Rescue 116 Crash at Blackrock, Co Mayo(Mod note in post 1)

Shane_ef wrote: »

A combination of the weather, there altitude, there speed, the lighthouse elevation and the interval

Plus the strobes and lights mounted around the helicopter going off every few seconds and reflecting/bouncing off the clouds just above the helicopter.

Gaoth Laidir wrote: »

Just a note, that should read 8 NM, not km. A few people have used km tonight, which may lead to confusion. 8 NM is about 15 km.

I stand corrected.

Irish Steve wrote: »

Depending on the weather at the time, it's possible that the light was in cloud, the light is 292 282 Ft, the cloudbase was estimated as being 300 Ft, so if the aftercast was even slightly wrong, the light may not have been visible

Surface visibility at Belmullet was reported as 3 km, but at 200 ft altitude it would have been even less. However, even at 3 km visibility, flying at 80 knots (41 m/s) and with a 12-second period of the lighthouse beam, they would have only seen a flash every 500 metres of travel, so around a total of 6 flashes within their visibility range of 3 km. Flight visibility just below cloud base would have been much less than that, so in reality there may have only been 1 or 2 flashes visible to them.

Puzzles me that the crew’s beacons had been installed in the same pouch as the GPS antenna and the beacon manufacturer recommends a distance of 30cm .
This issue plus the software issue need to be sorted for present crews of SAR

I think there should be a reconstruction, via flight simulator , to show how the Black Rock Lighthouse (meant for ships) would look to a Helicopter...

I think it would clear up a lot of misconceptions..

would the "pitch up" suggest their avoidance technique was to raise altitude as opposed to a movement right, as was suggest initially by the crew?

Irish Steve wrote: »

I do. Most Radalts are configured to stop indicating above 2500 Ft indicated, for exactly that reason. The radio return at that stage is no longer strong enough to be reliable.

EGPWS can also use the height information that comes from the GPS system, but even then there can be issues where an aircraft enters a wide valley that has significant high ground either side and ahead if the ground rises rapidly, that was one of the reasons for the change from GPWS to EGPWS. The GPS altitude is as accurate vertically as it is horizontally, and it does not depend on atmospheric pressure, so that potential error is removed.

Your getting into specific systems here, I'm not familiar with the sikorsky s92 EGPWS . It may use gps to derive its altitude. However to provide a accurate height would require it to have a number of satellites and a very accurate clock on board, this is before you take into account the built in inaccuracy in the gps systems courtesy of the USAF.
The captains altimeter usually feeds the information on height to the gpws above whichever height is deemed inaccurate for rad alts.

Irish Steve wrote: »

No, BLKMO is the start point of a pre defined route that takes the aircraft to Blacksod. While AAIU have raised significant concerns about the quality of the approach profiles provided by CHC, they have made no suggestion that the crew had made any error in terms of their intended destination, they will have clear information from the FDR that will indicate exactly where the aircraft had been planned to fly to.




At the time, they were west of Blacksod, and the approach they were about to use was the correct company defined procedure to get into the Blacksod pad, so they were correct to plan to use it

So, how come they were flying at an altitude of 200ft at the start of their approach. That makes no sense.

The report makes for sad reading (like all these reports do I guess...), as other posters have already pointed out it was a combination of several factors all adding up at the same time to cause the tragedy. Even taking any one of the factors away it might not have been as catastrophic, and was a matter of being a handful of seconds too late to react.

Dwarf.Shortage wrote: »

BLKMO is not Blackrock Island, it's nearby but not the island.

I had a look at the approach route from Figure No. 4/I] in the report and superimposed a screenshot from the OSI Map Viewer http://maps.osi.ie/publicviewer/#V2,454024,815435,7,3 over it. Blackrock is only a squiggle on the OSI map but if you toggle on the historic map you can see it very clearly.. It seems BLKMO is either very very close to the island or actually on it so the autopilot may have taken them directly to the waypoint (and the island) at whatever speed and altitude it was set to.

Looking at the CHC approach chart again, the crosshairs at point BLKMO have an annotation '282' which would seem to refer to the height of the light at blackrock lighthouse. There's no ledgend with the chart, so I can't be 100%, but there's also an annotation of '43' at blacksod lighthouse, which is the height of the light at blacksod. So the question is, why were they navigating to a point on the approach chart at an altitude below what was indicated on the chart.

Irish Steve wrote: »

In the light of the (incomplete) information they had available to them, there was no known risk in being at that altitude, and much of their every day activity was carried out at those sorts of levels, so it would not have been unusual or out of the ordinary for them to operate at those sorts of altitudes

Having said that, my anticipation initially, in the absence of information about a standard company approach was that they would have been crossing Blackrock at about 3000 Ft, and then doing the equivalent of an ILS terminating at about 2 miles south of Blacksod, with a visual transition to land.

But they did have information of a known risk - on the text page mentioned in the report - of blackrock altitude of 310ft. Also the 282ft light at blackrock - annotated on the approach chart. This was missed in their approach briefing.

Roger_007 wrote: »

I still think that the simple explanation is that the wrong destination was fed into the flight management system and it did exactly what it was instructed to.

The AAIU report states that the company approach to blacksod was inserted and checked correctly into the FMS. So there is no question that they were intending blackrock as the destination. The intention was blacksod. The question is why they were at 200ft at waypoint BLKMO

Roger_007 wrote: »

I still think that the simple explanation is that the wrong destination was fed into the flight management system and it did exactly what it was instructed to.

The report says nothing of the sort and to be honest I am getting really ticked off with this ill informed response.

Please explain how you came to this conclusion and why you should not be banned from this forum for ignoring all the previous warnings.

There seem to be a couple of misconceptions here that could do with being cleared up:

Navigating 'direct to' a waypoint is not the same as making that point your destination.
BLKMO was selected as the next waypoint to navigate, in the knowledge that they would continue on to a few more waypoints before arriving at Blacksod.

From the CVR transcript:

One point three err miles
to run to eh blackmo…
and after that its bravo
kilo sierra delta alpha

The "standard company approach" followed is not a Precision Approach, in that it does not include vertical guidance, and is really just a lateral route to Blacksod. Unlike a runway ILS, there was no radio beam for the aircraft to follow down to the Blacksod pad.

The vertical descent here serves a different purpose to an ILS approach or similar. The descent is being conducted in order to break through the clouds and gain visual reference for the rest of the flight. The descent was done well out from Blacksod in order to come to a low level over water that was unfortunately misunderstood to be obstacle and terrain free. The rest of the flight to Blacksod was intended to be carried out at this altitude, with the surface in sight, and with enough visibility to see and avoid terrain.

In a way, the word "approach" may have given the wrong idea to some people. The low altitude is not indicative of a desire to land soon, but of an intention to transition from instrument to visual flight rules.