What went wrong in Midtown crane accident?

MIDTOWN (WABC) -- The massive boom crane still stands seemingly undamaged by the morning accident, offering few visible clues as to what went wrong.

"From what I can tell the crane was in good working order. We do track all cranes in the city," says the Commissioner Department of Buildings, Rick Chandler.

On any given day, around 300 cranes are operating in the city. The one in Sunday's accident is a mobile hydraulic crane owned by Bay Crane of Long Island City. It's still unclear what caused the 4-ton air-conditioning unit to drop, possibly a bad hoisting cable or human error when moving the massive unit through the opening on the 29th floor.

In 2008, a crane collapsed on East 51st street after slings lifting a heavy piece of equipment failed. Seven people were killed in what remains the city's deadliest crane accident. That led to city to adopt stricter regulations including more crane inspections, tougher licensing requirements and training for crane operators and taking old cranes out-of-service.

"There is no real oversight. There are not enough people in the field. Not enough follow up," said Construction Safety Attorney Susan Karten.

A 2013 Eyewitness News Investigation revealed despite the city's crack-down many crane operators continue cutting corners. Records that showed a crane nearly tipping over, putting the risk of workers hurt or killed extremely high. Eyewitness News uncovered numerous violations for operating without a license, and using defective equipment.

Just last month, a worker was crushed to death on the East Side when the boom arm of a crane collapsed on him. In Sunday's accident there were no serious injuries but it is raising concerns that once again city safety oversight is having trouble keeping up with another building boom.

"We think this device is in good shape, and we will follow up with that and find out why this load was dropped inappropriately," said Chandler.