The Captain's decision to continue the approach below DH may have been affected by the fact that they had already held for 50 minutes awaiting weather improvement before attempting the first approach, following which the go-around had also been complex and time-consuming. Prior to the second approach a cabin crew member had told the Captain that a diversion might present some problems for them.

Circumstantial evidence indicated that the visibility had quickly and materially deteriorated from about the time landing clearance had been given. It was described by a domestic flight crew taxiing for departure at the time of the crash as "almost zero", a description supported by CCTV recordings and reports from military personnel located near to the threshold of runway 02.

The Investigation concluded that the visibility at the time of the accident had been 200 metres in fog - much worse than at the time of the earlier go around. It was noted that the deteriorating trend had not been communicated to the crew by TWR and neither had a SPECI for this change been issued by the Meteorological Office.

The report considered that the crew became fixated on landing.

• After the missed approach a member of the cabin crew had stated to the Captain their concern at the prospect of diverting to Delhi
• Immediately after this, the First Officer had told the Captain that the RNP approach would "bring them directly to the runway"
• Four seconds before the automatic annunciation of 'MINIMUM' the First Officer had said "it will appear if we descend below"
• There was no call of "visual" from PM who was required under SOP to look out for visual reference whilst the PF stayed on the instruments.
• Approximately 5 seconds before touchdown, the PF stated "appearing" - the first reference to the runway being in sight.

Below DH the crew did not have the visual references needed to detect that the autopilot (which was coupled to the mis-aligned RNAV path) was taking the aircraft off a safe flight path.  

Arrival at DH was marked only by an automated "minimums" call and neither pilot made the appropriate callouts to continue. Both were apparently focused on the external scene which gave little useful information as visibility was near zero.   

If PicMA had been the SOP, the factors that might have been affected include the following.  

1) The first approach, in conditions which were marginal but significantly better than the second, might have been successful as the Captain would have had more time to assess the developing visual cues. 

2) Prior to the second approach the Captain would have had more opportunity to consider the overall management of the flight, rather than the detailed flying of the complex missed approach procedure and the new approach in very challenging terrain (2nd source document). This would have included issues associated with the changing visibility conditions and a possible diversion.

3) A definitive "DECIDE" call would have been made by the First Officer at DH. As it was, both pilots made comments about visual cues around DH, but the relevant DECISION was not made. According to the report, "Four seconds before the “MINIMUMS” auto-callout, the F/O PM stated “it will appear when we descend below…”  and the Captain's response to the "Minimums" auto callout was "continue until 300ft." 

4) Even if the Captain had made the same inappropriate response to a DECIDE call, the F/O would have remained focused on instrument monitoring, not looking out. He would have registered the clear  "DISCONNECT AP FOR LANDING" annunciation on his PFD and any callout of this discrepancy would have alerted the Captain to the seriousness of the situation and probably triggered a go-around.     

PicMA would have reduced the likelihood of this event..