Just so I do not cause unnecessary obfuscation on this thread - I am NOT suggesting that somatogravic illusion contributed to the accident - I just do not know - I am merely trying to help HN39 understand the phenomenon in view of the comments he/she has placed.

BOAC,
Right, like I said, applying brakes changes the perceived acceleration (GIA).

EMIT,
Thanks. I know all that.

EDIT::
Imagine a person swinging on a swing, eyes closed, moving rigidly with the swing, ignoring the wind and air resistance, what does he feel? He feels the rotational movement of his body (the somatogyral effect), he feels the GIA changing in magnitude, but the direction of the GIA relative to his body does not change, until you start braking the free movement of the swing. He could be standing upright without falling off.

EDIT2::
I am primarily responding to rudderrudderrat's post which dealt with the situation prior to stall. I'm not ruling out somatogravic illusions after the stall due to the dramatic increase of drag resulting from the stall.

- if you said "A somatogravic illusion can also be a false sensation of acceleration that results from perceiving as vertical the direction of non-vertical gravito-inertial acceleration or force" we'd be there!

PS A simulator has no wheelbrakes.so "applying brakes changes the perceived acceleration" just cannot happen. How else do you think you can "change the perceived acceleration"?

BOAC,

Are you being serious? Applying brakes on a moving airplane after landing changes the perceived acceleration. Since the simulator is stationary and has no wheel brakes, it changes the perceived acceleration by tilting the cab. Is that better?

Yes, much better. So you accept that a pitch attitude can produce a sense of acceleration - I began to think from your previous that you didn't.

In relation to "are you serious?" it was your post that made ME wonder and I think it was also Why disagree? You have just agreed!

I've never disputed that, nor have I disputed that somatogravic illusions can occur. What I'm arguing is that the combinations of pitch attitude and longitudinal accelerations that occur in maneuvers at more or less constant total energy (or at quasi-constant rate-of-change of total energy) - e.g. the swing analogy - do not result in somatogravic illusions.

PNF inaction : I found very strange that crew :

1 former Steward as CPT
1 former Air Traffic Controler as PNF
1 cadet as PF...

As the Controllers are not allowed to "suggest" actions to pilots, and that was his position for some years, when he got a pilot would he have been shy to "suggest" some actions to the PF ? (just an idea)

.....not a lot 'odder' than any other explanation we have so far, Rouli. I do, however, feel that the preservation instinct would kick there and over-ride such 'structuring'.

Personally I don't think PNF had a clue what the a/c was doing. I also wonder about the interpretation of the CVR where he says " you are climbing, go down" - did he meant that but had not seen the altimeter going up to oblivion or did he actually mean "your nose is pointing up, put it down"? Until very late there seemed to be no recognition that despite the nose being in 'Climb' mode, the a/c was actually in 'Descent' mode. It appears, unbelievably, that these two, and make that three eventually, believed that a high nose attitude was all you needed to go up.

No, but you keep on talking about unloading, maneuvering with respect to Gs and all the other neat stuff that works very well on high power, high drag machines with low aspect ratio swept wings that are used to bomb the :mad: out of the opponent or shoot down his aeroplanes. While some of it are applicable on high power loading, cruise efficient and not very maneuverable machines we use to transport passengers from, A to B, training airline pilots in them would be utterly superfluous as there are already proven and taught procedures to deal with just the stuff that was thrown onto AF447 crew. They did nothing resembling them.

Aeroplane was stalled by then. There are significant differences in flying qualities between stalled and unstalled aeroplane.

FBW Airbi are flightpath stable in any altn law so the effect of the changing thrust on pitch is automatically canceled and at the computed airspeed at the time stall warning went off the second time, flight controls authority would be pretty sufficient, especially as the difference between TOGA and cruise power at altitude is minimal. Powervise, there is a world of difference between same N1 at cruising level and at sea level - and concomitant pitch moment.

