Engineering design Vs Pilots perception

[John Farley]

JR

I wonder if the instrument you saw was switched off and so the pitch drum gyro was not running - that could have explained things

JF

[Double Zero]

One thing which horrified me, when I spent a season in ( clapped out ) Cessna 172's; one day we were trundling, straight and level, when the artificial horizon keeled over.

The senior ( and aerobatic trained ) CPL remarked as if it was nothing, " I see the vacuum's failed " but it struck me as damn dangerous, especially for inexperienced pilots caught out in IFR; am I right in thinking that in something like say, a Hawk, an 'inop' red signal would have come up over the instrument ?

I do know several Sea Harrier pilots were said to have been killed on attempting vertical landing ( source- another Sea Harrier Test Pilot, not J.F. ) when following their artificial horizon at night & the gyro's toppled, leading into a steep bank & crash into the sea.

Mind you, that pilot liked the Harrier, but wouldn't step into any aircraft, light G.A. or Military, unless a lot of £ signs flashed before him.

[Jetstream Rider]

JF - possibly, that did cross my mind, but apparently not according to the person I was with at the time. Will dig around and see if I can find a link to a picture.


Its interesting to note above that flight sim pilots on their computer normally fly the sim seeing their aircraft from behind. Back in my youth I did that with MS flight sim, as I hated not being able to see sideways or have any peripheral vision.

In my experience there is a big difference between sitting in a fixed base sim and a full motion sim. Even if the motion is off in a full motion sim, ones brain is still fooled into thinking it is moving - in fact I was "flying" one with the motion off and the back door open. Looking behind me as the sim did some visual gyroscopics was quite disorientating. However most fixed based sims have poorer visuals, usually just a flat front screen. If this is the case it leads people to fly the screen, not the aeroplane, at least if they have no experience. This does not seem to happen in a full motion, or perhaps I should say full screen sim.

[Jetstream Rider]

Here are a couple of pictures of a Yak 18T cockpit's with a "brown on top" AI, that I mention above.

Photos: Yakovlev Yak-18T Aircraft Pictures | Airliners.net

Photos: Yakovlev Yak-18T Aircraft Pictures | Airliners.net

If the links don't work they are Airliners.net pictures 1454088 and 1250999

I've never flown with one of these, but especially the one that is blue on the bottom, to me seems completely wrong. In IMC in an unusual attitude I'm sure I'd get it wrong. With different basic training however perhaps not.

I'm glad I found the pics as I thought I was dreaming! Definitely not toppled here as in flight.

I had a look at some Mig 29 cockpit shots too and it appears to be very different to the above, which I now know isn't what I initially thought it to be.

[Rich Lee]

When you take off to the west from LAX on a smog alert day the brown smog above the horizon, ocean blue below AI would be very appropriate.

I am a bit puzzled by all this. Is anyone aware of an accident directly attributed to the colour scheme, or IO/OI design of an AI?

So far this discussion seems a bit like arguing which is the better design - black shoes or brown shoes?

[Jetstream Rider]

Just to be clear here, I don't want an argument. I'm interested in hearing other (most respected) people's views about something that at the moment I find quite odd.

Having said that I don't want to hijack the thread, but I find the human factor thing really interesting and hearing from others makes it more so. The pics posted above are to clear up any misunderstanding of what I mentioned above, which is quite clearly not what John Farley meant in the first place.

[Double Zero]

The chap mentioning 'brown or black shoes' clearly hasn't been in a situation where clear, intuative displays might save the collective arses of himself & any passengers.

Personally I'd like 'standby' traditional instruments a bit more prominent - it's unwise to rely on glass cockpits in case of emergency, but companies don't want to admit this - applies to everything from airliners to fighters.

[Jetstream Rider]

I'd like standby instruments to be better quality too and in a standard layout.

[Nigd3]

Maybe someone who has flown a "Highways in the sky" type of EVS can give an opinion on how intuitive they are to fly.
I believe it uses a similar principle to the Russian O-I ADI, in that the horizon is fixed and the aircraft symbol moves in relation to it?

Double Zero, you might just want to retract what you said previously about RL
Our latest cockpit doesnt have any traditional (electro-mechanical) standby instruments. The SFD is backed up by an independent battery, for a main battery and generator failure, that also powers independent sensors for air data and attitude, as obviously required by regulations. In the case of a "simple" PFD failure, the NAV is also connected to it, hence the SFD can display QDM, QDR, GS, LOC and DME. Give me that over an E2B and mechanical ADI and Alt any day.

