The search for a helicopter missing with five people on board is now focusing on the Snowdonia National Park.
The privately-owned Twin Squirrel aircraft is believed to have left Milton Keynes to fly to Dublin, via Caernarfon Bay, before disappearing on Wednesday afternoon.
An extensive search of the Irish Sea and Snowdonia was launched at around 4.15pm on Wednesday after the Distress and Diversion system lost radar contact with the helicopter.
The search was scaled back overnight due to poor weather conditions but North Wales Police and mountain rescue teams are continuing to search on the ground.
Coastguard commander Mark Rodaway told BBC Breakfast the focus for the search had shifted inland.
He said seven mountain rescue teams and a dog search team were involved in trying to find the missing helicopter.
He said: "There's a whole range of inquiries that we will engage with; first of all we're working very closely with air traffic control and we're looking at a review of radar information and, secondly, obviously we will look for mobile phone data.
"All of that combined has given us a new focus, in and around the Snowdonia National Park."
Two UK Coastguard search and rescue helicopters based at Caernarfon and St Athan were scrambled to scan the area between Caernarfon Bay and the Dublin shore on Wednesday, with all vessels on the Irish Sea route at the time also asked to report sightings.
On Thursday a Coastguard spokeswoman said "air assets" would not be able to resume the search until weather conditions improved.
She said: "We've had some reports of less than 10 metres visibility in areas so the search teams really are being hampered by poor weather conditions.
"No air assets have been sent out by the Coastguard.
"That said, we are still looking to support North Wales Police in any way we can.
"We will do that when the weather provides us with that opportunity."
A police spokesman said: "North Wales Police are co-ordinating ground searches with mountain rescue teams and working with the Coastguard and the Aeronautical Rescue Co-ordination Centre (ARCC)."
The Eurocopter AS55 Ecureuil 2 (Twin Squirrel), now made by Airbus, is a widely used twin-engine light utility helicopter which has a reputation for durability and requiring low maintenance.
First introduced in the mid-1970s, the all-weather aircraft has evolved through several variants and is used by both civil and military applications.
With a cruising speed of 140mph and a range of nearly 440 miles, the model is used for extended low-level flights involved in filming and surveying.
Champion rally driver Colin McCrae was at the controls of a Twin Squirrel with his five-year-old son Johnny and his friend Ben Porcelli, six, on board in 2007 when it crashed in the grounds of his Lanarkshire home, killing all three.