CHC, Bristow and Bond helicopters halt some flights after ditching
All three operators of North Sea offshore helicopters have grounded the type of aircraft involved in Monday's ditching off Shetland.
A Super Puma EC 225, operated by CHC, carried out a controlled landing close to Fair Isle. All 19 people on board were rescued safely.
CHC said it was suspending operations using helicopters of the same type.
Bristow and Bond have now also delayed operations of EC 225 and L2 Super Pumas, during the investigation.
The Unite union said there was a growing fear among offshore workers over helicopter safety.
Unite industrial officer John Taylor said: "Mercifully there were no fatalities with this latest incident."
The manufacturer, Eurocopter, said it had full confidence in the aircraft.
A spokesman for Bristow Helicopters said: "The safety of our passengers and crew is of paramount importance to Bristow and we comply fully with the manufacturer's recommended maintenance and operational procedures for all of our aircraft."
A Bond spokesman added: "As a leading provider of mission critical services Bond Offshore Helicopters is committed to the highest standards of airworthiness, with the safety of our passengers and crew being our highest priority."
Shetland Coastguard said the CHC Super Puma involved in the ditching was still floating on the surface of the sea near Fair Isle, about 30 miles south of Shetland.
The emergency tug, Herakles, attached a line to the helicopter, to protect the aircraft from the swell, and coastguards have been broadcasting hourly navigational warnings to nearby shipping.
An oil supply vessel, Olympic Zeus, has sailed to the scene. The plan is to lift the helicopter onto the deck of the vessel.
The ditching will be investigated by CHC, the Air Accidents Investigation Branch (AAIB) and Eurocopter, which is sending a specialist team to Aberdeen.
The helicopter had been heading to the West Phoenix drilling rig, west of Shetland, when the alarm was raised at about 15:30 on Monday.
Passengers have praised the pilots for the way they handled the incident.
Michael Mashford, one of those onboard, said: "It's strange because yes, I was afraid, but all the training that we do kicked in.
"Everybody was very very calm. One of the guys that's normally one of our rescue guys, he's very cool, calm and collected and he kept people calm and we did everything that's expected of us.
"We all got into the rafts, got away from the helicopter. No problems at all."
Nick Mair, regional vice president of western North Sea at CHC, said: "Plans are under way for the recovery of the aircraft.
"We are temporarily holding flights using the same type of EC 225 aircraft pending receipt or confirmation of certain information from the crew involved in today's incident and technical follow-up."
In May, all 14 people on board a Super Puma EC 225 were rescued when their helicopter came down around 30 miles off the coast of Aberdeen during a flight to an oil rig.
Jake Molloy, from the RMT union, said the latest ditching was "bound to cause a bit of concern on the ground".
He added: "I think what's absolutely vital now is to get communications out to reassure the workforce and their families, that their means of transportation to and from their work is safe."