A Boeing with 139 people on board landed on a runway closed for repairs at Calcutta airport on Monday, screeching to a halt just 800 metres short of where men and machine were at work.

A dozen workers, supervisors and engineers stationed near taxiway C of the primary runway ran for their lives as the SpiceJet flight from Bagdogra hurtled towards them at 250kmph after landing on the northern end at 2.46pm.

Fortunately for the workers and everyone on board, the pilots spotted three jeeps and a painting machine on the runway and used the “special-mechanism brakes” to stop the aircraft from ramming into them.

“A disaster would have been inevitable had the emergency brakes not been used. It was a very close shave,” a runway engineer said.

Neither Air Traffic Control nor SpiceJet would say whether the plane landed on the wrong runway because of pilot error or a communication gap. One of the pilots of the Boeing 737-800 was a foreigner.

“Radar records will have to be scanned to find out what led the pilots to land the plane on the closed primary runway instead of the secondary one,” an official of the Airports Authority of India said.

When a runway is closed for maintenance, the path-indicator lights on either flank are switched off to avoid confusion. “Not a single light along the primary runway was on. Besides, we had issued a Notam (notice to airmen) on the closure of the primary runway from 1.15pm to 3.15pm on Monday,” the official said.

The directorate-general of civil aviation has started an inquiry into the incident.

In their statements to the airport authorities, the pilots of the aircraft said they didn’t know how the error occurred.

“The duo told us that they realised their mistake at the last moment. It was too late to abort the landing,” said one of the officials who spoke to them.

Netaji Subhas Chandra Bose International Airport has been in the news for the wrong reasons in recent months. Complaints range from poor maintenance of facilities to jackals and stray dogs loitering on the runway, forcing approaching aircraft to hover over the airport.