9.40pm, Monday, March 13th

The Irish Coast Guard’s rescue co-ordination centre at Malin Head receives a call from a UK registered fishing vessel off the Mayo coast to say one of their crew members had been injured.

As the incident has taken place 241km (150 miles) off the coast, the Coast Guard sends out two helicopters. The Sligo helicopter is sent out to pick up the injured crewman while a Dublin based helicopter is also sent out “in chase” as a backup for the Sligo aircraft and to assist with communications.

Having travelled from Dublin across the mainland, the Dublin-based Sikorsky S-92 helicopter, known as Rescue 116, must stop to refuel at Blacksod before continuing to assist with the rescue.

12.45am, Tuesday, March 14th

The Coast Guard receives the final message from the Dublin helicopter - Rescue 116 - to say it is making its approach to Blacksod to refuel before heading out into the Atlantic.

The Coast Guard has been tracking the helicopter and becomes concerned when it disappears from their screen. The Coast Guard carries out a communications search and then declares a “mayday”. Conditions at the time are described as rough with poor visibility but still considered “fine for flying”.

The Coast Guard calls on the RNLI Ballyglas and Achill lifeboats to take part in the search and rescue operation. The Shannon helicopter is also sent out to scan the water, while the Air Corps and Naval Service arrive at the scene to take part in the search. Five fishing vessels in the area also respond to the mayday call and are involved in the search.

1am, Tuesday, March 14th

Air Accident Investigation Unit (AAIU) receives an alert from air traffic control that an aircraft has gone missing. Mr Juergen Whyte, chief aeronautical officer with the AAIU makes contact with investigators and within one hour, a team of two investigators are en–route to the area where the helicopter went missing.

2-2.30am, Tuesday, March 14th

After completing the medical evacuation of the injured fisherman, the Sligo helicopter arrives at the area where Rescue 116 went missing and spots wreckage in the water about 2.5km (1.5 miles) southeast of Blackrock lighthouse, about 8km (five miles) offshore from Blacksod.

Daybreak, Tuesday, March 14th

Shortly before daybreak, one of the crewmen is spotted by the Shannon-based Sikorsky S-92 helicopter and picked up by an Achill-based lifeboat near the Blackrock Lighthouse. The crewman is in a “critical condition”.

9am, Tuesday, March 14th

The search and rescue efforts are continuing in what the Irish Coast Guard has described as “good visibility”. However, Irish Coast Guard acting director Eugene Clonan says he is “not holding out much hope” for the rescued crew member or the missing crew.

Shortly after 3pm on Tuesday, March 14th

The Irish Coast Guard confirms that one of its most senior pilots, Capt Dara Fitzpatrick, died when the Dublin-based helicopter crashed off the Mayo coast in the early hours of Tuesday morning. Capt Fitzpatrick was pronounced dead in hospital after she was taken from the sea by the RNLI Achill lifeboat and transferred to one of the two Irish Coast Guard helicopters involved in the ongoing search.

Tuesday afternoon, March 14th

An extensive search continues off the Mayo coast for the three missing crew while further wreckage from the aircraft is brought ashore. A Norwegian salmon transporter also assists in the search.

What’s next?

The Coast Guard and AAIU have said the first priority is to carry out a thorough search and rescue operation for the remaining three crew members from the missing helicopter. Following that, the search will begin for the aircraft’s wreckage in the hopes of finding the two recorders from inside the helicopter. One of the recorders will have a record of all voice communication while the second will provide data on the level of power from the aircraft’s engine, its speed and its height.

If recovered, the recorders will be used to analyse the flight and recreate a digital flight to help investigators determine what happened in the final moments of the flight.