'd been flying for just over a year, and had probably 150 hours or so at that point. Night IMC (so no visible horizon or ground reference whatsoever) in a Mooney with steam gauges, and I got the leans, hard. I forget which direction my body was telling me the plane was going, but it was not the direction indicated by the attitude indicator (straight and level). There was a very hard mental urge to trust my body (which keeps me upright). However, "Trust thine instruments lest the earth rise up and smite thee" went through my head on repeat. It went away after a couple of minutes, and didn't return. I had been in IMC for a bit, so it wasn't like I hit IMC and it instantly happened.

The second one was in the MU-2 which would've been sometime in the 2018-2020 period, and when I had a bit over 3,000 hours and around 450 hours of actual instrument time. Again steam gauges, but this was daytime. There was something very odd with the clouds (which weren't particularly thick, more of a haze almost) that made it look like there were clouds out the left side of the plane, and was clear out of the right side. In other words, it looked like I was banked over 90 degrees. That time, the leans urge wasn't nearly as strong (and it was nowhere near the difficulty to mentally follow my instruments), but the illusion of the horizon provided a very odd sensation. Kept on flying the plane, and it stopped again after a few minutes.

My best advice, make "Trust thine instruments lest the earth rise up and smite thee" your mantra in such situations, and maintain proficiency in flying in IMC, and especially hand flying rather than just letting the autopilot do it all.
 
Doing Dizzy Izzy's at NROTC field days got me through the Spin and Puke at Pensacola. To date, no Spatial Disorientation. I suggest everyone do the same.

NOT!
 
Student pilot 1st night lesson. Home airport is by the ocean on a moonless night. Chief pilot says to my CFI take him out over the harbor so he can see what it feels like with no horizon. I'm all in on becoming a pilot so I want to drink from the firehose. I didn't know what was in store. We cross the coast line into the black hole my CFI throws his pen on the floor and says grab that for me. When I sat back up and looked into that black hole and I would have sworn we were nearly inverted and diving for the ocean. Didn't last long, but man was it eye opening.
 
Velocity173 said:
The Army research lab was experimenting with tactile cues years ago. Basically used a belt around the waste that vibrates in certain areas to assist in maintaining orientation. Never made it out of testing phase.
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Oh, why TSAS technology didn't come to market? Expensive? Or STC
 
Joshua-0922 said:
Oh, why TSAS technology didn't come to market? Expensive? Or STC
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No idea. This was one the TSAS vests these they were testing when I was in. Years later it was reduced to a belt. I’m sure USAARL is still developing something but I don’t think today it has as much priority as 20+ years ago.

Army Aviation seems to be putting more weight into automation to overcome degraded visual environments (DVE) vs tactile cues. UH-60M / CH-47F now have full axis APs that’ll fly IAPs down to 10 ft. Even for dust landings / take offs, it won’t be long before that’s taken out of the pilot’s hands.

 
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1) I have a permanent case of the leans. I tilt my head to the left when on instruments and all is fine. Even in the sim I did this. :)

2) I launched on the wing in the A-10 for a air-to-ground sorties with heavy weights (practice 500 pound bombs) into the weather. We could no recover to the home base without dropping the heavy weights, and the cloud bases were too low to be descended below them by ATC. At one point I could have sworn we were on a vertical up line doing rolls. I know the Hog can't do that, but it was powerful. I took a quick glance at the AH and that stopped the feeling. BTW we found another range to drop the ordnance.

3) My primary instructor related one that happened to him. He was delivering a Citabria to the west. He wanted to get in one more leg after dinner so he took off on clear VFR night. But recently most of his night flying had been in the East with lots of lights on the ground and not so many stars visible. Out west, there are not so many lights on the ground and lots of stars visible. So he had to fight the desire to roll inverted to make more lights to be down.
 
Ever use something and it worked perfectly… and only a moment later it just won’t damn work?

You just keep hitting buttons in disbelief, double checking you’re doing it right, and you are, and it just won’t work?

