I am with PEI, I don't think anyone should just attribute this to "lack of discipline" and "busting minima". There's no real evidence of that IMO.
However it has become clear from my own reading of about 120 reports of approach accidents over the last 25 years that a very common factor (as in this case), is when valid instrument information is discarded prematurely in favour of dubious or inadequate visual cues. This is very frequently associated with an expectation that things can only get better, when in fact it doesn't .
There MAY be cultural / psychology elements contributing to some of these. For example in the current case we have two extremely experienced (14,000 and 12,500 hours) Canadian pilots who are used to "real" bad weather. Surely a few Caribbean shower clouds are not going to be a big deal for them. Nevertheless, being professionals they prepared for an instrument approach anyway. On the way in, they know about the shower clouds, but NOT that the visibility has now gone below minimum. Would it have been prudent to ask? Would that imply acknowledging that getting in might actually be questionable - "don't ask, don't tell"? I emphasise I'm only speculating here. In any case visibility minima don't guarantee that sufficient visual reference WILL be available at DH/MDA, only that it's reasonably likely, and there's no evidence of this crew deliberately ignoring minima.
But in this case, just prior to reaching the MAP both pilots seem to have switched to using the very poor visual references as their primary guidance. Quote from the report: "given that THEY [plural] had the shoreline in sight and expected to see the runway shortly afterward, they would continue the approach visually." So the F/O must have been at least peripherally aware that some visual cues exist, and now concentrated on identifying anything that looks appropriate as being the "right" cues. He must have been sure he was looking at the "runway" within 1/2 mile of the MAP because he disconnected the autopilot and then pitched down. Pitch down is a known instinctive reaction to a reducing visual segment or to distortion caused by rain on the windshield. The 50% increase in descent rate caused the autothrust to reduce, following which it was disconnected and apparently stayed at 52% until the eventual go-around. Then, "As the crew crossed MAPON, the PF advised that he had the runway in sight. He began to roll left."
Just after the MAP they entered a heavy shower and were subject to much reduced visibility for about 20 seconds. Even though the aircraft track was maintained towards the "runway" (actually the hotel), the vertical path was significantly steeper than it should have been, with no means of detecting this visually, because since the "runway" wasn't one it obviously wouldn't give the necessary cues. On leaving the shower, the dominant feature was the lateral asymmetry of the runway being off to the right, so that was the instinctive priority to correct.
Understanding the new visual picture is such a compelling and demanding task that with no approach lights, limited runway lighting and no surface texture, the vertical displacement and rate was so much harder to detect that it was still not fully recognised. The F/O increased thrust from 52% to 75% as he made the first correcting turn, but that did not bring the RoD back to the correct value, let alone regain the correct descent path. Even after the first GPWS alert there was only a partial understanding of the situation, and a full realisation and response is delayed until after the second warning 9 seconds later.
In my opinion this crew were persuaded to become mentally committed to landing by two things: sight of the absolute minimum of appropriate information at the MAP, and the expectation that this would increase. This expectation was based on their own experience that usually it does, and reinforced by the report from the previous landing aircraft. Having made this decision, they were simply unable to reverse it until forcibly reminded by a totally independent external stimulus - the GPWS.
Human nature is such that when exposed to such a visual puzzle it is extremely easy to become absorbed in it to the exclusion of other things, and no amount of exhortation about emphasising cross-monitoring of instruments etc. is going to change it. There's nothing cultural or ill-disciplined about it. To me, this sort of thing is a compelling reason NOT to deliberately expose both pilots to the same potential problem.
But regarding "sight of the absolute minimum of appropriate information" there may also be a specifically Canadian issue. I think Canada's rules, and by implication underlying training, may actually encourage this hazardous decision making. (It may be true elsewhere but I have no knowledge of that).
At some past date, someone must have made a specific decision that ICAO standards about what constitutes "adequate visual reference" to allow descent below DH/MDA were inappropriate for Canada. In my opinion the subsequent wording is much less conservative (i.e. less biased to the safe side).
The ICAO pilot's decision is "I've ALREADY seen enough to be sure of where we are and where we are going, and I can maintain a safe flight path using those listed elements - lights, markings, runway etc". (ICAO: The cues "should have been in view for sufficient time for the pilot to HAVE MADE an assessment of the aircraft position and rate of change of position in relation.... ").
Someone in Canada decided this should read : [the cues] "ENABLE the pilot to make an assessment of the aircraft position and rate of change of position...... ", followed by the CAP laundry list of items to be "distinctly visible and identifiable" including "the runway". Lawyers would doubtless have a field day about the difference but it seems to me that for practical purposes this can be interpreted as meaning "the runway being distinctly visible and identifiable at MDA enables you to make an assessment of position and flight path: consequently you may continue". Which rapidly becomes just "if I can see the runway at MDA I can continue".
Since these pilots clearly thought they HAD identified the runway (perhaps the "distinctly" visible is bit iffy!) they were not deliberately breaking any rules - any more than the AC crew at Halifax were by descending solely on the sight of the "rabbit" ODALS. Arguably, the Canadian rule is simply unsafe, since in essence it can be interpreted as allowing a look-see operation, which was never intended when the concept of DH was put into place.
Anyone Canadian AWOPs experts out there know the origin of this wording?