The seeds of the destruction of Rescue 116, and the deaths of its crew, may have been sown long before the Coastguard Sikorsky S92 helicopter took off from Dublin on its last flight.
R116 travelled to lend assistance to an already under way rescue mission involving its sister ship, the Sligo-based R118. R116 was providing what the coastguard calls “top cover”.
It would not participate in the actual rescue of an injured crewman aboard a trawler off the west coast, but instead would provide “just in case” security to the aircraft already doing so.
R116 would not have been deployed had the Air Corps been in a position to provide an aircraft
R116 would not have been deployed had the Air Corps been in a position to provide an aircraft. However, its long-range Casa Fisheries Patrol aircraft were grounded due to a lack of trained crew to fly them around the clock.
The weather was poor with strong winds and low cloud and rain hampering visibility from 300ft up. R116, having crossed as far as the Mayo coast off Blacksod Bay, needed to refuel. The designated refuelling point was beside Blacksod Lighthouse, on the southern tip of the peninsula.
The recommended approach was from inside Blacksod Bay, from the east of the lighthouse. To get there safely, in the windy murk, it need to descend safely from its cruising altitude of 4,000ft above sea level and approach Blacksod Bay from further out to sea on a trajectory that safely took it clear of obstacles like islands and even Blacksod Lighthouse itself.
Navigational waypoint
Then, having reached a predetermined point within Blacksod Bay, R116 could then take a westerly track back towards the helipad at the lighthouse.
But to commence its low approach across the sea to Blacksod, R116 needed an accurate starting point. In navigation terms this is called a waypoint and it is a GPS or SatNav location that is pre-programmed into the navigation computer.
R116 descended to 200ft and started its passage in the dark towards the pre-programmed waypoint known as BLCKMO. From there, the plan was to take a left turn towards Blacksod and navigate safely past another two waypoints before making what should have been, despite the darkness and rain, a safe approach to the helipad.
As R116 started this manoeuvre, it did so from the far side of the 300ft-high island crag of Blackrock and its crew had selected a navigation command termed “direct to BLCKMO” which would take it directly to that waypoint, irrespective of what might be in the way.
Unfortunately, Blackrock itself was in the way.
Electronic gadgetry
Compared to Ireland’s first rescue helicopter, the Aerospatiale Allouette, which boasted a simple compass as its only navigation aid, R116 was bristling with sophisticated electronic gadgetry.
Apart from radar and other equipment, it had an Enhanced Ground Proximity Warning System (EGPWS) which was an improvement on its predecessor, Ground Proximity Warning System (GPWS) which was also installed. While GPWS issues a cockpit alert when it detects rising ground, like the foothills of a mountain, it was of limited use when an aircraft was about to hit rapidly rising terrain like a tall building or a precipitous cliff. This was because the radar-like signal was directed downwards and an aircraft might have already collided with an object before the GPWS detected it.
EGPWS solved this problem by having electronic scans of the hazardous topography an aircraft was likely to encounter already programmed into its operating computer so that when the pilots approached a hazard, its imagery appeared on their cockpit screens and they knew what they were dealing with.
Sadly, imagery of Blackrock was omitted from R116's EGPWS because its scan supplier was unhappy with the accuracy of the Blackrock imagery available
Sadly, imagery of Blackrock was omitted from R116’s EGPWS because, as the Air Accident Investigation Unit (AAIU) interim report states, its scan supplier was unhappy with the accuracy of the Blackrock imagery available.
Ideal world
In an ideal world, helicopter pilots might have spotted Blackrock using radar or standard maps and charts and, indeed, it was spotted on radar at the last moment.
But this was far from being an ideal world. Blackrock is capped by a lighthouse, the strong beam of which can easily be seen from miles away, but low cloud probably meant this was obscured.
Added to this, the east coast crew was unfamiliar with this part of the west coast and had rarely ventured there at night. They received a GPWS warning of rising terrain shortly before the accident but presumably assumed it to be an isolated small rock of little consequence. The pilots may have been confused at this stage at the messages they were receiving, especially given the fact that the flight management computer appeared to be taking them to a safe waypoint.
One of the winchmen in the rear of the aircraft almost saved the day when he realised the image coming up on the screen he would normally use to help direct pilots to hover over a casualty was that of a large island with steeply rising cliffs. He called on the pilot to immediately turn and the transcript from the cockpit voice recorder makes chilling reading.
Small target
When co-pilot Mark Duffy says "Okay so small target at six miles eleven o'clock. Large out to the right there ehm", Capt Dara Fitzpatrick says "Eh just a small little island . . . that's B L M O itself".
Then the winchman interjects “Looking at an island just in, directly ahead of us now guys, you want to come right.”
The examination of the wreckage shows that the helicopter adopted a steep nose-up attitude, presumably as it attempted to clear the steep cliff it was heading towards, and it appears to have almost made it until the tail rotor hit a small outhouse associated with the lighthouse complex.
Despite losing the tail rotor, the helicopter continued to fly for another few seconds until it came down in the sea on the other side of the island. The black box printout suggests it was an erratic and, to say the least, uncomfortable few seconds.
Another mystery of the loss of R116 was why it took so long to find both the crew (two are still missing) and the helicopter itself. The helicopter was equipped with an emergency locator beacon which should have alerted early responders to its location but this was found to have been smashed some time during the incident and could not have functioned.
And why did it take so long to find the crew? One answer is that the emergency beacons they wore and which should have guided rescuers directly to them appear to have failed to work. The investigation has called for these to be further investigated and suggested they were improperly installed.
Could the two still-missing crewmen, Paul Ormsby and Ciaran Smith, have been found if the devices were working properly? Could the life of Capt Fitzpatrick have been saved if she was found earlier, instead of hours after the helicopter crashed?
These questions are best left to the final report from the AAIU.
Gerry Byrne is an aviation journalist and author of Flight 427: Anatomy of an Air Disaster (Copernicus Books, New York)