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  #1  
Old 02-09-2017, 06:18 PM
rjtjrt rjtjrt is offline
 
Join Date: Mar 2006
Location: Australia
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Default Synthetic Vision Failure Incident - Safety Report

http://www.atsb.gov.au/media/5772247...-064-final.pdf

This is a report from Australian Safety Bureau, relating to synthetic vision misleading indication on take-off.

Whilst this is due to misleading input from rad alt causing the sythetic vision to malfunction, it is still of note that Synthetic Vision is fallible, and highly experienced pilots had enormous difficulty ignoring the false display even when they realised it was misleading, as well as the usefulness of a standby instrument that did not have synthetic vision.

Last edited by rjtjrt : 02-10-2017 at 05:52 PM. Reason: Spelling
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  #2  
Old 02-10-2017, 10:40 AM
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jjconstant jjconstant is offline
 
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Default

Great post. I'm about to install an EFIS with Synthetic Vision and start my instrument training. Really good to know about failure modes and where to look! Thanks.
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  #3  
Old 02-10-2017, 02:25 PM
springer springer is offline
 
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Default VSI

I am not a fan of a tape VSI on a PFD vs a pointer for instant readability.
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  #4  
Old 02-10-2017, 03:58 PM
Canadian_JOY Canadian_JOY is offline
 
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Very interesting indeed. Thank you for pointing out this report.

When reading what Honeywell was considering as corrective actions, I was left wondering what level of cross-check/comparison is being done by the multiple sensors on the aircraft; GPS x 2, Radalt x 2, AHARS x2, and who knows what else. Having the synthetic vision so heavily reliant on RADALT seems highly unwise. Somebody failed to do a full FMECA on this system, or so it would seem.
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  #5  
Old 02-10-2017, 06:52 PM
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fl-mike fl-mike is offline
 
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Also makes a strong case for an independent standby ESI, in this case an L3 Trilogy vs the Honeywell primary.
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  #6  
Old 02-11-2017, 06:49 AM
F1R F1R is offline
 
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Default Imagine if it was IMC at 50ft AGL

If there had of been a low overcast or fog layer in this case , say at 50ft, and you have both large primary displays showing and telling you to pull up how would you catch on quick enough to trust or even look at the small back up?
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  #7  
Old 02-11-2017, 10:03 AM
rongawer rongawer is offline
 
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Quote:
Originally Posted by F1R View Post
If there had of been a low overcast or fog layer in this case , say at 50ft, and you have both large primary displays showing and telling you to pull up how would you catch on quick enough to trust or even look at the small back up?
I think this is a great question that should be asked by more pilots who launch off into the flag. My guess is that the question exists, but isn't verbalized.

I have SV and love it. However, what you're asking is interesting and speaks to actually using SV.

First off, there is the certified aspect of needing an independent backup within the pilot's view (this is has a defined angle and lateral separation requirement in the reg's). If the primary display failed and you had a properly installed backup, it should be fine - assuming you're trained and proficient with your instruments.

Second is the requirement for backup in an experimental airplane, as in - there isn't one.

Now, for the common sense approach. I never take off of an airport that I can't land at. A 50 foot ceiling is well below any legal instrument approaches for standard GA aircraft, which 200' AGL is lowest precision approach minimum I know of, and you'd certainly have very little time to react to any changes, let alone failures.

My direct response to your question is that, no, I doubt you'd have much time to react to anything with a 50' foot ceiling. Considering a 500 fpm descent rate for landing, that's only 6 seconds from the time breaking out to impact; not much time for any reaction - let alone instrument failure determination.

Now, a question I have is "do you trust SV for landing in non-visual conditions?". It's not legal to use SV in lieu of having the runway environment visually, but if you have an emergency - you can use any means necessary, which would include SV, to safety land. For the record, I've used a safety pilot and landed under the hood on SV - right down the centerline.
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  #8  
Old 02-11-2017, 11:57 AM
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fl-mike fl-mike is offline
 
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As Canadian Joy pointed out, failure of the radar alt causing the primary EFIS SV to go "wonky" is a FMEA case that seems to have not been addressed. If the RA is such a significant contributor to that function, failure of the RA should clearly be annunciated and probably shut off SV. I would surmise that the RA is only used so significantly for low altitude phases, and may have been missed in the FMEA for that particular phase of flight. Just a guess.
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  #9  
Old 02-11-2017, 07:44 PM
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Auburntsts Auburntsts is online now
 
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Quote:
Originally Posted by jjconstant View Post
Great post. I'm about to install an EFIS with Synthetic Vision and start my instrument training. Really good to know about failure modes and where to look! Thanks.
I highly recommend that you turn the SV off until you earn your rating. SV can become a distraction. IMO your scan needs to be rock solid without having to rely on augmented presentations like SV or even HITS/Pathways.
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Last edited by Auburntsts : 02-11-2017 at 07:51 PM.
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  #10  
Old 02-16-2017, 07:24 PM
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n82rb n82rb is offline
 
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i understand that having the SV show bad information will be distracting, but it sounds like this crew was almost using it as primary information. i assume that the aircraft had dual AHRS dual FD, and FMS. so pitch and roll should have been accurate on both screens. if the cross hairs were in the box and the IVSI showed climb on both screens that should have been primary information. automation dependency is rapidly becoming a very major issue in avaition today.

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