In two separate incidents, the year 9 boys, who were on a 10-day hiking trip, got lost in the wilderness of the Walls of Jerusalem National Park.

Tasmania's Deloraine police Inspector Darren Hopkins told a Fairfax newspaper in Tasmania the school would need to improve emergency procedures before venturing into the area's wilderness again.

"There are certainly a couple of lessons to be learnt for the school," he said. "They had poor procedures in place between the teams themselves to ensure they stayed together."

The boys were among 50 students on a resilience training camp, accompanied by 15 adults and several teachers.

Teachers waited 24 hours before calling police when the three 15-year-old boys went missing at 2pm, Wednesday, two weeks ago.

Another student, Tuong Pham, 14, was reported missing within four hours the following Monday after he became separated from his school group in the park.

A large-scale search for the boy began. It involved two helicopters and, on the ground, police and search and rescue volunteers.

Tuong was found the following morning.

Inspector Hopkins said he had held grave concerns for the student's safety.

He said the teen was lucky to have survived the harsh conditions overnight and he had doubts he would have lasted much longer.

"His condition was deteriorating when he was found. I don't think he would have survived another night in similar conditions."

Tuong's walking group of 10 had split into three groups and, due to delays in his group, Tuong decided to attempt to catch up to the group walking ahead.

The school's principal, Mark Vodell, said he would review the resilience training program for year 9 students.

Teachers decided to wait 24 hours before contacting police because they knew the three boys were safe as they had good equipment, food and training to cope in such area, he added.