SAR S-92 Missing Ireland
Joined: Dec 2013
Posts: 1
Likes: 0
From: Norfolk
The how is easy, the aircraft was flying below MSA for the area.
The why, is because the crew hadn't got a clue they were below MSA due to inadequacies in the charts they were using.
They knew perfectly well where they were, the chart displayed just didn't show them to be in any danger. That led to confusion when an obstruction was identified ahead, because the chart would be expected to show anything large or tall enough to cause danger to the aircraft.
It really doesn't have to be any more complicated than that.
The why, is because the crew hadn't got a clue they were below MSA due to inadequacies in the charts they were using.
They knew perfectly well where they were, the chart displayed just didn't show them to be in any danger. That led to confusion when an obstruction was identified ahead, because the chart would be expected to show anything large or tall enough to cause danger to the aircraft.
It really doesn't have to be any more complicated than that.
Joined: Oct 2006
Posts: 268
Likes: 0
From: Florida
The how is easy, the aircraft was flying below MSA for the area.
The why, is because the crew hadn't got a clue they were below MSA due to inadequacies in the charts they were using.
They knew perfectly well where they were, the chart displayed just didn't show them to be in any danger. That led to confusion when an obstruction was identified ahead, because the chart would be expected to show anything large or tall enough to cause danger to the aircraft.
It really doesn't have to be any more complicated than that.
The why, is because the crew hadn't got a clue they were below MSA due to inadequacies in the charts they were using.
They knew perfectly well where they were, the chart displayed just didn't show them to be in any danger. That led to confusion when an obstruction was identified ahead, because the chart would be expected to show anything large or tall enough to cause danger to the aircraft.
It really doesn't have to be any more complicated than that.
Before "Ze Germans" get here
Joined: Apr 2003
Posts: 319
Likes: 0
From: ?
Joined: May 2010
Posts: 1,570
Likes: 374
From: PLanet Earth
No you don't know if your (electronic) maps don't show any obstacles higher than 30ft. In hindsight obviously we know better.
It is sad to see how a combination of inexact information and certain logic in the equipment that by itself would not cause a big risk/problem (280ft high obstacle in open sea not shown in EGPWS database, not or only partly shown in moving map, depending on mode, EGPWS inhibition in low altitude mode, deactivated clutter suppression, in exactly this combination lining up for a perfect disaster) still makes such a scenario possible even in such a modern machine. Very enlightening regarding unwanted consequences of features.
Why they cruised at 200ft for such an extended period of time will probably remain a mystery, though.
Joined: Apr 2005
Posts: 429
Likes: 38
From: England
Henry,
I don't know what rules you work to but I have always known msa to be 1000 ft about highest object. At 200 ft you are therefore obviously below msa regardless of what your paper or electronic map says.
Offshore MSA is 1000ft or 1500ft in areas of wind turbines.
I don't know what rules you work to but I have always known msa to be 1000 ft about highest object. At 200 ft you are therefore obviously below msa regardless of what your paper or electronic map says.
Offshore MSA is 1000ft or 1500ft in areas of wind turbines.
Joined: Apr 2005
Posts: 280
Likes: 20
From: OZ
Why they cruised at 200ft for such an extended period of time will probably remain a mystery, though.
One scenario is that they "let down" over the ocean. Got clear of cloud. Then followed a route (clear of cloud, but in the dark?) at a height they thought they were safe at.
Any mystery in my mind is why they thought the route was safe at 200'.
The tragedy in my mind is all the safety back stops not working, especially EGWPS.
Joined: Aug 2001
Posts: 1,308
Likes: 0
From: Cornwall
Jeepys - We are talking SAR here and there are different rules for them that take into account their mission, the training and the equipment on board. Read the previous posts and you will get the picture.
G
G
Joined: Dec 2013
Posts: 225
Likes: 29
From: UK
Jeepsys - this has all been discussed in depth in previous pages if you care to look. It just needs a bit of effort but to help you - the AAIU Preliminary Report on this accident is referenced in post 840 on page 42 of this thread. On page 17 of the report, para 3.5.8, the Operator's Route Guide is displayed. Read the report and this thread from thereon in and your queries will be answered.
Joined: Apr 2005
Posts: 280
Likes: 20
From: OZ
For the jeep seats:
As stated further up this page. They "let down" over the sea. A common, and safe practice.
They were using a company VFR route guide. To get to the refueling destination.
Not a "let down route". No vertical guidance. Spot heights were included on the second page.
This is only my understanding from reading the report, with both eyes open, some experience, and a healthy interest.
As stated further up this page. They "let down" over the sea. A common, and safe practice.
They were using a company VFR route guide. To get to the refueling destination.
Not a "let down route". No vertical guidance. Spot heights were included on the second page.
This is only my understanding from reading the report, with both eyes open, some experience, and a healthy interest.
Joined: Dec 2007
Posts: 595
Likes: 58
From: UK
Nice to get the 'before landing checks' done before decending so low in bad weather, also depending on what was going on in their mental model they may have been planning on coming in slower and lower, so prevents the landing gear warning
Joined: Apr 2017
Posts: 6
Likes: 0
From: Dublin
I posted earlier, Irish Aviation Authority VFR maps use a red circle as the symbol for a lighthouse. You can see Black Rock and Blacksod lighthouses and their heights marked on the company map (282 and 43)