Thanks Sarcs
The BOM submission has, at Table 2, what’s described as a “Chronology of key weather observations and forecasts at Norfolk Island for the period 0430-1130”. It summarises the observation/forecast rather than stating the ‘raw terms’.
The period from 07:39 to 09:30 confuses me bit:
07:39 – SPECI report – cloud base lowers below alternate minima – broken cloud 1100 feet.
08:03 – TAF amended; valid 0800 – 2400 to indicate below alternate minima cloud conditions – broken cloud at 1000 feet.
09:25-09:30 – SPECI reports – cloud base lowers further, visibility reduces due showers. Broken cloud 200-300 feet, visibility 4500m in showers.
Errrrm, what about the 0800 SPECI that said 9999 overcast at one thousand one hundred? That’s the one that, according to the ‘partial transcript’, was transmitted by Nadi and addressed to NGA. And why aren’t the 08:30, 08:56, 09:00 and 09:02 SPECIs mentioned in the Table either?
I guess BOM’s just trying to make the point that the cloud base lowered below the alternate minima at 0739, and therefore the other SPECI’s weren’t ‘key’ because they didn’t say the cloud base lifted above the alternate minima (until about 11:28)?
In any event, getting the WX info to NGA is not BOM’s responsibility, once the SPECI/METAR/TAF has been issued.
I suppose it now boils down to whether a different decision would have been made if the information in the cockpit had been:
0800Z AUTO 29008KT 9999 OVC011 21/19 Q1012 RMK RF00.0/000.0
0830Z AUTO 22007KT 9999 BKN003 OVC009 20/19 Q1013 RMK RF00.0/000.0
… with about 40 minutes to think about it and seek more information …
… compared with:
0800Z AUTO 29008KT 9999 OVC011 21/19 Q1012 RMK RF00.0/000.0
0902Z AUTO 20007KT 7000 SCT005 BKN011 OVC015 20/19 Q1013 RMK RF00.0/000.0
… with about 10 minutes to think about it and seek more information.
In the very inexperienced circles in which I move, “BKN003 OVC009” would cause considerable consternation in any event. “SCT005 BKN011 OVC015” – not so much, in the context of the 0800 SPECI.
But Kharon makes an important point about the converging temps/dew points and easing winds.
CASA says the decision should have been to divert, either way.
(And all this depends on assumptions about what was actually received and understood in the cockpit.)