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-   -   CRJ down in Sweden (https://www.pprune.org/rumours-news/572882-crj-down-sweden.html)

cappt 13th Mar 2016 22:44


Were there alerts for attitude systems disagree? If so, they seem not to have gotten the crew's attention in time
Yes there are alerts. The alert would be a chime on the CVR.

PersonFromPorlock 14th Mar 2016 01:27

How about equipping crews with night vision goggles, or pilots carrying their own? They aren't that expensive, and being able to see a visible horizon at night once the SHTF might be a life saver.

I don't mean they should be worn routinely at night, just available for quick donning.

F-16GUY 14th Mar 2016 09:25

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.

Machinbird 14th Mar 2016 14:19

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?

Mad (Flt) Scientist 14th Mar 2016 15:32

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

Recognizing spatial disorientation, especially when using night vision goggles (NVGs), is a key skillset that every pilot needs to learn.

F-16GUY 14th Mar 2016 17:32

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.

Machinbird 14th Mar 2016 19:00

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.

MOA 14th Mar 2016 21:40

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.

cappt 14th Mar 2016 22:04


And the CVR did record a chime: it was there, right after the AP disconnect cavalry charge. And there were further chimes throughout the recording. None of the pilots mentioned any EICAS or PFD warnings though. They remained focused (mesmerized) trying to correct aircraft attitude.
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.


So, maybe time to add a third system and use it as a tie-breaker when the two main systems disagree
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.

Machinbird 15th Mar 2016 05:51


The EFIS Comparator constantly monitors both sides and looks for disparities between the two.
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?

Volume 15th Mar 2016 08:17


Now, with three electronic devices, it should be easy to automatically compare all *three* signals - and provide a better hint as to which two are agreeing and which display is inconsistent with the rest.
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...

F-16GUY 15th Mar 2016 08:26


Originally Posted by 7-cylinder man (Post 9311060)
If, before a failure of an IRU, both pilots had been operating using the same source, they would have had clear indication(s) of that.

A basic skill for any pilot is to be able to identify discrepancies between displayed information and to interpret the cause. It really isn't that difficult, but it does often seem to me that it is becoming a lost skill.

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.

Teddy Robinson 15th Mar 2016 09:00

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.

cappt 15th Mar 2016 10:43


If for some reason the FO had also selected the IRU1 source, then there was no chance of any warning being triggered when IRU1 started to go wild - displayed
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.

Mad (Flt) Scientist 15th Mar 2016 12:44

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.

chuks 15th Mar 2016 18:24

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.

Machinbird 16th Mar 2016 03:04

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?

Volume 16th Mar 2016 08:38

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

AtomKraft 16th Mar 2016 09:28

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.:(

F-16GUY 16th Mar 2016 09:54


Originally Posted by 7-cylinder man (Post 9311289)
Unfortunately when the poo hits the fan there will be no one other than the crew to resolve these sort of problems. Is that not what a professional pilot is required to do?

The failures would have been covered in the initial training. As well as the cycle of failures that will form the recurrent training by an ATO there is normally time to practice those little extra items if you ask the trainer.

These days we have the luxury of FCOMs in PFD format that can be read and studied on mobile devices. No excuse not to know the systems and procedures required in doing the job.

Not a dig at you 'F-16 guy'.

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 shit” 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 shit 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.


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