Graph shows right stick to be most of the time in the nose up area, confirming BEAs finding that aeroplane behaved as commanded.

So "run out of speed" shouldn't be misread as: "...and then stalled" but as "...and then got so slow to activate stall warning that made CM2 pull and consequently stall the aeroplane." I apologize for misunderstanding your post.

Your interpretation. Incongruent with busting the level by couple of thousand feet subsequently.

I have already posted that successful succumbing to somatogravic illusion requires higher levels of acceleration - such as a TOGA kick. That's what made Air Transat crew succumb to it, not average acceleration. Popping the speedbrakes on the very fast jet might lead to similar Nx values in deceleration sense but I think we have already established that such an equipment was not used on the AF447 route. Now it is possible that mere deceleration of climb can make the pilot succumb to somatogravic illusion and perpetuate the climb into the stall but anyone proving it will open a whole new chapter of aeromedicine.

Suddenly realizing that instruments are not infallible and losing all faith in all of them? Any rational thought abandoning them for good? What difference does it make if they succumbed to this or that illusion anyway?

...yet the average was nose up.

IBEAHO:

There is a picture that goes with it. Also one on the page 97 of the French report (fig 64) - very ugly stuff.


Probably we wouldn't be discussing AF447 at all if it were the only thing they didn't appreciate.

...in military. Civvies have it mostly as pitching down in go-arounds as the low drag, cruise optimized designs just can't produce enough deceleration for it to be really dangerous.

Sorry that i wrongly assumed, that changing g loading, thus reducing or increasing AOA and thus changing flightpath is understood by civvies and also by yourself. Finally it i nothing less and nothing more than a result orientated change pf pitch and has nothing at all to do with the military, although the used terminology is more present there.

For you and the others who didn´t understand:
unload = reduce g= normal acceleration from present value to a lower desired value, usually performed by a nose down flight control input, using the available pitch steering device (Stick, sidestick yoke, trim....).

You agree, that it can be done also by all aircraft with wings on it and would have been the necessary means to keep AF447 within the flight envelope and prevent the stall, when properly performed?

Unloading would save the AF447 but it is far from being only possible solution. Other ones: not pulling in the first place, not disregarding the stall warning, returning to assigned altitude instead of merely reducing the RoC from humongous to merely excessive, etc...

Unloading is the most effective on highly aerobatic, very powerful and draggy designs, such as Su-26 or Su-27.

Hello again everybody
Can anyone tell my why after the official report there are 35 pages of debate about what is a fairly clear sequence of events and set of causes? I have no inclination to read these thirty five pages but really gentlemen and ladies the cause is known. We can speculate about the motivations behind the cause but these lie in the area of psychology not technology.

... not counting 74 pages in thread no. 9 ...

I have, but as you was, in a way, questioning his opinion, my reply was to support or justify his opinion.

Not pulling in the first place would have prevented the the whole event, as would have functioning pitot tubes. It is self explanatory.

Returning to the assigned altitude, there starts the problem, if you refer it to the part after initial pullup. This returniung to the altitude was imho exactly what the PF tried, smooth and easy and no coffee cups on the floor and no passenger complaint. But he f**d up badly in the pullup and a normal return to the assigned altitude like in day to day flying with easy initiation and all doing nicely worked not out as planned. The speed decayed unobserved due to failed pitots and unnoticed due to lack of common sense concerning aerodynamics and energy management near the service ceiling of the aircraft. The necessary recovery action was time critical.
In this situation returning to the assigned altitude has to observe those specifics and the primary focus has to be angle of attack reduction and speed conservation. The normal parameters for changing altitude or regaining altitude like a special pitch change, a special change of vertical speed, a known SS input might not work in the time available.

I referenced the amount of change to the normal load factor value, as that one is documented in the FDR. I´m well aware that afaik neither AOA nor normal loadfactor are readily displayed in the cockpit.

Unloading can be performed in any aircraft and is done during any approach to stall recovery. On which aircraft it is most effective is of no relevance to the discussion here.

