Sixteen air crashes claimed 555 lives last year, the worst year for fatal airline crashes since 2014.

The worst was the loss of the Lion Air Boeing 737 MAX which crashed on October 29 after take-off from Jakarta, killing all 189 people aboard.

Preliminary reports suggest the accident was caused by a faulty calibration of an angle-of-attack vane which was replaced just before the fatal flight.

In 2014, the downward trend in plane crash deaths was given a tragic jolt by the loss of two Malaysia Airlines 777s with a combined death toll of 537.

Despite the higher number of deaths last year the accident rate continues to decline overall, with 4.5 billion passengers travelling on 45 million flights last year.

That translates into a fatal accident rate of one every 2.8 million flights.

And for airlines that have passed the International Air Transport Association’s operational safety audit, the fatal accident rate improves about 75 per cent.

Indonesia’s national transport safety committee’s preliminary report said that Lion Air put the 737 involved in the crash back into service despite problems with the plane on earlier flights.

It said the Lion Air 737 was not airworthy and should have been grounded.

The national transport safety committee said that an angle-of-attack vane which was replaced, because it was faulty, was not correctly calibrated.

After take-off, the angle-of-attack vane gave the captain flying the 737 incorrect data and caused what is called a “runaway stabiliser trim”.

This is caused by the plane’s computers incorrectly sensing the aircraft is going to have an aerodynamic stall and it compensates by pushing the nose down through the stabiliser trim system.

With continual incorrect data feeding into the aircraft’s computers the nose-down force from the stabiliser trim continues.

This happened on the previous flight and the pilots correctly flicked two switches to disconnect the trim system, continued their flight and reported the problem.

However, on the fatal flight the pilots did not do this.

The Indonesian national transport safety committee is yet to find the plane’s cockpit voice recorder which will shed light on what other issues the pilots may have faced.

The other major crashes last year involved airlines that were either banned from Europe or operating ageing aircraft, and none of these operators, with the exception of Air Niugini, which lost one passenger, had completed the IOSA audit.