Investigators have scoured the slopes of a ravine in southern India looking for the black box of a Boeing 737-800 that crashed off a hilltop runway, killing 158 people.

Crash site experts sifted through the wreckage and collected some parts, but were still to find the flight data recorder which could provide clues about Saturday's crash.

The Air India Express flight carrying 166 people crashed while negotiating a tricky landing at Mangalore city's "table-top" airport overlooking a ravine.

Eight people survived, mostly by jumping out of the plane that broke into two after crashing.

About a dozen aviation experts were seen examining the jet's mangled hull. At a distance, workers used bulldozers and metal-cutters to clear debris. Though it was not clear what caused the crash, some Indian TV channels focused on the possibility of human error.

India has seen a boom in private carriers due to growing demand from India's middle class. It was the first big crash in more than a decade but a series of near misses at airports, including Delhi and Mumbai, have caused concern India's creaking infrastructure was failing to keep pace with an economic boom.

Officials said all 158 bodies had been found.

All the passengers were Indian nationals, an Air India official said. Many were likely to be migrant workers in Dubai, the rich Gulf emirate which employees thousands of men and women for poorer Asian countries, often to fill lowly jobs.