Originally Posted by
hans brinker
IMHO and not necessarily related, I always felt dive and drive appropriate for situations where the visibility was good, base above the MDA, and especially when doing non-straight-in approach. Anytime on a straight in approach in limited visibility a CDA approach is preferable.
Dive and Drive places the operation at risk of making a single sequencing error for a crossing height. Recall Katmandu's first Airbus accident etc, or Asianas loss in SW S Korea. A single error places you at high risk. Flying a continuous descent with an FMC giving VNAV guidance is generally much safer, In this particular approach however, if the FMC NDB throws up a fix height of the reduced minima at the MAP, then there is a potential for an unstabilised approach to result from that. Notwithstanding that setup, the crew are obliged to have visual reference at the MMA on a CDFA approach, and in this case would be required to have sufficient visibility to see the runway end. The evidence of the submerged aircraft hints that all was not well from that respect, or the crew were working on their seaplane ratings. If windshear wasn't involved, then the whole question of compliance with procedures will be the main center of investigation.
The pax are paying for the flight to be done in accordance with the procedures. If the procedures end up with diversions, that is what it is supposed to be. Making up rules as you go along is great until the wheels fall off the wagon, and people who are paying for a particular standard get left with the result. Normalisation of deviation hurts the flight crew as much as anyone else. They believe they are doing the right thing, and may accept deviations as they are achieving the outcome that the company wants from a short game commercial perspective. Playing the odds however will prove statistics in the end.
I hope that the data finds there was something else going on here, I really do, but cases of planes missing the airport is pretty untidy. Extenuating circumstances should include the design of the approach in this case, but once you go below MDA/DA, then the rest is up to the integrity of the flight crew complying with the requirements to continue a descent below MMA.
This is not meant as a criticism of the particular flight crew in this event, it is a sad lament on the number of events of this type that keep on keeping on, and which indicate that there is a level of normalisation that we as a collective group appear to not be mitigating fully. It is also not a regional or specific concern, it happens in Europe, in Indonesia, with a Canadian carrier in the Caribbean, and sundry other locations. Years ago, I pax'ed on a U.S. airline from LAX to YVR, a Boeing 3 holer, and we landed there in CAT IIIB conditions. I asked the crew afterwards when was their equipment upgraded to do such procedures, and they said it wasn't. Years later, at an airport that is only CAT I, in weather that was certainly CAT III, the aircraft that we were going to operate out, arrived. It was the only aircraft that did that morning, and they system just shrugged it's shoulders. Non compliance is a universal human trait.
The investigating bodies invariably allocate causation to "Pilot Error", I dispute that is really the basic cause; the pilots do not go out there intending to erroneously break the rules, the rules are being bent by the collective and the normalisation is resulting in the odd wild ride. We have seen one of these recently where the pilot's cognitive ability appears to have been impaired through emotional disruption, but otherwise, healthy crews have driven tubes carrying punters into the brine.
Descending towards water below minima without a runway threshold somewhere in the near future is not a perception error, either there is a runway out there that you are looking at a specific aiming point on, or there is not. Wave tops are poor aiming points.
A carrier if interested in ceasing non compliance could do so within days, but would be fighting the unions to do that, and I suspect that the status quo works out reasonably well for the airlines, their pax more often than not get to destination in these events with little or no awareness of the risks involved.
We can stop these events happening, but only if the profession acknowledges that the problem is us, and gets serious about ceasing the practice. I doubt that we have the will or interest in doing so, we naturally assume that the guys/girls who will get caught out are different to us, we do it better etc....