Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

Spatial Disorientation

Wikiposts
Search
Rotorheads A haven for helicopter professionals to discuss the things that affect them

Spatial Disorientation

Thread Tools
 
Search this Thread
 
Old 23rd Jan 2005, 16:12
  #1 (permalink)  
Thread Starter
 
Join Date: Aug 2000
Location: England/Arizona
Posts: 118
Likes: 0
Received 0 Likes on 0 Posts
Spatial Disorientation

Following a chat amongst us today about helicopter crashes and spatial problems I thought I would post this article as a thought provoker to all of us who fly and maybe have not considered the problem enough since our PPL days or who have been flying so long we think we are too experienced to get into trouble.



How long can a pilot who has little or no instrument training expect to live after he flies into bad weather and loses visual contact? Researchers at the University of Illinois did some tests and came up with some very interesting data. Twenty student "guinea pigs" flew into simulated instrument weather, and all went into graveyard spirals or rollercoasters. The outcome differed in only one respect - the time required till control was lost. The interval ranged from 480 seconds to 20 seconds. The average time was 178 seconds -- two seconds short of three minutes.

Here's the fatal scenario. . . . . . .



The sky is overcast and the visibility is poor. That reported five mile visibility looks more like two, and you can't judge the height of the overcast. Your altimeter tells you that you are at 1500 feet but your map tells you that there's local terrain as high as 1200 feet. There might be a tower nearby because you're not sure how far off course you are. But you've flown into worse weather than this, so press on.

You find yourself unconsciously easing back just a bit on the controls to clear those towers. With no warning, you're in the soup. You peer so hard into the milky white mist that your eyes hurt. You fight the feeling in your stomach. You try to swallow, only to find your mouth dry. Now you realize you should have waited for better weather. The appointment was important, but not all that important. Somewhere a voice is saying, "You've had it -- it's all over!"


You now have 178 seconds to live.


Your aircraft feels on even keel but your compass turns slowly. You push a little rudder and add a little pressure on the controls to stop the turn but this feels unnatural and you return the controls to their original position. This feels better but now your compass is turning a little faster and your airspeed is increasing slightly. You scan your instruments for help but what you see looks somewhat unfamiliar. You're sure that this is just a bad spot. You'll break out in a few minutes. (But you don't have a few minutes left. . .)


You now have 100 seconds to live.


You glance at your altimeter and you are shocked to see it unwinding. You're already down to 1200 feet. Instinctively, you pull back on the controls but the altimeter still unwinds. The engine is into the red and the airspeed, nearly so.


You have 45 seconds to live.


Now you're sweating and shaking. There must be something wrong with the controls; pulling back only moves the airspeed indicator further into the red. You can hear the wind tearing at the aircraft.


You are about to meet your Maker; you have 10 seconds to live.


Suddenly you see the ground. The trees rush up at you. You can see the horizon if you turn your head far enough but it's at a weird angle -- you're almost inverted. You open your mouth to scream but. . . . . .


. . . .You just ran out of seconds.


Think about it before you press on into marginal weather



This Test was carried out with a Fixed wing, I have been told that for a rotary the average time is reduced to just THIRTY seconds.
Banjo is offline  
Old 23rd Jan 2005, 16:16
  #2 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,287
Received 507 Likes on 210 Posts
You saw my last IRT ya bugger! Don't spread it around!
SASless is offline  
Old 23rd Jan 2005, 16:31
  #3 (permalink)  
Passion Flying Hobby Science Sponsor Work
 
Join Date: Apr 2004
Location: Belgium
Age: 68
Posts: 461
Likes: 0
Received 0 Likes on 0 Posts
IFR ?

Banjo

"a pilot who has little or no instrument training"
survives THIRTY sec in a Heli ....

