Public Service

Irish Crash Probe Plumbs Why Island Wasn’t in Terrain Database

By James T. McKenna | April 14, 2017
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Black rock island

Black Rock Island. Photo courtesy of the Commissioners of Irish Lights

International investigators led by Ireland are assessing, among other factors, why a quarter-mile-long island is not in the terrain-awareness database of a S-92 that crashed on it in the first hour of March 14, killing all four crewmembers.

Ireland's Air Accident Investigation Unit said Honeywell, which made the Sikorsky aircraft's Mark 22 Enhanced Ground Proximity Warning System, told its investigators that Black Rock Island and a 49-foot-tall lighthouse that sits on it or not in the system’s terrain database. This detail is contained in the preliminary report on the Irish Coast Guard fatal accident released by the investigation unit today.


The report says Honeywell told investigators, “The lighthouse obstacle is not in the obstacle database and the terrain of the island is not in our terrain database.” The avionics maker offered the explanation, the report says, that it integrates validated terrain and obstacle data from government agencies, other authoritative sources and "non-authoritative” public and private sources. The report cites the company as saying, “Honeywell’s selected terrain and obstacle source data do not include Black Rock.”

The report says the helicopter, operated by CHC for the Irish Coast Guard, was in stable, level flight at 200 feet radio altitude, flying at 75 kt indicated on an approximate heading of 120 deg magnetic when the cockpit voice recorder captured a crewmember in the rear cabin reporting "an island just in, directly ahead of us now, guys. You want to come right.”

The aircraft commander asked to confirm that, according to the CVR, and the crewmember replied, "Twenty degrees right, yeah.”

About five seconds later, the CVR captures the crewmember saying, “Come right now come right COME RIGHT,” the report says.

In the final seconds, the report notes, the helicopter “pitched up rapidly, impacted with terrain at the western end of Black Rock and departed from controlled flight.”

The CHC aircraft commander, co-pilot, winch operator and winchman all died as result of the crash. The investigation is ongoing.

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