PersonFromPorlock,

Having flown more than 250 hours with NVG's in high performance military jets, I can assure you that NVG's are not part of the solution in this case. Below i will try to explain why:

NVG's are the single biggest killer in the fast jet business right now. This is due to two main reasons. Firstly, while wearing NVG's the pilot will lose all depth perception cues. This is not an issue for a civilian airliner on an IFR route, but for military aircraft flying all sort of tactical formations, it has led to many midairs and close calls. Secondly and more importantly, NVG's tend to lead to Spatial Disorientation among fast jet crews. Maneuvering violently on NVG's in a situation where the horizon is not constantly visible (steep dive) has led to many Spatial D attributed losses.

It takes me roughly 15 seconds to done my NVG's. But that is only possible because I am already wearing a helmet with a proper mount. Before each mission the NVG's are mounted on the helmet/head in the life support room and calibrated. This is necessary if one is to have the best possible result of wearing them.

The keys to succes in the use of NVG's are as follows. Always maintain the horizon in your crosscheck and always include a proper scan of your ADI. But the horizon is not always visible. For NVG's to work properly while used in aviation, the amount of light outside the cockpit has to be above 2,2 millilux. Or you could be in IMC conditions. Wearing NVG's in IMC conditions might also lead to Spatial D.

Then there is also the fact, that NVG's won't work properly if the cockpit lighting is NVG hostile. In military aircraft that use NVG's, there are normally to sets of cockpit lightings. One which is the normal white light, and one which is greenish and kan be selected on when flying on NVG's. The glow from non NVG compatible light will make the NVG's gain down on their own, thereby giving you a pure view outside the cockpit. The NVG hostile light also tends to be reflected in the canopy or windscreens which causes pure visibility.

Last but not least, the one thing that every military fast jet pilot learns when flying with NVG's, is to always be ready to focus on the ADI in case a Spatial D situation arises, since the NVG's will make the situation much worse.

Therefore as you can see, I find it hardly unlikely that a civilian pilot, with no training, in an aircraft with NVG hostile light, possibly in IMC conditions, and with only 90 seconds to live, will get any benefits from spending 15 seconds donning his NVG's, while he could have used the time better looking on his PFD's/ADI's (or what ever they are called) trying to determine which one is lying and which way is up.

F-16Guy,
A question if you please. Not having had the 'pleasure' of flying with NVG since they were just in their infancy when I was in a tactical role, what is this Special Disorientation? Is it due to latency (delay) in generating the view?

I think he means SPATIAL disorientation. A quick google gave this hit near the top.
Rotor & Wing Magazine :: The Dangers of Spatial Disorientation???

Sorry I meant Spatial Disorientation. English is not my native language.....

The link provided by Mad (Flt) Scientist explains it quite well.

There is no delay in the NVG's we use, and they are definitely not a "pleasure" to fly with in the long run since they are quite heavy. The entire CG of the helmet is moved forward when they are donned, and on long missions (3-4 hours), ones nose takes all the added weight.

Mad (Flt) Scientist and F16GUY:ok:
I've been spatially disoriented without using NVG.
We found out later that some anti-malarial drugs could cause it. No fun on a black a** night over the water.

Somatogravic illusion may have been at play here.

AP disconnects due to IRS failure; this failure generates ambiguous nose up display on P1 PFD. P1 pushes ND in response and aircraft accelerates. Both pilots now have sense of increasing pitch up. P1 pushes more as PFD is still showing pitch up. P2 'feels' pitch up but sees nose down on PFD but doesn't comment as they have the PFD miscompare - he may believe his in error. Only when they bring in the performance instruments do they realise something is wrong but as has been mentioned, the aircraft is now very poorly placed.

Pure conjecture, but dark nights with no visual references have caused aircraft to crash due to pilot disorientation even with perfectly serviceable instruments.

NO, thats not the chime. The chime to look for would be right before the Captain said "what?"
The EFIS Comparator constantly monitors both sides and looks for disparities between the two. The chime would be the very first indication of an anomaly in the AHRS/IRU. The caution chime is followed by a flashing yellow push-to-cancel caution light on the glareshield and a red HDG/ATT flag on the primary flight display, with an associated EFIS COMP MON and possibly AHRS/IRU1 or 2 displayed on the EICAS.