My guess would be THREE


delta3
delta3 is offline  
Old 23rd Jan 2005, 17:06
  #4 (permalink)  
Thread Starter
 
Join Date: Aug 2000
Location: England/Arizona
Posts: 118
Likes: 0
Received 0 Likes on 0 Posts
Most of the accident reports/transcripts I have studied of UK heli crashes due to IMC flight tend to support the thirty or second so figure Delta 3. Either way it's not often you get to go home from it!
Banjo is offline  
Old 23rd Jan 2005, 17:45
  #5 (permalink)  
 
Join Date: Jul 2003
Location: uk
Posts: 1,041
Likes: 0
Received 0 Likes on 0 Posts
Perhaps if the average heli pilot flew higher than 300 feet they might have a few more seconds to live!
BigEndBob is offline  
Old 23rd Jan 2005, 18:21
  #6 (permalink)  
 
Join Date: Mar 2004
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
A few years ago I went on a visit to the AAIB. There was a slide show covering a number of accidents involving commercial helicopter pilots, fully instument rated, who had crashed due to bad weather.

They had tried to analyse why such accidents had occurred and the conclusion was that even though these pilots were very capable of flying in the bad weather, it was the transition from VMC to IMC which actually caused the problem.

If they were established on instruments they would not have a problem, but when the weather was bad but they were still just able to continue visually, and they then flew in to IMC that was when the trouble started.

As the cloud rushed by them, they instinctively pulled back, not initially realising they were climbing and the airspeed declining, after which it all started to go from bad to worse.

The message from the AAIB was that if you think you stand a chance of flying into IMC the important thing to do is to establish yourself flying solely on the instruments BEFORE it happens.

I seem to recall some figures somewhere that stated that if you flew into IMC you had something like 11 seconds before you adopted an unusual attitude, and 40 seconds before that unusual attitude became unrecoverable. Not long.

Shortly after the AAIB visit I was very close to home and pressing on in bad weather. I had a brush with IMC that could have easily resulted in me being added to the AAIB statistics. The combination of the AAIB visit and my own near disaster, has left me with a much greater respect for the weather.

In the face of other private pilots who wish to press on in dreadful conditions I am happy to say that I have adopted cowardice as means of survival which has stood me in good stead. I fully intend that if it turns out to be helicopters that kill me, it wont be because I was stupid enough to be flying in appalling weather conditions.
Anne Tenner is offline  
Old 23rd Jan 2005, 18:50
  #7 (permalink)  

Better red than ...
 
Join Date: Aug 2004
Location: Appleby-in-Westmorland Cumbria England
Posts: 1,412
Likes: 0
Received 0 Likes on 0 Posts
In the face of other private pilots who wish to press on in dreadful conditions I am happy to say that I have adopted cowardice as means of survival which has stood me in good stead. I fully intend that if it turns out to be helicopters that kill me, it wont be because I was stupid enough to be flying in appalling weather conditions.

Well said AT. There have been far too many accidents because of people flying when they did not need too.

Top tip #1. Dont get into the situation.

But if you did (God forbid) and are established on instruments what are then the best actions to take, discuss.
helicopter-redeye is offline  
Old 23rd Jan 2005, 19:28
  #8 (permalink)  
Thread Starter
 
Join Date: Aug 2000
Location: England/Arizona
Posts: 118
Likes: 0
Received 0 Likes on 0 Posts
Anne T. I would not be so hard on yourself and call it cowardice, more a sensible stand to take and a desire to return home at the end of a day to ones family and I for one applaud it.

As to your numbers another figure to consider would be that it takes a qualified and in practice instrument pilot approx 9 seconds to fully establish on instruments when not expecting to have to.

BigendBob, height sadly does not have much to do with it. 200’ or 2000’ the difference will in all probability not help you to sort out the problem once lost in IMC if untrained. In fact in a number of cases the flight path has become so erratic as to have caused a mid air break-up before the ground has even come into play.

The only way to prevent it, is as redeye has said, is to avoid getting into that position in the first place!!

We are not an aeroplane who would prefer to find a nice runway to land on. We can land almost anywhere safely and as such have no reason to keep pushing on into worsening conditions. Yet every year pilots keep killing themselves and their passengers because of get-there-itis. This will not change until we start to teach Captaincy to new pilots at a serious level as opposed to the lip service it gets in most PPL courses nowadays.

Along with this the more experienced pilots need to help teach the attitude that it is all right to not make a flight as opposed to the “a better pilot would have made it” attitude that sadly still prevails in some corners. Widows and orphans are attending funerals every year and will continue to do so for no other reason than someone could not make the simple decision to cancel or turn back from a trip instead carrying on following an already chosen course of action.

