Causes and risks.
Another TSB report of dubious quality in identifying the causes of a near catastrophe. Leaving aside the organisational failures to recognise the seriousness of this event, and the consequent loss of data which would devalue any report, the bottom line here is that the aircraft deviated very dangerously from the desired flight path below DH/MDA with neither pilot recognising it, but the report contains nothing to avoid such events in future.
The report only outlines how this deviation might have happened, but doesn't provide an answer to why. IMHO it is the combination of inadequate crew coordination procedures and Transport Canada's failure to adhere to ICAO SARPs in respect of required visual reference to continue an approach - identical to Air Canada's near catastrophe at Halifax in 2014.
ICAO Annex 6 requires the pilot landing to have visual references that have already confirmed the flight path is correct before leaving DH/MDA. Canada only requires that cues "enable" an assessment of it (report 1.18.2) - you can take as long as you like doing it, and may come to the conclusion that it's unsatisfactory. Which is what happened on reaching runway level at Halifax, resulting a crash that wrote off the aircraft. In this case it was at 40ft, and only after the second GPWS warning.
Here, incorrect identification of the cues at MDA, combined with the EXPECTATION of improvement, led the First Officer to wrongly assess the flight path. In his mind it now needed a correction, which de-stabilised the approach both laterally and vertically.
The difficulties of making this type of assessment are well described in 1.18.3, so no-one can claim that it's not a long recognised risk. Crew procedures that involve both pilots in the visual assessment inevitably make the situation worse, by deliberately exposing two pilots to the same risk of using inadequate visual cues, while perfectly valid instrument information slips out of sight and out of mind.
Also in this case, these problems were probably exacerbated by the fact that it was the F/O's leg. As being able to land had now become questionable, the Captain was likely concerned that the F/O's decision was in fact the correct one, causing his instrument monitoring to drop even further down his mental priority list. Result : 2 pilots head up, trying to make sense of the visual picture, and no-one registering that the flight path was into the water.
But unfortunately you can't rely on getting that sort of analysis in a TSB report. Notably, the "findings as to risk" look only at the consequences of (1) not implementing ICAO PANS-OPS regarding light settings, and (2) crew not identifying and managing threats. How about a few others?
"If Transport Canada regulations do not clearly identify that the pilot's visual references must have allowed him or her to complete an assessment of the aircraft position and rate of change of position before descending below an MDA or DH for a manual landing, as required by ICAO Annex 6, there is a risk that the assessment will not be completed in time to avoid impact with obstacles."
"If airline crew procedures are not based on a plan that the pilot flying the approach will execute a missed approach at DH/MDA unless the pilot landing has made a positive announcement that the aircraft's position and rate of change of position are suitable for continued approach, there is a risk that plan continuation bias will result in descent below DH/MDA without adequate visual cues to avoid obstacles or complete a safe landing."
"If crew procedures involve the pilot NOT intending to make the landing making visual assessments prior to, and/or on behalf of, the pilot who IS intending to make the landing doing so, there is an increased risk of a hazardous plan continuation bias."
"If crew procedures do not ensure that there is continuous instrument monitoring from the FAF until landing, there is a risk that essential instrument information and warnings will go unnoticed. "
"If the wording of crew procedures that require an exchange of instrument monitoring obligations does not specifically require announcement of exchanged tasks, there is a risk that instrument monitoring will not be continuous and essential instrument information and warnings will go unnoticed. "
"If procedural callouts alerting the pilot to arrival at DH/MDA (and the end of the decision process) are phrased as advisory (e.g. "minimums") rather than imperative (e.g. "Decide!") they risk being ineffective as salient triggers, allowing inadvertent descent without adequate visual reference."
Just a thought.....