It's already there, called the standby attitude indicator. The standby is a totally independent third system right in the middle of the cockpit. Some are a very nice digital ISI, others on the older A/C would be the steam gauge type.

Is this a comparison between the PFD displays or is it between the right and left attitude sources? Logically it should be the attitude sources, and if both PFDs are set to the same source for some reason, the warning chime may sound, but it might be lost in the confusion over what just happened.

Unless the accident investigation team finds an external source of data (such as radar glints on a primary radar) that gives them at least a few hard roll attitude data points, they will be just as lost as the accident aircrew was on what the actual roll attitude was.

Without discovering a valid source of attitude information, the probability of the crew recovering from their initial departure was nil. Is it really necessary to know the twists and turns of this aircraft on the way down to learn the necessary lessons from this accident?

Read the Perpignan accident report to see, that exactly such automatic systems can make aircraft crash, if the only correct value is not displayed, because there are two wrong ones available...

7-cylinder man,

I agree that it really isn't difficult, but only if you get to practice it once in a while. And since it isn't practiced much today, along with basic manual flying skills, those skills are lost.

Failure / degradation of the main attitude reference system naturally enough places higher emphasis on the standby instrument, normally an electrically driven gyro.
On all of the types I have encountered in commercial ops, this instrument rather small and positioned center left on the panel. Sure we have all practiced with it in the sim, normally as a stopgap to bring the main systems back online, but of course, when it is really needed on the proverbial dark and stormy night, it CAN get lost in all of the much brighter and noisier failure modes, and from the ones that I have used, once the aircraft is in a very bad place, it is not a great tool for recovery simply by virtue of its size.

Just thinking aloud, but perhaps something as simple as a ring of LED around this instrument that illuminates at a mis-compare signal (and training of course) might help in getting the attention to where it should be when things go pear.

The source select is a small rotary knob that take a firm grasp and rotation of 45 degrees from the normal position.
When using other than your primary source an amber ATT/HDG 1 or 2 is displayed across your PFD. It would have to be done intentionally and directed by the QRH handbook. That will have to be left to the investigators to determine.

The normal mode of operation is independent attitude sources for each pilot. the only good reason to both be on the same source is if one is already identified as failed. in which case (1) it's made very clear that you are doing so (and cross-check with the standby would be even more important than normal) and (2) would you want the system nagging you the rest of the flight about a miscompare with an identified failed unit that you've already addressed.

There are good reasons to base the comparison monitoring on the displayed data.

It was sometime in the 1970s, around 1976 I think, that there was the crash of an HS-125 near Washington-Dulles Airport, Chantilly, Virginia, when the cause was determined to be the failure of one of the two attitude indicators. Then the pilot flying chose to follow the failed indicator, when I think that the aircraft came apart in flight.

That accident was followed by the requirement that a third attitude indicator be fitted, so that the crew can compare all three, to find that two agree. This is the reason that the standby attitude indicator is referred to as the "tie-breaker," when it is assumed that it shall indicate correctly to agree with the one of the two other systems that is also indicating correctly.

Would a failed IRU be something that might be dispatched under MEL guidelines? If so, there should be a record. If something happened inflight to fail one IRU significantly before the loss of control, there should be a record on the CVR. It would be highly improbable to have a second IRU failure in close time proximity, unless there was some sort of common failure mode and with the IRU units being located close to each other (eg. an electrical fire, an environmental control failure or ??)

I've had a few attitude gyro failures in my lifetime and it has been an easy matter to find the indicator that still follows the control motions, but that probably assumes you have not already grossly upset the applecart.

The Captain knew he had problems, but why oh why did he just cry "help me, help me?" He should have known where to find good information and latched onto it. I suspect a panic reaction shut down his reasoning processes, Panic generally results from inadequate training-not knowing instinctively what to do next.

If the Pilot Monitoring was doing his job and had good attitude information in front of him, he should have taken over control and stabilized the situation when the aircraft departed its assigned altitude and particularly when the PF began to ask for help. Either PM was just along for the ride and didn't believe or understand his instruments, had bad information in front of him, or was looking at other things trying to understand what core problem was.

Like AF447, the crew in this accident seemed to have very weak altitude awareness. I suspect that the design of many PFD displays hampers altitude awareness under distracting and dynamic conditions.

For you folks who are currently flying the line, I have a question. Wouldn't you as pilot monitoring know if the other guy/gal is 'losing the bubble' and beginning to lose control? Otherwise, what are you monitoring?