Redeye the question might better be “how can we teach pilots to be more flexible in their decision making process and improve their judgment so as to prevent them from placing themselves in such a position?”
Banjo is offline  
Old 23rd Jan 2005, 20:20
  #9 (permalink)  
 
Join Date: Sep 2000
Location: SE England
Posts: 275
Likes: 0
Received 0 Likes on 0 Posts
Surely a classic example; certainly an expensive afternoon.

http://www.juneaucrondahls.com/ships...02/cal0209.htm
September 10, 1999: A Temsco helicopter crashed on Herbert Glacier stranding five cruise ship passengers overnight in 25 degree temperatures and snow on the glacier. Two additional Temsco helicopters crashed on Herbert Glacier in an attempt to rescue the pilot and passengers on the first helicopter.
Smoketoomuch is offline  
Old 23rd Jan 2005, 21:02
  #10 (permalink)  
 
Join Date: Jul 2002
Location: Texas
Posts: 512
Likes: 0
Received 0 Likes on 0 Posts
Some years back the US Army did a test, using experienced instrument instructors and pilots, flying UH1s with a safety pilot. The objective was to slow the airspeed down by 10 knots at a time, and see how slow they could fly and maintain control. Some sort of instrumentation was used to record eye movements and where the eyes were looking. In every case, the scan had to be reduced as airspeed slowed and stability was reduced, and by the time 60 kts was reached the AI was basically all any of the pilots had time to scan, and below 60 knots every pilot went into a graveyard spiral and the aircraft had to be recovered by the safety pilot. If you fly into weather and have to go on the instruments, make sure you get the airspeed up immediately. The exact airspeed may differ by model, but the overall effect is likely to be the same, at least with helicopters without AFCS.
GLSNightPilot is offline  
Old 23rd Jan 2005, 21:48
  #11 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,287
Received 507 Likes on 210 Posts
GLS....

Is this the same Army that put out thousands of "Tactical Instrument Rated" pilots during a period of unpleasantness in the Southeastern part of Asia? The same Army that spent countless hours of valuable training time teaching the figure eight tactical instrument approach that was dead certain to cause veritigo and/or disorientation over,around, near, an NDB or Field radion transmitter? The same Army that lost hundreds of helicopters to weather related accidents and killed a swoop of people as a result of those policies invented by MGEN Tolson of 1st Air Cav fame and later a bigwig in the NCARNG?

Who got to ride home in the center seat of a pickup truck one afternoon because a young Army warrant officer would not violate regulations and fly a UH-1 from Charlotte to Raleigh IFR.....that same Army? (Was a proud holder of one of those wonderful TAC tickets.....and could not miss the opporunity to make a point....a Standard ticket would have prevented that problem....) We started getting Instrument school slots immediately after that as I recall.

There is something to the study...but I dare say 60 knots is a tad high.....also different aircraft will handle better if configured with stability augmentation than the old Huey...god bless her!
SASless is offline  
Old 23rd Jan 2005, 23:16
  #12 (permalink)  
 
Join Date: Jul 2002
Location: Texas
Posts: 512
Likes: 0
Received 0 Likes on 0 Posts
Same Army, just a later version. Maybe 60 kts is high, but below that no pilot was able to maintain control, IIRC. I can't find the study now, but another Army study on spatial disorientation is here . This is much more recent, and not the same type study, but it does show the risk of night flight, even with NVGs.
GLSNightPilot is offline  
Old 23rd Jan 2005, 23:35
  #13 (permalink)  
 
Join Date: May 2002
Location: Downeast
Age: 75
Posts: 18,287
Received 507 Likes on 210 Posts
I ran across this site a few nights ago...very well done accounting of US Army helicopter losses by type of aircraft. As you read through the UH-1 Huey portion of the site....during the Vietnam period....accident after accident shows up due to night and IIMC events. One thing to remember...lots of times the aircraft instrumentation was not operative, there was very little nav or radar available....and it was a very dark place with mountains in most parts.


www.armyaircrews.com
SASless is offline  
Old 23rd Jan 2005, 23:46
  #14 (permalink)  

Iconoclast
 
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
Posts: 2,132
Likes: 0
Received 0 Likes on 0 Posts
Thumbs up History repeats itself.