And you’re just dumbfounded?

THAT is how it feels in the dangerous version…

Turns out, EVERYTHING works right up to the moment it doesn’t. But we just can’t figure out why it won’t work when it did a moment ago.

REAL spatial disorientation doesn’t really give you any clues, that’s how really good aviators fly right into the ground, in disbelief that their gyro isn’t right… or the plane just won’t fly correctly… etc.
 
bbchien said:
I have had the somatographic illusion- accelerating into the clag, thinking I've gone nose up, it was POWERFUL. Resisted pushing the yoke which is what happens....but finally reduced power. Leans are VERY real, too....especially when at the edge of a shelf cloud- ONE end IS HIGHER than the other.
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This is exactly what took out the commanding officer (no rookie) of one of the F-18 squadrons in my airwing.

Flight of two, popped off a low level, took splits, got clearance and climbed into a low overcast. Two jets went in, one came out on top…

I think they determined he hit a paltry 10 deg nose low and about the same angle of bank.

About certainly had no idea he had it… had our Admiral (a surface warfare officer) in his backseat. The other jet was CAG and DCAG…. They were going to St Louis to preview the super Hornet.
 
falconkidding said:
Its why i wont do recreational ifr 4k hours of trouble free flying and i suddenly struggled hard with a stable nicely equipped jet. Take a piston twin and a 6 pack at night throw in a sneaky instrument error and i could be a smoking hole.
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Good man. Recreational IMC kills with impunity. It's a novelty for the neophytes, otherwise a "flex" nobody is impressed with. Back in the pre covid years of milk and honey when I could afford an airplane on half the money I make today, I eventually installed a second AI, as the hypocrisy of harping about the stupidity of N-B-A, while relying on a turn coordinator myself when the primary went Tango uniform, got to be too much. I plain got lucky during my younger years, those were some stupid stunts I did behind a single attitude indicator. username checks!
 
Joshua-0922 said:
Thanks so much for the reality check, everyone. These stories are worth a hundred textbooks.
Now I'm convinced that spatial D is crucial problem, especially for legacy aircraft pilots. And relying on instruments could not be perfect solution!

Your feedback actually pushed me over the edge.
Actually, I lost my comrade pilots in maritime helicopter accident because of SD.
To save the pilots, I'll strive to develop a portable safety device aimed at detecting spatial D and alerting the pilot.

I’ll start a new thread in a couple of days to ask a few specific questions about form factors (vibration vs visual) and what you'd actually be willing to use. Thanks again for the mentorship!
Click to expand...
Why especially for legacy aircraft pilots?
 
hindsight2020 said:
I plain got lucky during my younger years, those were some stupid stunts I did behind a single attitude indicator.
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Yes, ditto. I thought I had the single AI issue beat early. The very first improvement following the purchase of an IFR capable travel machine was an emergency vacuum source powering the AI and DG from a small tube hooked up to a hole drilled into an intake manifold tube. So smart, the single AI issue was solved without spending big bucks for a backup electric AI.

Noting the change in engine RPM when the actuation lever was flipped was a part of the pre-flight check, confirming it’s operable.

This popular and simple inexpensive backup included a big bright red panel light that lit up informing a pilot to flip the lever on the standby vac before the gyros spooled down.

Sounded bulletproof until the vacuum pump died many many years later. Cruising between layers the red light lit, flipped the lever and couldn’t raise enough vacuum even following a huge reduction of power to spin the gyros anywhere near the vacuum necessary. Descended through the layer using the turn coordinator, and no big deal.

Upon inspection, the hole in the intake tube didn’t line up properly with the tube affixed to it. Enough vacuum was created to change RPM on the ground, but not enough to adequately spin the gyros in flight. Following that event the next panel upgrade included a full sized electric AI, mounted front and center, just to the right of the altimeter.

Remembering the amounts of takeoffs into low ceilings and near instant immersion to instrument flight I realized how lucky this young and fearless instrument pilot had been.
 
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