JR - please don't feel you are hijacking the thread. The HF side of cockpit designs are exactly what I would like information on.

[Nigd3]

JR

With regards your links to Yak-18T photos, the first link looks to be an Aussie registered aircraft....that explains that, the AI is confused when it went down to the southern hemisphere and hence upside down ............. that is very weird with the blue representing the ground.

The second photo link is showing a very old grey-sky/black for ground, which is not so confusing as the first AI.

I can't tell if they are O-I or I-O with the attitudes shown. Maybe someone with better eyesight can clarify.

RL - I don't know if any accidents have been directly attributed to confusion caused by the type of AI installed in the aircraft. I would imagine the greatest problem with determining that is asking the best person afterwards. I do know that significant sim type testing using instantly displayed UA's and then measuring response time to correct, degree of control movement and also correct control movement to recover the aircraft, came down quite heavily in favour of the Russioan O-I ADI. The O-I gave a faster response for recovery and also fewer erroneous corrections.

[hugel]

It is rarely possible to star with a blank sheet of paper designing a cockpit layout. There are historical positionings and conventions, cultural preferences (left to right, top to bottom you say ?) .

There is an interesting Airbus Flight Ops Briefing Note: Human Factors Aspects in Incidents/Accidents in which the Operations Golden rules which address possible causal effects under the heading of "Use of Automation" cite:

• Lack of situational awareness
• Interaction with Automation
• Overreliance on automation
• Lack of Crew Cross Check

It also supplies a number of examples of possible hazards which can result from such interaction. My point in mentioning this is that in an integrated instrument suite, almost any aspect of the HMI can cause such problems if the pilot is abstracted from full control.

For example, if a certain status information is missing from a display format then it may be assumed by the pilot that it is invalid (as one generally hides non valid display data) but it may simply have been moved in a software update to a different panel layout in this new cockpit...

re. comments on physical reversionary instrument more reliable: glass cockpits are great for presenting fused sensor inputs, and integrated displays. The theory is that NTD displays can be routed to any identical glass panel in the cockpit in the event of a hardware failure so should providing redundancy of display device as well as source.

hugel

[hugel]

Another thing worth mentioning is that type commonality to reduce type training within a family is a major factor in new cockpit design. Propogating initial flight deck layouts formats and features across an aircraft family is encouraged and redefining a switch caption or position may have huge ramifications.

hugel

[Double Zero]

NIGD3,

Thanks, but I won't be retracting anything much soon.

My source was various Test Pilots - I, though not a pilot, was alongside them, sometimes literally.

I would hope, and understand it is the case ( ? ) that main standby instruments are pretty much in a standard configuration whether Boeing, Airbus, whatever - & the same is begiining to apply to military aircraft ?

I can't help thinking that along with a RAT for control surface hydraulics, one can barely imagine a much better place for a solar panel to handle electrics / keep a standby battery topped up than the upper surface of an airliner.

Of course this would require a cleaning system, therefore money; I remember being at a Scottish test range when the c/o organised an air to air photo-shoot from an Andover ( thankfully I was not involved ) and all the shots showed the upper surfaces of the Buccaneer covered in Guano !

It's quite a big aircraft, wings way above head level ( have a look at the undercarriage up close ) but it didn't say much for inspection procedures.

[FlightTester]

Please explain...

Sorry to start thread drift, but can you please explain what appears to be a somewaht Luddite view based on the comment below

Personally I'd like 'standby' traditional instruments a bit more prominent - it's unwise to rely on glass cockpits in case of emergency, but companies don't want to admit this - applies to everything from airliners to fighters.

In all the Pt 25 aircraft I fly there are zero "traditional" standby instruments, they're all glass cockpits including the EISI (Electronic Integrated Standby Instrument). The EISI meets in all ways FAR's 1301 and 1309 and as far as I'm aware there has never been a case whereby both ADC's (also electronic) have failed at the same time as all four flight displays and the EISI and left the crew in the dark with no flight information.

Getting back onto the thread and the HMI - if one did think about having the AI IO or OI blue over brown or brown over blue, then you would have to convince the manufacturers of the stand alone EISI or it's equivalent to conform too.

[Jetstream Rider]

See here:

Air Accidents Investigation Branch: S2/2005 Airbus A319-131, G-EUOB

5 mins avail on the standby AI unless they had sorted it.