It would be interesting to learn whether this IRU had issues before, just like the RTLU for QZ8501...

Looks like they got very odd pitch indication, and then tried to correct it by manoeuvring the aircraft.

Maybe the Captains PFD suddenly showed them they were climbing, so he pushed the nose over in an attempt to 'level' the aircraft?
Maybe they also were seeing an erroneous bank angle, which they also attempted to 'correct'?

It's so easy to chuck a comment in, but apart from asking why they didn't revert to the standbys, I think most folk would ask 'why do anything, straightaway?'.

If the aircraft was in straight and level flight, and some wonkiness appears on the flight instruments, I'd probably have held the controls where they were, and started looking around for the source of the trouble....bit like unreliable airspeed.

The other thing is, once things were clearly going pear shaped, does neither of them look at the altimeter?

Poor guys.:(

7-cylinder man,

In the perfect world that would be truth, but many resent events in the civilian aviation community have shown that training of basic ”pilot ****” is a thing of the past. Here I especially have incidents like Colgan Air 3407, Air France 447 and Air Asia 8501 in mind.

While I know that there are many professional and talented pilots in the civilian world, I also suspect that the ”Race to the Bottom”, created by the influence of low cost carriers world wide, have created room in the cockpits of commercial liners, for pilots that have less than 250 hours total time on machines that needs to be hand flown. And once those pilots get into the RH seat in a larger machine, the amount of ”stick time” that they will get is ridiculously small. They will never really learn to feel and fly their aircraft.

Now put a pilot like that in a Partial Panel situation where he has to hand fly his machine back to a safe landing, and best case it will be ugly but he will live, and worst case he will crash his aircraft within 60 seconds.

Many companies have been very reluctant to allow pilots to hone their skills in the air when conditions permits, because it affects passenger comfort and it costs a bit of extra fuel. Then they say that pilots can practice their hand flying skills once a year in the simulator. Get real!

I am so fortunate to work for a “company” that does not get affected by the publics demand for cheap tickets. Therefore we have the luxury of writing all our SOP’s and regulation with one thing as the main focus point. Safety!

Beside of the fact that most of the flying is "hands on", I get one ride in the simulator every 3 months where emergency procedures are practiced, as well as recovery from loss of control. Furthermore I get one instrument check ride in the simulator once a year, where Partial Panel and no giro emergencies have to be demonstrated. Why is that? Because when the **** hits the fan, the only thing that matters is proficiency. It does not matter if you get the most sophisticated presentation of your checklist on your screens or if you know all the systems by hart. If you are not able to fly the aircraft first with basic stick (yoke), rudder and throttle inputs, everything else does not matter.

In my “company” you are considered experienced when you have 1000 hours on type. Every time I read a safety report from the civilian world where it states that the both pilots where highly experienced and had several thousands hours on type, I cant help but thinking, I wonder how many hours of hand flying the type they got? Would they be able to hand fly their aircraft take-off to landing in IMC conditions even without some kind of failure? In my mind they should not be let loose in an aircraft if they 100% positively can.

Back to this incident in Sweden. We still miss a lot of information, but the SHK (Swedish Investigating Board) will in time tell us what went wrong and why the pilots where unable to correct the situation. One thing that I think is important to remember, is that if the accident was a result of poor pilot flying skills, the company and the regulators have a huge responsibility to make sure pilots get the necessary training.

What worries me in this case was the lack of communication. There was no "wow my indicator is showing pitch down" - "Oh mine is showing pitch up"
Had the PF been following a duff indication, and the PM's display being good, that would have triggered further though and a glance at the standby indicator.
It seems to be the case in many accidents that the 2 pilots just aren't talking. (AF447 et al).

Good post F-16

I am wondering if the Capt spilt his drink all over the centre console? This would account for the expletives from both - I can just imagine that happening. Then, the liquid started to cause short circuits and failures in the equipment as it dripped down. I don't know the physical avionics layout of the CRJ, but this is a possibility. The liquid could also have caused an IRU failure and/or the PFD source to switch so that both were on the same IRU. Faced with a rapid series of aircraft failures and cautions, and with hot coffee all over his trousers might explain why the Captain did not make a sensible reaction. (Although, the command 'you have control' might have helped).

