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Old 18th Apr 2017, 19:48
  #1196 (permalink)  
cncpc
 
Join Date: Nov 2015
Location: Canada
Posts: 105
Originally Posted by Tezzer 007 View Post
They inputted BLKMO into the FMS. BLKMO is Black Rock.
Yes, it is, as it turns out. That does not mean the crew were aware that it was a waypoint that was located with a rock sticking 300 feet out of the ocean. They very clearly were not.

In answer to a question posed by Rotorspeed about why they would select an APP1 mode for descent, and whether that was imposed by the operator, it would be helpful to have 5 more minutes of the CVR before what is in the report.

I think the report makes it clear that the APBSS diagram was being used. It is not clear if the waypoints in that diagram are structured into a selectable approach in the FMS. If they are, then that supports a view that this is "imposed by the operator". The next question is if the operator imposes it as an IFR approach. If that is so, it is clearly inadequate, lacking vertical guidance.

There are a couple of features of this diagram that have the potential for the crew being led into the danger of presuming it is an IFR procedure for IMC conditions. The first is the lighter blue shading on either side of the leg lines. That shading only appears over water, except at BLCKMO. It does not appear over any terrain, or so it appears. I expect most would think it indicates an obstacle free safe space. Which it does. Even at 200 feet. Except for Blackrock, or over land around Blacksod.

The second feature is that it cannot be flown visually, although it obviously can be flown VFR. However to go from waypoint to waypoint, the flight must utilize instrumentation in the cockpit. Other than the helipads/lights, the other waypoints cannot be identified visually.

So the waypoints must be in the nav databases of helicopters which use this route. That would have to include the helicopters which use it for its primary purpose, transiting between Blacksod and Blackrock. Those aren't S-92s. But they are helicopters. We know an Air Corps machine was used to place the investigators there. So some other operator has a version of that diagram, and somehow CHC has it in its route guide. Legacy procedure seems reasonable.

It seems this crew has little to no local knowledge. That fact alone, and the availability of APBSS in the aircraft, underly this accident to a considerable degree.

Great discussion on radar. One thing from the CVR that stands out is that the crew operated on an assumption about the environment they were in. They were wrong to believe 200 feet was a safe altitude. When Capt. Duffy says something large to the right, it is obvious that assumption is challenged and that 200 feet, where they are and at 75 knots, may be/was a dangerous place to be and that a climb to MSA was a priority, followed by a different lookdown with the radar. Radar guys, they will see the picture then, or no? SAR pilots, yes or no on the immediate climb?

I would be interested on hearing how synthetic vision gear may have avoided this. Is it true that like EGPWS, if Blackrock isn't in the database, same problem?

If the purpose of the preliminary report is to immediately advise other operators and aircrew of issues, I think another five minutes of immediately preceeding CVR would be very enlightening for that purpose.

Last edited by cncpc; 18th Apr 2017 at 20:12.
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