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Time for a check?

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Time for a check?

Old 1st Nov 2013, 09:48
  #1 (permalink)  
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Time for a check?

NB Non type specific and civil only:

Is it time to make an objective assessment of any value that FBW and associated software/automatic protection systems have contributed?

We must all be aware of the growing incidence of incidents/accidents 'affected' by the trust or reliance on operating and protection systems, and we all, I'm sure, seek a way to ameliorate these.

Do we have the data to assess (for example) how many terrain avoidance/windshear/approach/ga events have actually been 'saved' by the systems and how many events have been directly or indirectly caused by them?

Not seeking a humungous list, just open for discussion at present with a view to a 'balance sheet' plus a look at how we train for these systems and indeed whether the 'automatics' pendulum should start its backswing. As we move inexorably towards the 'pilotless aircraft' this balance sheet will surely become pivotal.
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Old 1st Nov 2013, 10:31
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The following question should also be asked...

Do we have the data to assess (for example) how many terrain avoidance/windshear/approach/ga events could have actually been 'saved' by the systems if they had been available to non FBW aircraft and how many events could have been directly or indirectly caused by not having them?

All in the interest of balance of course.

Last edited by TURIN; 1st Nov 2013 at 10:32.
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Old 1st Nov 2013, 12:09
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A valid line of investigation, Turin, but although non-FBW 'pilotless aircraft' have successfully flown for many years it is unlikely that they will in the future, so I believe the focus should be on FBW. You also open the catchment area significantly - take the AMS THY 737 - non-FBW, but the accident significantly aggravated by 'failure' of the 'operating and protection systems' ie A/T-RadAlt and Auto-trim, and you add another large dimension to the data sweep. I think we should seek to avoid too many sub-branches.
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Old 1st Nov 2013, 13:53
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When they made the airplanes safer, by adding a whole series of gadgets, flying became indeed more easy. A secondary effect of this was, that many previous knowledge required and common sense was 'not needed' anymore for daily ops.
The overall difference in safety level of an average 3000 hr airline captain, compared to an experienced pilot with a classic aircraft, is therefor a valid question.
I think flightschools and beancounters took an unexpected advantage of the new generation of aircraft.
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Old 1st Nov 2013, 15:17
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I think we need to make careful distinction between systems here. For example, I doubt anyone would seriously question the usefulness of GPWS or TCAS and their beneficial effect in reducing the probability of CFIT and mid-air collisions respectively. Similarly, lateral autopilot modes appear to bring about significant benefits in pilot workload and navigation accuracy without causing problems.

From reading through accident reports and the comments on various PPRuNe threads it seems to me that the problems lie primarily in two areas:

- Misuse or mismanagement of VNAV autopilot modes, particularly if autothrottle is used at the same time;

- Some of the deeper and more complex aspects of flight envelope protection logic in FBW systems, particularly failure modes, and especially if the air data system is compromised.

What do people think about focussing the debate on to these aspects, or should it be wider?
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Old 1st Nov 2013, 15:46
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I would suggest that we could probably focus almost entirely on pitch and power aspects. "GPWS or TCAS" would only drop into my frame if there were any 'automatic' manoeuvres associated.
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Old 1st Nov 2013, 15:47
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Data gathering has been very difficult, as every airline and manufacturer keeps this all very close. Just try to get the FOQA data on your last flight!

There has been some success, with 'blind' agreements with providers of real-time FDM, HFDM, FOQA, MFOQA data. Unfortunately, given the nature of the blind data, when an event is indicated, (by certain reactions of the aircraft systems) it is not possible to talk to the pilots to see what happened.

As an example, there are a few airports the US northeast, where there are crossing altitudes in/out of the airspace with a 500 foot difference in alt. In the data, you will see a TCAS event, but you really dont have a simple way to determine that this was a non-event.

Last edited by underfire; 1st Nov 2013 at 15:48.
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Old 1st Nov 2013, 18:00
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It may be very difficult to form a meaningful assessment of the safety impact of FBW.
First, very few successes are reported; the industry loves to focus on failure.
Second, any differences in the mechanism of control should not directly affect the pilot’s ability to fly (operate) the aircraft. Only envelope protection might stand out as a difference, but even non FBW have some protection – stick force, audio/visual warnings, and the scenarios are rare.

Beyond controls, the safety technologies apply to both types with/without FBW (EGPWS, TCAS, etc), and any detrimental aspects are predominately related to human behavior; particular situation assessment.
EFIS displays etc, might show some benefit with increased information, but see (1). The display of terrain and pop-up alerts for EGPWS might accentuate the warning, and thus contribute to the success of EGPWS.
EICAS displays may aid better fault finding, but there may be fewer faults to find.
Overall this is the area of maximum safety benefit.

I would play-down any automation / skills controversy as each type has the capability for automation/enhanced technology, where any differences are in the level of automation and possibly manufacturer dependent, but none reliant on FBW.

Perhaps the major difference is in training; the extent appears to have reduced, but arguably with more complex systems and greater capability, systems training should have increased. As a result crews are expected the ‘trust’ automation based on minimum knowledge and depend on ‘procedural’ guidance.
As a result, in many instances crews may choose to rely more on technology, attempt to follow SOPs when they might not apply, and seek ‘legal’ cover vice airmanship (understanding of the operational scenario).
However, don’t tie these in with FBW, they result from deliberate human-choice driven by economics. Thus a suitable measure might be of continued success of the industry vs the safety record – at what cost. Most indicators would show a positive swing of the pendulum, yet many forums/posts suggest otherwise. On one hand that’s good (never forget to be afraid), on the other it’s human fickleness. Perhaps we should ask what has the human has contributed to the swing; plus, minus, or interestingly frustrating.
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Old 1st Nov 2013, 18:44
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From our aspect, it is interesting to see the nature of the event from the onboard sensors, look at roll moment, g forces, and altitude changes. This looks at response by the aircraft with the autopilot on, auto-pilot auto disco, and auto-pilot manual disco with pilot intervention...

While there isnt alot of correlation with the actual pilot feedback, there is some. It is very interesting to see the pilots perception of the event vs the recorded data.

This was very interesting and will certainly lead to further studies and such for sure.
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