One month after four children vanished into the Colombian Amazon, a preliminary report by the country's Civil Aviation Authority offers clues to how they could have survived the devastating airplane crash that killed every adult onboard.

The extraordinary story of the missing children has drawn intense interest across Colombia and internationally, as a massive military-led search operation continues in the forest.

The ill-fated flight on May 1 carried pilot Hernando Murcia Morales, Yarupari indigenous leader Herman Mendoza Hernández, an indigenous woman named Magdalena Mucutuy Valencia, and her four children, the eldest 13 years old and youngest just 11 months.

Soon after the early morning take-off from the remote community of Araracuara, the pilot radioed to air traffic control that he would look for an emergency landing spot, according to the report.

"...Mayday, Mayday, Mayday, 2803, Mayday, Mayday, Mayday, I have the engine at minimum, I'm going to look for a field," he said.

The pilot later updated that the engine had regained power, and continued on his way -- only to hit trouble again less than an hour later: "...Mayday, Mayday, Mayday, 2803, 2803, The engine failed me again... I am going to look for a river... I have a river on the right..."

This time the problem did not improve.

Air traffic control later tracked the plane veering right, the report said. Then it went off the radar.

Despite air and water searches that immediately followed the incident, per the report, the plane would not be found until more than two weeks later -- time that may yet prove significant in the fates of the plane's passengers, as investigators continue to probe the crash and its aftermath.

A crucial seat map

Five days after the plane's disappearance, the Colombian military deployed special forces units to search the ground on May 6. Ten days later, on the night of May 16, they finally spotted the wreckage.

The three adults were found dead at the scene. But all four children were missing entirely -- leading rescuers to presume that they had survived, evacuated the plane and were trekking the jungle on their own, and spurring a renewed search effort.

Investigators' photos of the crash scene show the raised tail of a small plane painted in still-crisp blue and white, its nose and front smashed into the jungle terrain. The report says the plane likely first hit the trees of the dense forest, tearing the engine and propeller off, followed by a vertical drop to the forest floor.

"Detailed inspection of the wreckage indicated that, during tree landing, there was a first impact against the trees; this blow caused the separation of the engine with its cover and propeller from the aircraft structure," the report says. "Due to the strong deceleration and loss of control in the first impact, the aircraft fell vertically and collided with the ground."

Though it notes that forensic examinations are ongoing, the report suggests that the adults seated in the front of the plane cabin suffered fatal injuries from the crash. "The diagram of injuries caused by the accident registered fatal injuries in the occupants located in positions 1 (Pilot), 2 (male adult occupant) and 3 (female adult occupant).

But the rear seats, where the older children were located, were less affected by the impact, according to the report, offering a potential explanation for their survival and signs of life -- including a baby bottle, a used diaper, and footprints -- later found in the jungle by search and rescue teams.

Two of three seats occupied by the children remained in place and upright despite the crash, according to the report, while one child's seat came loose from the plane structure.

The infant may have been held in the mother's arms, according to the report.

The children "were not located in the area of the accident, and there were no signs that they had been injured, at least not seriously. For this reason, an intense search began in order to find them," it says.

A total of 119 Colombian special forces troops and 73 indigenous scouts have so far been deployed to comb the area, according to the report.

Relatives have previously said that the children knew the jungle well -- but worried whether they would understand that the outside world had not given up on them.

"Maybe they are hiding," said Fidencio Valencia, the children's grandfather, speaking to Colombia's Caracol TV earlier this month.

"Maybe they don't realize that they are looking for them; they are children."