My post has nothing to do with a special maneuver, what i´m saying is that an early recovery atempt before SW2 was made, documented by the normal load factor in the FDR, computed by HN to be +.87 in the average, but that it was not agressive enough.

It would have been sufficient, had it not been terminated too early. Why the PF reverted to pulling the nose up remains the biggest mystery of all for me. The report mentions the return of the flight director, the fixation on overspeed, training exercises at low altitude ...

P.S. What strikes me in the various 'level bust' incidents, and in the pitchdown of QF72, that pilots react instantly to an overspeed situation, but are remarkably relaxed when the airplane climbs 3000 ft towards its stall ceiling.

I know you have. What's your source of information, or is it something you just make up?

Please see slide 24 of Operator s Guide to Human Factors in Aviation or somatogravic%20illusion.ppt

According to my maths, accelerating from 170 to 200 kts over 10 seconds is about 3 kts/sec.
The graph of AF 447's ground speed shows a deceleration rate of about 3 kts/second during the climb from FL350 to FL 380

If an acceleration can produce a sensation of 9 degs nose up, why can't a similar deceleration produce a sensation of 9 degs nose down?

See Operators Guide to Human Factors in Aviation.

The difference is it may explain why two qualified pilots made those errors that night.

Taking its definition literally, a pilot is under somatogravic illusion anytime he is flying on instruments but believing his bodily sensors rather than his instruments. Since that is contrary to basic instrument flying training, there must be some extraordinary combination of circumstances for this to happen. Is a deceleration of 3 kts/sec sufficient explanation by itself, for two qualified pilots at the same time?

It can, but when it is caused by the attitude being actually 9 degrees nose up, the sensation would be that of level attitude.

I have repeatedly warned against trying to build advanced theories while having no firm grasp on the basics. It was a win-win proposal for me.

Folks listen to me, bandwidth wastage gets reduced.

Folks disregard, I'm kept entertained.

For those unable to take subtle hints: anyone proving somatogravic illusion played a role in AF447, or for that matter that the illusion of pitch down due to deceleration in any airliner incident/accident, would make such a breakthrough that he would stand a good chance of winning both Collier trophy and Nobel for medicine. Good luck with it and don't try to do it with G-CPAT incident, it was pitch-up illusion. Basic aerodynamics folks. Lift to drag. Trust to weight.

Oh and thank you for providing very interesting link, rudderudderrat - the one with very vague and general description of somatogravic illusion during takeoff and landing. Applying lessons "learned" from it to instance of UAS in cruise would have been heavy work, leaning heavily on imagination. Anyway:

...cracked me up. Maybe if one is flying Dauntless and opens split flaps in one go. Airliner flaps are a) not so draggy b) never lowered full in one step. Makes me wonder at what operator
was that presentation aimed.

It has to do something with human factors. I mean regarding to posters, not the crew.

First, that's not the way it works in the real life because a) pilots are trained to put safety before comfort b) other similar incidents have shown a) is observed in real life for most of the time by most of the crews. Second, CM2 warned FAs about possible turbulence ahead four minutes before UAS, therefore chances of coffee being a factor were nil. Third, calling sidestick movements recorded on FDR smooth and easy is not something I'd do but then it could be my level 2 English.

True, but it was not even initiated.

In F-4 Phantom. Is it so hard to accept that airline pilots are not trained in ACM so their procedures, while still working as supposed, are not leaning heavily on maneuvering part? Even if they went to Climb thrust/5° pitch at the apex of their climb, aeroplane would stabilize at alpha slightly above 5° and perform gentle driftdown to 5° alpha ceiling.

It is not as important to know the reason and principles involved in procedures as it is important to perform the procedure timely and precisely when required. Now, I'm not saying that detailed knowledge of aeroplane, HF and air is useless, just that many a pilot had successful and long flying carrier while being oblivious to some basic flying facts.

