AAIB Bulletin: Morecambe Bay
Join Date: Jul 2006
Location: Ban Don Ling
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Mars,
I think the AAIB, not knowing where the lower bug was set because of damage to it post accident (though thought to be 200' as the PIC called, but not acknowledged by the co-pilot with his set at 500') correctly stated that one could have cancelled the other as they had the same priority - "CHECK HEIGHT (pause) CHECK HEIGHT" takes a lot longer to say than "dubublub 100 feet". If the 100 feet had not sounded then there was something very wrong with the AVAD.
But I think you miss the point - the finger is pointing toward the lack of organizational material addressing how the crew should have reacted to such events. The description 'relaxed atmosphere' can also be construed in several ways. You say what you think should have happened according to your OM - AAIB says there was nothing clear in the procedures provided to this crew. Hence the call for re-writes of the OM. I don't think it is the AAIB that needs to brush up on its offshore knowledge!!
I think the AAIB, not knowing where the lower bug was set because of damage to it post accident (though thought to be 200' as the PIC called, but not acknowledged by the co-pilot with his set at 500') correctly stated that one could have cancelled the other as they had the same priority - "CHECK HEIGHT (pause) CHECK HEIGHT" takes a lot longer to say than "dubublub 100 feet". If the 100 feet had not sounded then there was something very wrong with the AVAD.
But I think you miss the point - the finger is pointing toward the lack of organizational material addressing how the crew should have reacted to such events. The description 'relaxed atmosphere' can also be construed in several ways. You say what you think should have happened according to your OM - AAIB says there was nothing clear in the procedures provided to this crew. Hence the call for re-writes of the OM. I don't think it is the AAIB that needs to brush up on its offshore knowledge!!
Join Date: Nov 2001
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Mars, sorry I must disagree with you. '100 ft' call occurs on almost every landing, except those where you cross the deck above 100' and the system detects more than 5000 ft /min measured ROD. It certainly occurs on every onshore landing. Therefore its no good treating it like a GPWS Pullup or even getting excited about it at all. I think you are confusing with 'Check Height' which should not normally be heard - when you intend to descend below bugged height you use the suspend button to prevent the nuisance -or cry wolf - warning. If you do get a check height, you most certainly should be doing something about it.
Since the 100' call is not suspendable but the check height is, its highly likely that the report is correct in this respect.
HOMP/FDM does not generate an event from any AVAD warnings since that information is not available on the data stream. HOMP does have minimum altitudes for en-route flying which could trigger an event, but there can't be a simple "too low" event during the landing phase because you are intending to end up at zero feet before you land! Our system does have a "too low more than x distance from offshore touchdown at night" event but what constitutes too low, and what x is, are secret and nothing to do with radalt settings or AVAD!
Since the 100' call is not suspendable but the check height is, its highly likely that the report is correct in this respect.
HOMP/FDM does not generate an event from any AVAD warnings since that information is not available on the data stream. HOMP does have minimum altitudes for en-route flying which could trigger an event, but there can't be a simple "too low" event during the landing phase because you are intending to end up at zero feet before you land! Our system does have a "too low more than x distance from offshore touchdown at night" event but what constitutes too low, and what x is, are secret and nothing to do with radalt settings or AVAD!
Join Date: Nov 2005
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On the subject of the AVAD warning, it must be worthy of note that the cockpit switch was set to the "single pilot" position thus causing the "check height" warning only to be heard when the aircraft descends below the bug height set by the RHS pilot, if the suspend button is not used. The bug on the co-pilot's radalt was set to 500ft (Is this standard CHC policy?), but this was disconnected from the AVAD. We do not know where the commander's bug, which was the one connected to the AVAD, was set.
Join Date: Aug 2004
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As a non-IFR pilot (dons nomex underwear), I had a flick through the report and pondered the differences in aids between an approach at EGLL to the one in question here. Isn't a GPWS system one that might have helped here because of its appreciation of both height and more importantly RoD of radalt? If you have a high workload and believe you have just recovered from a stressful situation and get a 100ft warning then you have no immediate concern because you 'know' you are flying straight and level. If you have a differential system and recognise the alert as one that indicates a few seconds until the ground appears (based on Rod+radalt) then you're more likely to focus your attention on dealing with that until it shuts up? In the same way that your eyes would pass on this impetus if the outside world was visible and the ground was approaching rapidly?
Are there any videos of a bad weather night approach? If a picture is worth a thousand words, i think a video is worth even more to convey to those inexperienced with such matters what goes on. I've only found good weather ones on Internet so far and that only really showed the 'at a shallow angle, lots of yellow lights look the same' phenomena.
Are there any videos of a bad weather night approach? If a picture is worth a thousand words, i think a video is worth even more to convey to those inexperienced with such matters what goes on. I've only found good weather ones on Internet so far and that only really showed the 'at a shallow angle, lots of yellow lights look the same' phenomena.
Join Date: Nov 2005
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FWF,
I agree, EGPWS can be configured to offer multiple warnings and alerts depending on the type of operation, and I think in a case like this it might have helped the crew's situational awareness and aided quicker recognition of the PF's loss of control. I have witnessed EGPWS in use over land but i'm not quite sure of the set up and effectiveness of it over the sea, perhaps some offshore pilots familiar with the system can comment on that? Like most things in aviation it usually comes down to money...
BC
I agree, EGPWS can be configured to offer multiple warnings and alerts depending on the type of operation, and I think in a case like this it might have helped the crew's situational awareness and aided quicker recognition of the PF's loss of control. I have witnessed EGPWS in use over land but i'm not quite sure of the set up and effectiveness of it over the sea, perhaps some offshore pilots familiar with the system can comment on that? Like most things in aviation it usually comes down to money...
BC
Join Date: Aug 2001
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Night Appraoches and EGPWS
Video - YouTube - helicopter landing on platform at night
The otherwise excellent EGPWS in the context of offshore ops has some serious holes in it. The system can use terrain or obstructions as the datum for a series of proximity warnings that can include excessive RoD and ILS glideslope. Unfortunately it doesn't know where all the obstructions (platforms, rigs, ships etc) are so when you make an approach it can't figure that you actually want to land on the 'obstruction'.
I have yet to play with EGPWS for real but I'm sure there are folk out there who can contribute their first-hand experience but I do remember that when I asked Sikorsky some years ago about this problem I was met with a blank stare and a crooked smile that conveyed a huge gap in their appreciation of the problem.
Then we have the debate about whether EGPWS is a substitute for AVAD. I don't think they got that right either.
G
The otherwise excellent EGPWS in the context of offshore ops has some serious holes in it. The system can use terrain or obstructions as the datum for a series of proximity warnings that can include excessive RoD and ILS glideslope. Unfortunately it doesn't know where all the obstructions (platforms, rigs, ships etc) are so when you make an approach it can't figure that you actually want to land on the 'obstruction'.
I have yet to play with EGPWS for real but I'm sure there are folk out there who can contribute their first-hand experience but I do remember that when I asked Sikorsky some years ago about this problem I was met with a blank stare and a crooked smile that conveyed a huge gap in their appreciation of the problem.
Then we have the debate about whether EGPWS is a substitute for AVAD. I don't think they got that right either.
G