Yes, that is all well and good, but after average duty periods these days (i.e., long) and with today's average pilot rosters, folk are not going to be studying the FCOM on their phones in their precious time off.

In my experience, there is rarely spare time in the SIM, and even if there is, the other two want to bugger off so one feels one cannot ask for them to stay so you can practise something or look at a scenario.

Modern automatic aircraft are so complex that crews rarely get to experience all of the failure modes in the SIM. Even if they did experience all failures during initial training does not mean that they will have perfect recall of it and the appropriate actions on a dark and stormy night many years later.

In my opinion, not enough time is spent in recurrent SIMs practising unusual attitude recovery and instrument failures or unusual indications. Were this to be done, who knows, perhaps this crew and AF447's and many others would still be alive?

Yet some people jump with findings and conclusions, as pilot error and poor CRM. We have no clue what happened and we are very far to know why.
Better try to figure out what possible happened. As example, I think they did a good job by keeping the wings at horizontal. The aircraft flight path wasn't a spiral (as per radar data). Moreover, the available FDR data after 23:20:10 shows that the roll indication was really wrong, they didn't inverted the aircraft. The two reliable data, as ground speed increase and positive gees, +1.5g to +2.5g are incompatible with roll data (aircraft inverted). For some reason they were unable to level up before hitting the ground.
By the way, the pilot is still more sharp than automation, the strong exclamation what(!) came couple of seconds earlier than AP disconnect.

_Phoenix
I can pull lots of g while inverted. To pull out of a dive requires that the g be applied in a consistent direction. If there is any significant roll rate, the time to pull out of a high speed dive ~ 20 seconds at modest g levels, will be much longer than the time to roll 180 degrees. SHK admits that they do not yet understand the roll data.

Machinbird, I was pretty clear:
ground speed increase AND positive gees, +1.5g to +2.5g are incompatible with aircraft inverted.

No, perfectly compatible.
Roll inverted any aircraft then pull.
You will accelerate and pull positive G

Syntax,

Sorry, but the crew WAS experienced. Why is it that people, even professionals still see hours as the ultimate?! It is irrelevant.
It are the amount of sectors flown which is important, and flying Night parcel cargo gives you plenty of sectors, at night, in all kinds of weather, often to smaller airports with less aids.



Your claim regarding the Nationalities of the crew not used to winter ops. Is again something I would expect from a wannabe who is completely wrong.
The crew was flying for the airline for several years,mand guess what, nearly all CRJ flights of West Atlantic are operated within Scandinavia.
Some of the worst Icing can be in Northern Spain by the way, and also France has its Icing issues.

On appearances, you would be correct although an uncorrected roll rate (due to rolling PFD) could still foul up the recovery by turning the velocity vector.

However what is the source of the ground speed data? Is it the IRU or is it GPS? Once the IRU is corrupted, anything that it generates is suspect.

My personal opinion is that as long as the crew was operating from a corrupted attitude reference, the probability of recovery on a black night, possibly under instrument conditions, over sparsely inhabited terrain would be nil.

The altimeter would have told the story that they were being lied to and were out of control. They then needed to find a usable attitude reference such as the standby indicator and use that until level. Once stabilized they could go about selecting an operating IRU to display on the Captains PFD, or failing that, cover over the PFD with a piece of paper to prevent distraction. Any Instrument Rated pilot who cannot operate at a moments notice off the standby indicator is not ready to be flying instruments. You never know when the guy with the bony finger might administer a flight check of your competence.:uhoh:

Machinbird,

Funny you said it, my personal technic is to use one of my flight gloves to cover the affected ADI if its to distracting. However this will only work under positive g's....

Elevator problem?
 

This has probably been mentioned, but I don't have the time to check the whole thread:

According to the FDR traces in #173, the right elevator appears to be acting strangely. There are five or six areas on the trace where it is deflecting when the left elevator isn't and vice versa.

I wonder if there was a flight control problem? I have never flown the CRJ and I don't know its technical arrangement - is each elevator controlled by a different computer? Or perhaps they had a hydraulic system failure which only affected one side?