Many years ago a group of H-34s were flying one after the other in a long line. The lead pilot flew into a canyon and was suddenly enveloped in a cloudbank. The lead pilot redioed to the following pilots to come to a hover do a 180 and fly out of the canyon. Since the loss of visibility was progressive the other pilots still had some spatial reference. All got out of the situation except the lead pilot. He reduced airspeed to zero and came to what he felt was a stationary hover. The H-34 in a hover would hang down 3-degrees by the tail and seven degrees wheel down to the left. His instruments told him he was in climbing bank but his barometric instruments told him he was stationary. It didn’t take long for vertigo to start and shortly thereafter he crashed.

He did not have an ASE,which would have corrected for the hover attitude.


Lu Zuckerman is offline  
Old 23rd Jan 2005, 23:55
  #15 (permalink)  
 
Join Date: Jan 2004
Location: australia
Posts: 221
Likes: 0
Received 0 Likes on 0 Posts
This is fairly timely for me becase I found myself in this exact situation for real about two weeks ago. As a cautious pilot with a couple thousand hours I was flying a fixed wing aircraft under marginal daytime VFR, totally smooth air in light rain under a cloud base of only 1500 feet, terrain was up to about 300 feet in spots, the rain gradually got heavier until forward visibility was zero, could still see the ground OK, one minute later the ground was gone too and it was solid dark grey IMC murk and then it got bumpy. It seems I had flown into a patch of cloud cumulus off the edge of a biggish storm that went right onto the trees. I pushed on for about another minute hoping to pop out and it started to feel a bit weird and then decided it was all just too scary and turned around to get back out, had partial leans, almost instantly felt sick, nothing on the panel seemed to be matching up with what I felt in my guts. Felt like I was turning but wasn't, tried to get "level" in my guts, that made the AI turn me the other way. It is a disgusting feeling. Through luck I only spent a few minutes feeling totally out of control but finally came back out of the gloom and saw some ground and all the sicknesss vanished. Without any pride I can tell you I nearly messed myself during that few minutes. My encounter was honestly unintentional but guys and girls, just don't ever do it on purpose because it is an experience that you will really not enjoy. I was very lucky and learned my lesson. One thing that freaked me out is how engine noise seems to double due (to reduced optical sensation ?) and that just adds to the confusion. Looking at a clear AI image of a plane turning and honestly believing that you are straight and level is just horrible.

stay safe.

Vic
victor two is offline  
Old 24th Jan 2005, 01:35
  #16 (permalink)  

Not enough $$$ ...
 
Join Date: Jul 2004
Location: Brisbane
Posts: 317
Likes: 0
Received 0 Likes on 0 Posts
Simulator time, simulator time, simulator time, simulator time.

Simulate the leans in a non-motion sim by getting the instructor to replace one of forward views with one of the side front views with a downwards offset angle. Nothing out the front window makes any sense to your brain and the instruments become your best friend in the world.

No, I haven't tried this in real life, but after many hours of practice I have completed several hour-long IMC cross-country flights in the simulator with map reading, nav radio operation, etc, both in daytime and full black night settings, with wind buffeting, lightning and rain.

Note that I am not saying I would presume to be better than an ab initio pilot with no experience at all if I was flying a real aircraft, the point is this: it took me a good 10-12 hours of practice in instrument flying to be able to do that in the simulator (on top of the hundred or so hours of VFR sim time), and I pity any non-instrument-rated pilot who finds themselves inadvertently in IMC.

Even an EMS pilot I've spoken to lamented the lack of preparedness for black night bad weather operations, as have several Army pilots.
wishtobflying is offline  
Old 24th Jan 2005, 07:39
  #17 (permalink)  
Thread Starter
 
Join Date: Aug 2000
Location: England/Arizona
Posts: 118
Likes: 0
Received 0 Likes on 0 Posts
Victor Two I am glad that you are still with us.

It was fortunate that you flew a fixed wing that day a slightly more stable platform than a helicopter. Thank you for letting others know how easy it is to fall into such a situation. It is those pilots such as you who now have the ability to spread your story to others you meet in flying clubs and other places where pilots get together (bars, I believe they call them) and try to raise the awareness of ending up having to rely on instruments without the training. I am sure that you will not push the weather envelope again and risk a repeat flight.