Here we go again:

Pushing the stick full forward on Airbus gives you -1G clean (and fast enough, about which there was no doubt when second stall warning went off). That's enough enough. Now watch the ignorant bite on this one.

Because they are absolutely inessential in transporter! We might install them one day when we go seriously about the business of air combat in A330 but I can't see it happening anytime soon.

No, but is as convenient to derail discussion as is composite fin of AA587, NDB identifier regarding the AA965, core lock of Pinnacle 3701, or who-knows-what-not at Habsheim. Same stuff on anonymous internet fora every time Caucasian (minus Russians) crew stuffs it up. Lesson from worldwide spread of accidents is there are no American/Chinese/Russian/Somali/Graustarkian aerodynamics or physics and flying does not care a little bit about pilots' cultural background, it's just some cultures are more prone to rejecting the traditional and embracing the pragmatic - essential for aviation. Instead of understanding it, what we have on the PPRuNe is a lot folks mistakenly believing that they know something about aviation and gloat about how their cultural circle has better "safety statistics" than some other one. So then comes AF447 and dreams of immanent aeronautical superiority are shattered and we get thread upon thread of nonsense coming from those wounded by their Aeroweltanschauung suddenly shown to be false.

Answer "a la clandestino" (fair enough)
Anyone proving somotogravic illusion not played a role in AF447 would make such a breakthrough that he would stand a good chance of winning both Collier trophy and Nobel for medicine

clandestino
It is certain (for clandestino at least) that AOA is truly one of the less important data
However when this data is outside that prescribed for the airplane ..this airplane become an iron mainly subject to the Newton law ....

Sorry - missed this.

I'm pretty sure I stated my opinion the first time CONF iture posted that video, which if I recall correctly was along the lines of - he's as welcome to his opinion as anyone, and his feat of flying certainly means that opinion will have clout and I for one am in awe of what he pulled off. Nevertheless, I disagree with aspects of it on the grounds that there have been several instances of pulling into stall (at least one of which involved UAS) where the presence of a linked PFC had no effect on the outcome.

You may well ask who the hell I am to hold such an opinion, and the answer is "nobody". But the fact is that the argument stating linked controls will prevent a situation where one pilot pulls back into a stall and the other does nothing is demonstrably untrue.

Your bandwith of self esteem will remain unchallenged.


New message there, pilots always do what they are trained for? Are they trained to crash too like AF447?

That s not what i do and nothing i said. , but what the PF intended to do and was not able to because of lack of manual flying expierience in FL 350 in ALT2B law.


Then you have an different explanation for the reduction of V/S, Nz , for the SS being ND until 3 sec. before SW 2 ?

You are entiteled to contact BEA and tell them your point of view, especially the misuse of the unreliable airspeed procedure which would have worked well after AP-disconnect, as an high altitude approach to stall recovery procedure. Good luck with it.

As you make yourself an expert in ACM, please note, that -1g (full ND SS) produces nearly the same drag as +2g and would be not suitable to regain energy.

:ok: Well that's the point! The crew was trained to recognize and deal with UAS, they didn't follow the training. Now that in itself is a moot issue as before any abnormals aeroplane has to be under positive and proper control, which it turned out not to be. AF machines suffered from UAS before, it was the first and only that crashed.

For umpteenth time: this is severe misinterpretation of the report. If aeroplane's attitude was gyrating around some acceptable value, then one would be justified to say that pilot had a problem with manual skils. Both attitude variation and stick positions confirm that CM2 was bent on climbing the aeroplane without understanding the consequence of it and without verbalizing what are his intentions or perception of the situation and that goes against basic airline pilot training anywhere.

Simple. Airbus 330 is not F-4. Proper recovery action is not unloading but achieving stable attitude and power and then recovering the altitude (if affected at all). CM2 never achieved anything like it. He made a half-hearted attempt to reduce climb but even before he achieved anything like useful pitch, he reversed into pulling again into insane attitude for the altitude they were flying at. Insane for A330, not F-4, that is.

