THE failure of search-and-rescue teams to locate the suspected, crashed Islander aircraft has raised questions about the effectiveness of a special piece of equipment designed to guide rescuers to aircraft crash sites – the Emergency Locator Transmitter (ELT).

ELTs are emergency transmitters that are carried aboard all aircraft.
In the event of an aircraft accident, these devices are designed to transmit a distress signal on 121.5, 243.0-megahertz frequencies (and for newer ELTs, on 406 MHz).
The ELT mandate resulted from the 1972 loss of U.S. Representative Hale Boggs and Nick Begich in Alaska after their aircraft crashed and was never found.
The ELT is a legal requirement for all aircraft operating in Guyana.
Commenting yesterday on the failed search to date, sources close to the aviation sector said the ELT on the Islander aircraft should have been activated on impact and should have been transmitting signals to search-and-rescue aircraft for at least 24 hours after the crash.
This would have enabled searchers to pinpoint the location of the crash relatively easily.
The functioning of the ELT on that particular aircraft however, remains shrouded in mystery and some amount of controversy.
The source added: “What needs to be determined is whether or not the ELT on that aircraft was transmitting on frequencies officially decommissioned at least five years ago; or whether the batteries had been fully charged or whether the equipment had been at the end of its shelf life.”
“There are more questions than answers,” the source said.
That source was however, quick to point out that the ELT signals could have been rendered inoperable if the transmitting antenna had been buried in the ground on impact or if the aircraft had ended up upside down.
He added that as far as he knew, the ELT of the Islander aircraft is located in the tail section to protect it from impact; but some things can happen to render it inoperable even in that spot.
He said that as far as he knew, it was precisely because of this that pilots are trained to turn on the ELT once a crash becomes unavoidable and before impact.
“They are trained to turn it on manually once it becomes evident that the aircraft is going down. We don’t know if the pilot did so, but he was trained to do so.”
He also pointed out that the inhospitable terrain can render an ELT inoperable.
“Dense forest; a crash site located at the bottom of a ravine can result in the same situation.”
But one source close to the sector said that a pilot travelling from Lethem to Ogle on that particular day had picked up signals from an ELT and reported same.
Another source questioned the accuracy of this, saying in the first place that the ELT normally works for at least 24 hours after a crash and so rescuers should have been able to zero in on these distress signals.
So even if the ELT on 8R-GHE had worked then, it would have worked only very briefly, since none of the rescue aircraft had been able to pick up these signals even though commencing operations within a 24-hour time frame.
At any rate, he said the pilot travelling from Lethem to Ogle should have been able to pinpoint the area from which the signals had been transmitted ; should have been able direct the search-and-rescue team to that general area and the search may have yielded results.
This apparently never happened.
Additionally, the sources said the ELT also works by automatically sending signals to orbiting satellites.
This information indicating a crash is relayed by the satellite or satellites to aviation officials of the United States.
They in turn relay the information to the local search-and-rescue teams, pinpointing the exact location of the crash and thus enabling recovery.
The source said that as far as he knew, no signals had been received from any satellite and accordingly no expert could have provided the information that would have been available had the ELT worked.
Another source said that the ELT frequencies used by some aircraft had been made redundant at least five years ago; hence, if that was the case in that particular aircraft, no signals would have been received.
“There are new frequencies. Had the equipment been updated?”
Another source argued that the ELT was not an exact science.
He said that there was a reported 50% failure rate of this equipment, especially old ones.
He expressed optimism that these issues will be fully addressed in the investigation into the disappearance of Air Services Limited (ASL) aircraft 8R-GHE and the inability to locate the crash site after more than two weeks of searches.
The aircraft transporting cargo from Mahdia to Karisparu, Region 8 (Potaro/Siparuni) disappeared around noon on December 28th last.
On board were captain, Nicky Persaud, 27, and cargo loader, Mr David Bisnauth, 51.
Up to yesterday, the crash site and their remains had not been located.

Meanwhile, the Guyana Civil Aviation Authority (GCAA) disclosed late yesterday that twenty-one Guyana Defence Force (GDF) Special Forces are currently combing through dense jungle and treacherous terrain in Region 8 in an ongoing effort to locate the Islander.
The ranks – in ‘three man’ teams – have been deployed to Muruwa and Siparuni River, two high interest areas, in search of the twin engine aircraft carrying pilot Nicky Persaud and loader David Bisnauth.
Apart from the Special Forces, eight Line Cutters from St. Cuthbert’s Mission, 10 Guyana Forestry Commission officers; six villagers from the Chenapau and five villagers from Karisparu have over time joined the search.
Extensive searches have been carried out in a large area between North Fork and Black Water rivers.
Two helicopters continue to execute aerial searches.

(By Clifford Stanley)