Because you have the strength of character to tell your story as opposed to keeping it quiet for years you also can help other less experienced pilots gain the strength required to NOT make a flight.

For some reason pilots keep finding the decision to go an easier route to take than the decision to not go on a trip. Maybe someone here could point us in the way of any research into this decision making process.
Banjo is offline  
Old 24th Jan 2005, 08:01
  #18 (permalink)  
 
Join Date: Feb 2001
Location: Europe
Posts: 535
Likes: 0
Received 0 Likes on 0 Posts
In a rotary there is simply no reason to ever go inadvertently IMC, assuming VFR pilot and machine. Just go lower and slower, and when you get too low turn round and go back, or land. But what ever you do, never, ever, lose visual contact with the ground. And if you need to turn, do so to your side, (ie to the right in most helos) so you can keep the ground in your door window as you turn. End of story.

Victor two: you could have descended and slowed, and then turned back in VMC if it was deteriorating too much. No doubt because of their aircraft's inherent stability, and the fact they tend to fly higher, fixed wing PPLs tend to go IMC more often, but such an approach in a rotary is a recipe for disaster.

I believe too much emphasis is placed on the importance of some IMC training. You are either VFR in a VFR machine, or instrument rated in a IFR machine. A little knowledge can be a dangerous thing.

Just think, you don't take the "go lower and slower" rule far enough, and you get into IMC, what height are you going to be at? Less than 500 ft? Almost certainly - you'd be an even bigger idiot to end up in IMC higher than this. So, you're now IMC with the ground less (probably much less) than 500ft away. Assuming you can even do a big turn on instruments, the chances of losing 500ft in the process are pretty high. You may get lucky and control the airspeed and vertical speed well, but you've got every chance of boring a hole in the ground, even assuming you emerge a hundred or so feet above the misty ground.

Given the same initial situation, ie getting into IMC low level, (assuming ice is not an issue) our IFR pilot/machine would climb straight ahead at max IMC rate, get to MSA, and then decide where to go to get down again. Assuming he did this, our VFR pilot has no approach plates to refer to, no experience of making an IMC approach, probably limited fuel and a massive amount of anxiety. A pretty lethal mix.

Night poses greater risks of going inadvertent IMC, but then you've got to be much more cautious. Only follow routes with reasonable ground lighting, keep high, and always be wary of your visibility decreasing. If you could see a town 7 kms away and then it disappears, a big chunk of cloud has just got in the way. Descend until it returns in sight, then think sensibly what to do. Intermittent use of landing light to check for moisture is very valuable.
rotorspeed is offline  
Old 24th Jan 2005, 08:44
  #19 (permalink)  

Senis Semper Fidelis
 
Join Date: Feb 2001
Location: Lancashire U K
Posts: 1,288
Likes: 0
Received 0 Likes on 0 Posts
Pressonitiss seems to be some type of strange thing that make's normally sound thinkers into blinkered half wits,

Where I live we are surrounded by reasonable smooth yet hard rolling hills , part of the mid Pennines in the UK, many helicopters fly directly over my office/house in many different types of weather, you would be supprised at the amount of really good helicopters that fly low to keep in touch with mother earth, but then "just to get over the hill top" go IMC, with the Pylons and radio masts that also abound, many times have I held my breath waiting for that awful crump, and then silence!

These comparativly low hills, have captured many aircraft, and helicopters, flown by Pilots who should have known better, but yet took a chance!

Peter R-B
Vfrpilotpb is offline  
Old 24th Jan 2005, 09:00
  #20 (permalink)  
Thread Starter
 
Join Date: Aug 2000
Location: England/Arizona
Posts: 118
Likes: 0
Received 0 Likes on 0 Posts
Peter R-B couldn't agree more.

That is exactly why I believe the importance should not be on a small amount of instrument "appreciation" during the new JAA PPL (asking for trouble when mixed with the wrong personality) but in fact a sensible CRM/Captaincy type course to prevent flying into those conditions in the first place.

We have it in the commercial world when will(or how many have to die before) the CAA decide that PPl's should also attend such courses as part of gaining their licence.
Banjo is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.