I wasn't discussing stall recovery at all, just UAS. Is there any doubt that stall was brought on by CM2's completely inappropriate reaction? Well, I did warn about need to understand the matter discussed to have meaningful debate.

Airbus 330 is not F-4. It is very low drag, low maneuverable and low powered, compared to Phantom. I referred to fact that means of complying with UAS procedure were readily available. I have already mentioned that a pilot can have a very successful career just by doing as trained and as written in manuals without having a grasp on the basics.

Loss of energy during climb in airliner is not the same as the loss of energy during maneuvering a fighter and same procedures need not be applicable.

Anyway, figure 64 of the French report shows the calculated trajectory of the aeroplane without any crew input, demonstrating that even doing absolutely nothing would lead to much better outcome than what the crew did.

As for investigating authorities, they make recommendations, based on the accident/incident they investigated and are not required to estimate the overall impact of them. That's something for manufacturers and aviation authorities to do (and is reason enough to keep investigating bodies independent). Their response might be acceptance, reject or anything in-between and gets classified by investigators as acceptable or unacceptable. Now, installing the AoA gauge seems to be the way to go to BEA but then EASA might point out that a) other crews reduced AoA in UAS situation when stall warning went off b) thousand upon thousands of civil aeroplanes are flown successfully every day without AoA gauge so the reccomendation is rejected. It is possible that compromise solution will be found with visual stall warning. It is possible recommendation will be accepted, we'll get gauges and new training procedures grafted onto existing ones. We shall see what we shall see.

It's interesting 'hearing' a fighter guy talk about airliners and an airline guy talk about fighters (and I mean that in a complimentary way to both).

When going from a 727 flight in the morning, across town to an F-16 flight in the afternoon, I occasionally had the feeling that I should stop off at a phone-booth and change from Clark Kent to you know who. :)

In absolute terms, they are indeed different worlds, but aviation best practices span them both. :ok:

Quit the F4-Thing. I was qquoting BEA (for your convienience again below.

That seems to be a permanent problem, that you take out of a discussion what you like and make a comment that suits you. We, or at least that was the beginning of my involvement again, were discussing the time after the initial pitchup until SW2. After the AP disengagement until the initial pullup the UAS procedure would have been appropriate. After the initial pullup we talk per definition about an upset situation. The upset started per Definition with SW1 and lasted until the end of the flight.


There are those pilots, who had a bad day and lived through it, those who still have that day in front of them, those who never will expierience a bad day, and few who perished like AF447 did. I prefer those pilots, who have the knowledge to handle such a bad day by using knowledge and expierience.

By mistake or by what intention? To counter the deviation from assigned altitude, to correct the pitch, to arrest the climb? Or did he do it unintentionally, by chance, or because he forgot that he liked pulling?
It was half hearted or not enough, whatever you call it, and that is exactly what i said and what you needed to comment on with:
OK, we agree, that you must be in disagreement, whatever another post says.

Again you draw the comparison on a fighter aircraft and you dont have any idea of it. Hitting stall warning with 5 g´s (with 1,6 g´s a fighter is not maneuvering but merely easy turning)) on an fighter during maneuvering is no big deal, relax the g´s and that´s it.

But loss of inapropriate amount of energy or better like in this case the exchange from kinetic energy (speed) into potential energy (altitude) causes the same problems in all aircraft, if the altitude exceeds the service ceiling of the aircraft for the given GW and the given flight circumstances.

We can agree, that we agree on that one.

Clandestino concerning AO
We shall see what we shall see

As they are already available (customer option, BUSS) and needn´t being newly developped, and as there is no known difficult training at the moment for those who bought that option i´d say:

We will see it in the coming aircraft, and some although not all aircraft will be retrofitted.

First, thank you Sir.

If you allow me to give your post a personal touch from my POV, than it would look like that: (bolding my insertions)

It's interesting 'hearing' a old but not bold fighter guy talk about airliners and an bold airline guy talk about fighters.