I don't speak Airbus, so some of this is lost on me, but its pretty serious all the same.

[Milt]

What about our main flight controls?

I have even come across some engine throttle controls where one has to pull a knob towards you to increase power. Another throttle control was positioned under the seat!! No instinct to be found there.

Which way is instinctive for the twist grip engine control in most helicopters?

Then incredulously all of our rudder controls are the wrong way round.

I posted the following some years ago.

Rudders in Reverse

Strange that all aircraft pilots have been retrained away from natural instincts and childhood learning for rudder yaw/directional control.
Most don't even realise that this happened during the first few hours of their training and have rarely been prompted to consider how extraordinary is the result..

Human steering on the ground may have started on horseback as the evolutionary beginning of the human steering process.
Then the learning progression through the tricycle, billycart, bicycle, motorcycle and motor vehicles.

Then go fly and the instructor introduces you to a rudder bar or the equivalent and surprise, surprise it works the opposite way round. Oops.

Generally takes 2/3 hours of diversionary concentration before the reversal starts to become sub-conscious - remember?

Test pilots and purists often speculate on the ability of the experienced pilot to operate nosewheel steering and rudder simultaneously on a landing roll-out without any apparent mental conflict. Perhaps if a nose wheel steering wheel was changed to a miniature rudder bar there would be considerable mental conflict or perhaps we have nerves with selective reversing crossovers.

Oddly I don't recall any difficulty with the tiller in the Beverley which one could imagine to be the spoke of a wheel.

I well remember being caught out in a Folland Gnat having a prototype full slab tail. With gear down at slow speed and normal full nose up trim, full back stick was inadequate to prevent nose down pitch. One was then forced to go for over-ride trim via a two way switch on the instrument panel. Instinctively I selected the switch down as though to instinctively rotate the nose up - Whoops. It had been installed the other way. A green field rapidly enlarging gets your attention. Happily a quick switch reversal sorted things out otherwise I would have had some interesting practice with inverted flying.

[FlightTester]

Thanks JR...

Interesting reading and it has my curiosity peaked. This is one of those situations that should be in the "10 to the minus 9 chance of probability" category so beloved of some of my FMEA colleagues. The five minutes of power remaining for the standby is quite normal in the case of a total electrical failure (FAR 25.1351), but (and this is the main question here) why didn't the RAT or whatever the Airbus equivalent is deploy to restore power? This seems to be a very strange combination of the aircraft apparently losing all power (only reason I can think of for all the displays to go dark) and yet not reverting to standby power automatically. Very strange.

I shall eagerly await the final report!

[Jetstream Rider]

There is a second report a while later. Unfortunately the conclusion is pretty much "we don't know", its still worth a read though.

Air Accidents Investigation Branch: S3/2006 Airbus A319-131, G-EUOB

There appear to be a fair few things that "can't happen" having happened in aircraft accidents, which is why I never believe anyone who says "oh don't worry, that can't happen"

Milt - I've never found the rudder to be backwards. If you see it as a "bar" like handlebars on a bike I can understand why it is thought to be backwards, but why would one want to roll right and use left rudder in a normally balanced turn? That seems very odd to me. It seems entirely natural to push right, go right. I would find it very odd to push right, go left. I do know others who think it is backwards and have the same opinion to you, so there is obviously no universal correct way round. Every time I have thought about it though, having it in a different sense seems mightily odd. Steering down the runway would be even more like chasing a fox!

There is a light aircraft around with reversed aileron controls. It has a control wheel and is from the 30's I believe - can't think of its name. I have a feeling the Shuttleworth collection had some input to its restoration, but otherwise my memory of it is hazy.

[Double Zero]

Shirley,

This is why ground checks waggling the control surfaces with someone the pilot can trust as an external observer to give a 'thumbs up' is worth their weight in gold.

Might cost airlines a precious couple of minutes - tough !

[FlightTester]

Counterintuitive?

I find it quite natural on the rudder to push left go left, but there again I also ride a motorcycle.

Then the learning progression through the tricycle, billycart, bicycle, motorcycle and motor vehicles.

I know it sounds counterintuitive but on a motorcycle at any speed above a walking pace in order to go left you push left on the bars. This draws a nice parallel to the rudder pedals/bar, I think of it as an increase in the pressure of my hand or foot in the direction I want to go.