WHY WAS DOOMED R116 FLYING SO LOW?

Inquiry will focus on why helicopter was at 200ft – even though route guide showed an obstacle several feet higher

WHY the doomed crew of Rescue 116 were flying so low while on the ill-fated rescue mission that cost them their lives is set to be a key question in unravelling the continuing mystery.

The ongoing investigation into the worst ever crash involving members of the Coast Guard is likely to focus on why the Sikorsky S-92 helicopter was flying at 200ft – even though an obstacle several feet higher was marked on a route guide of the area used by the crew.

The revelation about the rescue helicopter flying so low was made in the preliminary report into the crash issued by the AAIU (Air Accident Investigation Unit) this week.

Initial media reports focused on why Blackrock island was not included in the helicopter’s EGWS (Enhanced Ground Proximity Warning System) database.

But according to an aviation expert who studied the AAIU’s

‘To have descended to 200ft is very low’

preliminary findings, the crew should have been flying much higher as they flew over Blackrock island on their way to refuel in nearby Blacksod.

The experienced aviation expert, who asked for anonymity to speak freely, told the Irish Mail on Sunday: ‘The ground proximity is really only a casual backup to assist flight crew avoid colliding with the ground.

‘But it is by no means a primary or even a secondary source of navigation – it’s a last line of defence purely to assist the flight crew avoid a collision with the ground or obstacle.

‘To have descended to 200ft above the water is very low for the distance remaining to the landing at Blacksod. It is certainly not uncommon for SAR helicopters to operate at these low levels on actual missions and when training where the operational need dictates.

‘However, it remains unclear as to the reasons for the aircraft to have descended to a level of 200ft so early on in the procedure route particularly with the initial waypoint in the procedure.

‘Blackrock was illustrated on the procedure chart and annotated with a height of 282ft.

‘Usually, all aircraft are required to operate at a minimum of 1500ft altitude above the highest obstacle flying over towns and cities or 500ft above the highest obstacle flying in rural areas. The Coast Guard, Aer Corps, Garda and State aircraft are all exempt from these rules and they have considerable leeway to deviate, albeit with sufficient justification to support doing so.

‘However, the reasons for Rescue 116 to be that low that far out, in excess of 10 nautical miles at the start of the procedure, are likely to be crucial to the investigation.’

The expert pointed out that one aspect that hadn’t been detailed was the vertical profile. A vertical profile details what altitude an aircraft should be flying so that all known obstacles listed in a route guide can be safely cleared.

The expert added: ‘Looking at Figure 4 in the report it shows an extract of the procedure (flight path) which would have been an internal company-developed procedure, and it has Blackrock island and lighthouse illustrated on it, including its height of 282ft.

‘There is usually another section or page detailing the vertical profile to be flown in conjunction with the lateral profile illustrated in Figure 4.

‘The vertical profile essentially details the altitudes at the various stages or waypoints along the route that the aircraft should be flying at, to ensure obstacle clearance. It will give the altitude you should be flying at so that even if you can’t see the obstacle you will clear such obstacles by a safe margin.

When the MoS asked the AAIU about the vertical profile – which would detail the altitude at which the helicopter should have been flying – the AAIU refused to comment on its preliminary report. And when the MoS asked for a copy of the vertical profile for the route map that the doomed crew were using, the AAIU referred the MoS to one of its two interim safety recommendations, which refers to vertical profiles.

It reads: ‘CHC Ireland should review/re-evaluate all route guides in use by its SAR helicopters in Ireland, with a view to enhancing the information provided on obstacle heights and positions, terrain clearance, vertical profile, the positions of waypoints in relation to obstacles and EGPWS (Enhanced Ground Proximity Warning System) database terrain and obstacle limitations.’ Captain Dara Fitzpatrick, co-pilot Mark Duffy and winchmen Paul Ormsby and Ciarán Smith were on board Rescue 116 when it crashed on March 14.

The Dublin-based crew were providing back-up for Coast Guard colleagues from Sligo called out to airlift an injured fisherman working on board a trawler. The crew were on their way to refuel when the crash happened.

The bodies of the pilot and her co-pilot were later recovered. The search continues for the other two missing crewmen.

The Coast Guard rescue service is provided by a private company called CHC.

When the MoS asked the company this weekend to provide details about the vertical profile for the route guide the 116 crew were using on their last flight, a spokesman for the company declined to do so.

‘Why they were that low will be a crucial question’ ‘The vertical profile gives the flying height’