Missing helicopter: Police launch Snowdonia ground search
A land search is under way to try to find a helicopter carrying five people which went missing over north Wales.
North Wales Police is coordinating the search in Snowdonia with the Coastguard and other agencies.
UK Coastguard duty commander Mark Rodaway said seven mountain rescue teams and a dog unit were involved in the search with visibility "improving".
The privately-owned helicopter vanished while over Caernarfon Bay en route to Dublin from Luton.
Radar contact with the red Twin Squirrel helicopter was lost on Wednesday afternoon and initial searches followed the intended flight plan of the aircraft over the Irish Sea.
Supt Gareth Evans of North Wales Police said "All available police, mountain rescue and other civilian resources are currently being utilised and we are grateful for the assistance and cooperation of the public as well as our MRT volunteers who are searching very difficult and challenging terrain."
Supt Evans said family members of those on board had been contacted by police, but their names have not been released.
Mountain rescue teams and an ambulance are currently at site next to Trawsfynydd lake in Gwynedd and police have closed a road, but it has not been confirmed if this is related to the search.
Mr Rodaway said: "These aircraft normally carry beacons that we can track by satellite - they're activated by salt water - we've not seen any of that and also mobile phone data has aided our inquiries in shifting inland."
Helicopter searches between north Wales and the shore of Dublin on Wednesday were scuppered by low lying cloud, which reduced visibility.
However, Mr Rodaway told the Jason Mohammad Programme at 10:50 BST "things have improved", after visibility had been as low as just 10ft (3m) in places.
"We are now able to commit more aircraft into this live search operation," he added.
A Mayday broadcast has been issued to all vessels passing through the Irish Sea to contact the Coastguard if they see anything.
The Eurocopter AS355 Ecureuil 2 (Twin Squirrel), made by Airbus, has a cruising speed of 140mph (225km/h) and a range of nearly 440 miles (700km).