@uplinker

CRJ primary flight controls are mechanically signalled from cockpit to the PCUs - cables (mainly) and rods and levers - no computers involved. (There are electronics with pretty limited capabilities involved in the command of the Hstab and the spoilerons, bot not elevator, aileron or rudder). Also, both elevators are powered by dual hydraulics, so a single hydraulic would not prevent control on one side. (But see below)

Regarding the trace you comment on. Be very careful looking at left-right differences in FDR data. Often, as is the case here, left and right parameters are recorded asynchronously. The little dots show the actual data points - the lines are merely conjecture by 'joining the dots'. So in cases of rapid movement, the lines can appear to disagree because each is "cutting the corner" between mislaigned data 'dots'. As a result I would tend not to worry about any "spikes" where only one or two data points seem to disagree - you don't actually know what the position of the other elevator is AT THE SAME TIME. Both may be in step with each other for all you know.

There are two places where there seems to be a split between the traces - shortly after the point where the overspeed warning started according to the trace. It is possible that hinge moments on the elevator at high speeds and (relatively) high deflections at that speed slightly limited the elevator one side more than the other. There's no evidence of any hydraulic failure (we ought to have a warning I suspect, which no-one has yet pointed to, either on FDR or CVR) but IF such had occurred and affected a PCU on one side only, MAYBE that might explain HM limiting on one side only. But there can be other causes for that, including small amounts of sideslip, or roll, affecting the forces on each tail differently. Without some direct evidence of a hydraulic failure, I wouldn't conclude one from the elevator trace, personally.

OK, it seems weird - from the point of view of working out what happened - that the traces are not synchronised, but fair enough.

The reason is more or less this: in 99% of cases the two asynchronous parameters are in sync anyway. So by recording them asynchronously I effectively get twice the sample rate for "elevator position". Only in the rare cases where they don't agree (disconnect pulled or mechanical failure, say) does that not apply. In the majority of THOSE cases, it's clear what is going on - for a jam, for example, you'd see one elevator stuck and one still moving. Add in CVR type evidence (which would confirm the disconnect had been pulled, for example) and you can pretty easily resolve any differences.

On older units, asynchronous recording was a way to capture both the required rates and record all the relevant items, since memory capacity was an issue. It's less so today, but old habits die hard.

To elaborate slightly, DFDRs record in "frames" - the 'major' frame is typically 1 second, a major frame is made up of multiple 'minor' frames (the minor frame size depends on the recorder - older recorders were often 250 ms, newer are much faster). Even within a 'minor' frame, the recording is not synchronous - the recorder cycles through hundreds or even thousands of parameters during that minor frame so it's not a snapshot as such.


I've looked at lots of engine data from DFDRs with the parameters normally recorded at once per second (although sometimes slower). You quickly learn that rapidly changing parameters are basically +/- half a second relative to other parameters.

Still nothing on this? Doesn't this seem a bit weird with thousands of the things still flying around?

I think they're waiting for the snow to melt, if it was a failure of the display or instrumentation, how would they determine the cause from those bits and pieces?

Things like switch and knob positions may be available as well as non-volatile memory in some electronic devices. Witness marks will also validate the position of flight control surfaces and other movable components of interest.

TRF4EV3R

SHK has concluded there is something wrong with pitch, roll, heading data. FDR data shows values that would not correspond to the actual movement of the airplane. To further investigate this they need to recover instruments et al from the wreckage to study witness marks or other possible signs (knob positions) of what may have malfunctioned.

Right now the wreckage is frozen into what I would describe as a temporary glacier kind of environment. The snow on the impact point was very solid and melted temporarily when the aircraft struck. It then re-froze and to retrieve items from it would need special equipment. Problem is, this area is so remote there are no roads and the only way in during snow season is by snow mobile or helicopter. Obviously you can not transport heavy machinery on either of these transportation modes so we need to wait until spring when the snow melts. This would possibly mean May or even June, so until then there are few possibilities of recovery of important instruments.

Last thing I read about this was in Norwegian media (nrk.no) the 8th of March.

Any news on this one ? I guess weather should be more amenable these days...

"More amenable" is a relative term.

We are talking about a site in the sub-arctic (Lat 68°N) at 1000m elevation on an inaccessible mountainside, and buried by impact in the snow pack.

Could be August before the snow melts enough to be handled with man/helo-portable equipment. Current Tromsø weather forecast indicates they are expecting rain and clouds most of this week, which may mean the mountain site is "socked in" and not accessible even to helos.

Sounds like work at the site is about to start up again - but not really for the sake of the investigation. Google translate (source):

Kind of macabre, but is this not also possibly to recover the remains of the crew?