Updated

The Brazilian navy on Sunday defended its response to a shipwreck that left dozens of teenage students from around the world adrift on the ocean for two nights.

The navy deployed a search aircraft about 19 hours after it received a distress signal from the SV Concordia on Wednesday, which officials say is in line with standard procedure.

All 48 students and 16 crew members were safely rescued Friday, nearly 40 hours after the sailing ship capsized in the Atlantic several hundred miles off the Brazilian coast.

The students, who were taking part in the Canadian-based Class Afloat program, were expected to begin flying home later Sunday as soon as their emergency documents and plane tickets were arranged.

Nigel McCarthy, president and CEO of West Island College International of Lunenburg, Nova Scotia, which operates Class Afloat, expressed concern that the students were left adrift on life rafts for so long before being rescued.

"We're certainly trying to gain a better understanding of why does it seem like such a long time," McCarthy told The Associated Press on Sunday. "We really don't know. These are the same people, of course, that we're thanking for bringing home our kids so we have to be attentive."

Navy spokeswoman Maria Padilha said that naval responders received a distress signal about 8 p.m. Wednesday and immediately tried to make radio contact with the vessel. They also communicated with nearby ships and aircraft to see if they could spot anything wrong in the area, Padilha said.

The aim was to assess what type of emergency had occurred, she said, given that it could have been anything from a minor engine problem to a grave illness or a sinking ship.

The ship's captain, William Curry, has said that the vessel capsized Wednesday afternoon. It was not clear why the navy did not receive the distress signal until hours later. McCarthy said Saturday that the London-based Barbados Maritime Ship Registry, which works on behalf of the government of Barbados, will conduct an investigation.

When their efforts to communicate with the SV Concordia failed, Brazilian naval authorities reached out to school officials in Canada — but not until about 10 a.m. Thursday. The officials also had no luck getting the ship's captain and crew on the radio or through e-mails, prompting the navy to ask for an air force search operation in the general location of the distress signal.

An aircraft left about 5 p.m. local time and about three hours later spotted the students and crew on rafts 300 miles off the coast.

Navy Lt. Edward Stansfield, public affairs officer for the Canadian Maritime Forces Atlantic, said the policy of the Joint Rescue Co-ordination Centre in Halifax is to send planes immediately after receiving a distress signal from any ships offshore.

If the agency had received a distress signal from a Brazilian ship "in our waters here, that's exactly what would have happened," Stansfield said.

Curry said the three-masted Concordia apparently experienced a weather phenomenon known as a "microburst" — a sudden, violent downdraft of wind — that instantly crippled the vessel.

School officials said 42 of those aboard were from Canada, while others hail from the United States, Australia, New Zealand, Mexico, Europe and the West Indies.

Kate Knight, head of the West Island College, said that by Tuesday all students would be on their way home.

McCarthy said the survivors spent most of Saturday replacing items that went down with the ship and also had meetings with trauma counselors and medical personnel.

All that remains at this point, he said, is to get the students "into the arms of their parents as quickly as we can."