Flight automation hiding hazards

[John Marsh]

I have seen expressed on the AF447 thread in R&N and elsewhere the concern that flight automation can hide accumulating problems from the flight crew, until the situation becomes too much for the systems to handle. At this point, control of an aircraft in serious difficulty is suddenly returned to the pilots.

Would it make any sense to have a continuous display of the automatic systems' level of activity in mitigating problems in flight? Something like a scrolling graph, with low readings in green covering routine activity, changing colour for higher levels. Yellow, for instance, could trigger an audible warning.

[spannersatcx]

I've not read the thread so can't comment on that. On (most) modern day a/c, including the A330 there are many switches on the overhead panels, the concept is all lights out everything ok. If a light is on it is either selected off or in a non normal position. If the Switch is on and a failure is detected then a light will illuminate in the switch.

This will normally be accompanied by a master caution or warning a chime and a message on ECAM, with the appropriate crew action required.

Certain modes are displayed on the PFD's and should one of these not be correct it will say so.

Some things are not displayed, but are logged in the central maintenance computer and will be actioned on arrival, these are not displayed because the systems have built in redundancy and there is not always a crew action available that could clear the fault.

I think there are enough already available in the systems.

[John Marsh]

Thanks spanners. I was thinking, perhaps too vaguely, of some kind of trend indicator, monitoring the efforts being made by an entirely or mostly 'healthy' aircraft to maintain stable flight. I say this because the AF447 A330 is thus far assumed by PPRuNers to have been mostly healthy, in the cruise, barring any pitot malfunction(s) yet to be ascertained.

[Dan Winterland]

The problem is that the crew will still have to do some sort of evaluation. Often in an aircraft such as the Fly By Wire Airbus types, any solution to a problem is fairly objective - you do the actions as listed on the ECAM and the problem should be resolved to the point where the aircraft can be recovered safely in it's degraded mode. But in a situation where some analysis is required, it's down to the skill and experience of the crew. In the AF447 case, it appears that the disabled sensors got the aircraft thisnking there were a whole load of problems which may not have been there. If this was indeed the case all the crew had to do was click the autopilot out and fly it manually with the degraded instrument indications. A indication of total perfomance available would not have helped them as the aircrtaft itself was not aware of what was happening as the systems thought the information given by the blocked sensors was correct.

The AF447 case is an interesting one. We should know the whole story soon if the FDR data can be read. But as an aside, Cathay Pacific had an almost identical event some years back with icing on the same type of sensors and the same indications. The aircraft was recovered by the crew's actions which required a lot of thinking outside the drills and checklists.

[Piltdown Man]

Such systems are already fitted. At higher levels, the reduced speed range is already displayed, a pitch limit indicator is sometimes displayed and automatically a bank angle limiter is "engaged." But as far as systems are concerned, everything is either normal or something is "bust," a "might be a bit broken" is not an option. Additionally, virtually all system degradations are displayed or announced. As Dan pointed out, it's dealing with these where the skill is required.

PM

[Dan Winterland]

The latest Airbus aircraft have an emergency speed and height indication known as the Backup Speed scale which displays a GPS speed (as a target and a trend rather than a value) and a GPS altitude in place of the regular speed and altitude should the Air Data Computers fail.