A woman who survived a jungle plane crash with her 1-year-old son drank coconut water to stay alive for four days until being rescued, Colombia's air force says.

Rescuers reached Maria Nelly Murillo and her child in a remote area of western Colombia and flew them to the nearby town of Quibdo for medical treatment on Wednesday. Murillo suffered some injuries and burns but the baby was unhurt.

They were aboard a twin-engine Cessna that crashed Saturday into the thick jungle shortly after taking flight from Quibdo, near the Pacific Ocean.

The pilot was killed, but rescuers said a load of fish on board absorbed much of the impact in the plane's cabin, allowing Murillo and her son to survive against the odds.

Murillo told rescuers she climbed a hill with her child to get away from the plane, which she feared might explode.

She said she survived on coconut water until a local person came across her on Tuesday and summoned help. Rescuers said they reached the plane two days after the crash, but found the two passengers missing.

They immediately called in reinforcements to launch a larger wider. They were aided by several clues left by Murillo, including a flip flop sandal, her son's birth certificate and the remains of eaten coconuts.

It's not clear why the plane, which was covering a local route between isolated communities in Colombia's western jungles, crashed.