Originally Posted by
G0ULI
If the route was already preprogrammed into the FMS as a result of previous taskings or appeared as a selectable option...
Hey, someone else has already worked out a routing previously, we'll just follow that. Must be okay, it's stored in the FMS.
Can it really have been as simple as that?
It could have appeared as a simple, safe option to a crew unfamiliar with the area operating in pretty poor weather conditions. Why reinvent the wheel when someone else has apparently already done all the hard work?
Descend to gain sight of the surface over open water, select the route and concentrate on the rest of the mission. An expectation that the route was "safe" because someone must have flown it before, would certainly go a long way to explaining the apparent initial confusion and lack of urgency in changing course in response to the FLIR operator warning of an obstruction ahead.
A land based analogy could easily be drawn with professional lorry drivers blindly following sat nav directions and colliding with low bridges or other hazards when it should be obvious that the route is unsuitable.
I think G0ULI is on the right track.
After R116 returned from its top cover on the 8th, having earlier departed Blacksod , the aircraft underwent a 50 hour maintenance inspection.
It made only a single one hour flight in the East Coast area before the fatal flight.
There is a high probability the waypoints were still in the Euronav system as a recorded previous flight.
On the 8th the AIS shows R116 approached Blacksod via BKSDB and BKSDC however it departed Blacksod via BKSDA and BLKMO. (Their westerly track to the FV went about 400m south of Black Rock so BLKMO must lie along this).
(Note Sligo R118 never adhered to any of these formal approach/departure routes either on the 8th or 13/14th)
So for the R116 crew uncertain of the approach its a simple matter to reverse the previous course to arrive at Blacksod.
All GPS and mapping systems use the same SRTM derived terrain elevation models and will either show mainland only and no islands or will show Black Rock at 50ft.
Lighthouses do not appear in the IAA AIP or Notams so would not be displayed as an obstacle in the GPS. They do appear on the marine charts.
Black Rock was equipped with an AIS beacon but would only show location not height.
The Euronav uses a raster (scanned picture) of the 06 Edition 2013 ICAO VFR Chart 1:250000. On the 1:500000 version the 6 deg isogonal line cuts through the third digit of the lighthouses height value making 282 appear as 28ft. Its likely but needs to be verified that the 1:250000 version has the same defect and also the defect text of obscuring the 206ft height of Duvillaun More which would have alerted them to terrain en-route. In the Euronav vector terrain derived from SRTM can overlaid over the raster chart.
As many here have stated the crew appeared to believe that Black Rock Mayo was a 28ft small island near waypoint BLKMO and were confident that there were no obstacles or terrain in their path and anyway their GPS TAWS and EGPWS and Radar would alert them.
EI