GRAND MANAN, N.B. -- An air ambulance crash in New Brunswick that killed two people and injured two others occurred during the pilot's second attempt to land, says the Transportation Safety Board.

In an interview Monday, Michael Cunningham, the Atlantic regional manager for aviation investigations, said the early stage of the investigation is focusing on conditions at the time of Saturday's crash on Grand Manan Island.

Cunningham said it was dark and there was fog in the area, which may have contributed to the pilot making a second attempt at landing after an initial approach.

"The fact that they did a missed approach the first time around would suggest the visual conditions at the time were challenging," said Cunningham.

The crash, which occurred at about 5 a.m., killed Atlantic Charters airlines pilot and company president Klaus Sonnenberg along with paramedic William Mallock of Grand Manan. Another pilot and a nurse who were on board survived.

Cunningham said investigators had not found any indication of mechanical failure with the twin engine Piper PA-31 Navajo, but still aren't ruling anything out.

He said a technical and an operations investigator were conducting interviews and aircraft components would be removed for analysis by the safety board's engineering lab in Ottawa.

Cunningham said the aircraft's global positioning system would be of particular interest because the plane doesn't come equipped with a flight or voice recorder. He said Grand Manan also isn't covered by flight radar based in Moncton, N.B.

"There are memory chips in them (GPS) and hopefully that will give us some data about the approaches themselves."

Atlantic Charters said Monday that it would resume operations immediately.

The move was welcomed in a statement by Paul Ward, interim president at Ambulance New Brunswick, who said alternate transportation arrangements had been made with the province to assist island residents in case of medical emergencies.

"I know Atlantic Charters was anxious to resume its operations," said Ward. "Ambulance New Brunswick supports their decision."