Air India Express B-737 taxying on a rainy night ended up in a drain at Kochi airport in southern state of India. How could this have happened? For every, occurrence/behaviour there is a reason. Besides fatigue, environment, poor taxi markings, the reason for this occurrence could have been the intermediate taxi holding marking.

The pilot was instructed to turn left on taxiway “F” and hold short of taxiway “L”. The picture above is a view from taxiway ‘C’.

The fatigued crew was taxying at night on a taxiway with standing water. The instruction was to turn left onto ‘F’. It was the last leg of the flight. The co-pilot was over cautious. She suggested that the aircraft be taxied very slowly since the ground markings were not clear at the parking position which was stand 23L.

The aircraft taxied on ‘C’ and after crossing ‘E’ would have turned left on to ‘F’. However, the aircraft turned left before reaching ‘F’ and entered the drain parallel north of taxiway ‘C’.

What led the Pilot to take a turn before reaching the taxiway could not be determined by the investigation report.http://dgca.nic.in/accident/reports/VT-AYB.pdf

In the sea of blue lights and wet surface, the markings on the ground are extremely difficult to establish. This coupled with the fact that the crew were on their last leg of duty in the circadian low period could have misled the pilot. In all likelihood the pilot would have assumed or mistaken the intermediate taxi holding line which runs across the taxiway as the leading in line for taxiway ‘F’. The final position of the aircraft is in line with the same line.

The final resting position.

The report quotes the co-pilot as saying the following “Co-pilot also requested PIC who was at controls, to go slow as runway markings were not visible and advised to call follow me jeep. However, there was no response from PIC.”

CVR transcript” At time 210939, Co-Pilot said ( to PIC) “Sir, go extremely slow because the runway mark at the marking over there might not be seen. So then we might have to call for follow me. Because that 2, 3 left and right”.”

This seems to be misquoted since the co-pilot was referring to stand 23L where the markings were poor. There are 3 stands 23, 23L & 23R. It is also true that the taxiway centreline markings on ‘C’ were poor but this could have added to the confusion.

Read my paper on conformist factor.