Thank you guys for the audience, it is time to go back lurking and spending my pension.

That is entire two seconds. I didn't mean to imply UAS needed to be done after the zoom climb, just that it wouldn't hurt going to memory items even above the practical ceiling. Too keep the aeroplane within the envelope, resorting to UAS procedure is not compulsory but it helps.

Depends on how "unintentional" is understood. CM2 certainly did not intend to stall the aeroplane but it was his actions that stalled her. Pinnacle 3701, Colgan 3407, West Carribean 708, Northwest Orient 6231 and Birgenair 301 were pretty similar in that respect. If pilot doesn't realize his actions are pushing the aeroplane towards the stall, his chances of initiating recovery are nil.

Alternate law is still flightpath stable, to reduce pitch one must positively push - that's what fig 27 shows happened. CVR shows that CM2 first suggested it would be good idea to go down, CM1 agreed and prompted him to go down but as the warning fired second time, CM2 changed his mind and pulled again (fig 28). Why? No sensible comment was recorded on CVR.

BUSS is, strictly speaking, not an AoA gauge but I agree it might turn out to be satisfactory compromise regarding the BEA's recommendation.

As discussed earlier, the BUSS is no solution for the conditions encountered by AF447. If installed, it can only be made available by switching off the three ADR's, which then remain unavailable for the remainder of the flight. Furthermore, it presents misleading information at altitudes higher than about FL250 because it uses a default stall warning threshold value that does not change with Mach, and (as I understand it) the high speed limit is Vmo but Mmo is not taken into account.

Slide 27: Dr Hamish G. MacDougal & Dr Steven Moore.
Dr Hamish G. MacDougall BSc (Hons), PhD

See Conference Presentations / Peer Reviewed Papers
e.g. 107 "How the Brain Interprets Linear Acceleration During Flight." etc,
Priceless!

Clandestino, you don't need to be ACM trained to understand, and apply (or be wary of) unloading aerodynamic surfaces, or an aircraft.

Please look up "mast bumping" as it concerns a Huey helicopter. I hope you will be able to reconcile the fact that my instructors, some 30 years ago, were able to convey successfully to me the necessity to NOT unload the head, with no reference whatsoever to EVM or ACM. Also the point of keeping the head loaded while doing NoE maneuvers in low level flying.

In simple, Level 2 English, Unloading the aircraft is done by reducing the G load, and loading the aircraft, as you can imagine, is normally achieved by increasing the G load. This is as true in a Cessna 172 as in a Pitts Special as in a Gulfstream as in Mistubishi Zero, or in a Huey or a Lynx.

For Old Carthusian: I believe Clandestino nailed the reason for the added pages: human factors. :ok:

Somatogravic illusion ?
 

The TSB's Finding that the Transat captain PF experienced somatogravic illusion is somewhat questionable. In 1.11.4 Somatogravic Illusion, they write:
That is o.k., but doesn't describe what happened in the incident. The airplane attitude started to decrease at about 1440:32 EST, when the airspeed was actually decreasing. At about 1440:44 EST the airplane started to descend. Between about 1440:41 and 1440:48 the airspeed increased by about 33 kt IAS, 30 kt TAS in 7.3 seconds, an acceleration of 0.21 g. Yet their figure 10 shows a perceived attitude that is 35° greater than the real attitude, i.e. corresponding to an acceleration of 0.57 g. Difficult to understand.
http://i.imgur.com/QhPf5.gif

Hi HN39,

I agree it doesn't match very well. Some of the graphs seem to have slipped by almost 5 seconds.

If we assume the graphs have not been superimposed correctly, and that the greatest illusion of pitch was caused during the fastest acceleration, then between 19:40:42 and 19:40:47 the speed increased from 200 to 240kts. i.e. 40 kts in 5 secs or 8kts per second (0.41g)
ArcTAN 0.41/1 = about +22 degs GIA

When the real pitch and perceived pitch matched at 13 degs (shown as 5 seconds before the start of the acceleration), then the Somatogravic illusion of + 22 degs would make the perceived attitude as 35 degs.

Hi rudderrudderrat,

The report states:
Appendix 1 states:

Time ......... IAS ..... pitch

19:40:40.9 ... 197.5 ... 8.5
19:40:44.1 ... 208.9 ... -2.3
19:40:48.3 ... 230.3 ... -2
19:40:52.1 ... 241.9 ... -0.06

Hi HN39,

I've been trying for ages to get the words and the picture to say the same, but the closest I've come is +22 degs with the accelerations shown.

Hi rudderrudderrat,

You may have noted that my purple line shows the perceived attitude according to Appendix 1.

EDIT::
But you don't question their opinion about the rôle of somatogravic illusion in this incident?

Hi HN39,
The effect is very well documented, e.g. see http://www.faa.gov/library/manuals/a...apter%2001.pdf Page 1-6.

The Incident Investigators concluded the crew suffered somatogravic illusion. The crew survived and explained their reason's for their actions. I simply can't verify the same value, so why would I question their opinion?

This is part of the reason why one is taught a thing called instrument flying.

from the peanut gallery
 

Good flamefest, but I liked Okie's observation and the input from our rotorhead Wolf.

Seems to this old and not so bold fighter type that 99% of everything ever capable of sustaining flight obeys the same rules, gliders included.

- It's damned hard to stay in a stall at zero gee.
- Zero gee reduces induced drag and allows your thrust to have an effect on your speed.
- Forget all the somatogravic illusion crapola. We were all trained and routinely flew IFR when our inner ear sensors and butt told us we were inverted or in a left turn or..... I would submit to this august body of experts that the fighter types had to overcome the physiological stuff more frequently than most of the heavy pilots.
- Jiminy Cricket can suggest that you lower the nose, but the other guy has to do so and not continue an unreasonable stick input. So crew coordination and a clear chain of command comes into play, ya think?

WRT to Okie's observation: I was priveleged to check out dozens of USAF Reserve and Guard pilots that had a day job flying heavies. Think Vipers and Sluf's. I had zero problems when they came outta that telephone booth wearing their cape and then we briefed and flew an ACM or ground attack mission. I always thot that they would be the ones I wanted to fly with seated back in row 26B when something bad happened. So salute to them.

WRT to Wolf's observation: Yep, those rotors are simply moving wings and behave just like the ones that don't move. Only biggie is unloading those suckers unless you were in one of those "rigid rotor" types we tested years ago.

Back to the peanut gallery...

More about somatogravic illusion
 

In post #710 I ok'd following quote from a TSB incident report:
Thinking about it further, I felt I ought to correct that in the interest of an understanding of the flight mechanical aspects of the phenomenon.

Actually only the first sentence is entirely correct. The second sentence is sensorially correct during acceleration on the runway, although it is perhaps somewhat unlikely that it would cause a strong sensation of climbing in an experienced pilot. However, when the aircraft nose is raised in flight, the airplane will actually start climbing and the acceleration will reduce. The reduction of acceleration tilts the perceived attitude forward by the same amount as the real pitch change is nose-up. In other words, the somatogravic illusion is then that the pitch attitude has not changed. A similar argument applies in reverse when the nose is pitched down.

Hi HazelNuts39

Quote..."The reduction of acceleration tilts the perceived attitude forward by the same amount as the real pitch change is nose-up. In other words, the somatogravic illusion is then that the pitch attitude HAS NOT CHANGED. A similar argument applies in reverse when the nose is pitched down."

caps mine......

Certainly that works as an explanation for a pilot to continue his NU input even though he is climbing, and decelerating? pilot has also foregone scan and has lost his binky, the Flight Director, so.......

Too easy?

Yes, a pilot knows that he cannot trust his senses to determine attitude, and must use his attitude indicator instead.