Porker1 said
Am somewhat bemused by the JACC statement that the revised underwater search zone could be up to 700km (378NM) long. How can this tally with the CVR/FDR transponder pings picked up by the towed array and their reportedly short range? It either puts the provenance of these detections in doubt or implies they are being advised by experts that these high frequency acoustic signals can be channeled over greater distances.
and
Heathrow Flyer (quoting an independent Raytheon assessment of Inmarsat data) said:
The displayed initial estimated point seems somewhat inaccurate, as it implies that the aircraft performed a turn to the NW immediately after leaving radar coverage. On the basis of the presented information, it seems much more likely that the aircraft would have continued on its heading and that the initial satellite point should be located further south.
This would potentially have the effect of skewing the entire estimate satellite trajectory (and thus any impact point) by a number of miles.
This would tend to agree with the hypothesis that Ocean Shield's limited and non-continuous pinger detections were genuine (but distant) second or even third "convergence zone" in origin. Sound propagation in deep water tends to be distorted by thermoclines in the depths (abrupt changes of temperature at different levels in deep water (aka layering)). It tends to cause large amplitude focussed ripples in detected acoustics (i.e. an erratically moving incomplete annulus every 30 to 50 miles or so - at or near the surface). Accomplished and experienced sonar operators can tell the difference between first, second and third convergence zones. This effect for a sea-bottomed "pinger" might also be focussed in a particular direction by the ocean bottom's topography (think of MH370's pinger being inside a deep valley with its pinger's acoustics being channelled in the direction of the valley or canyon's mouth). Ocean hydrographers cannot predict or allow for these geomorphic effects and time-warps in detected ensonification. It's at the same time both diffraction and refraction via its water-routing - and for a bottomed object, reflection. The phenomenon is a great friend of submariners as it can cloak their actual position even when making noisy high-speed progress. All they need do is "hide" beneath a layer and noisily propagate in all directions. After swamping all listening sonobuoys and fixed arrays with their high-speed sound signature, they then slow and go to a silent undetectable loiter mode. Concentrating an MH370 sonics search within the immediate area of a few pinger detections was overly optimistic and seems to have disregarded the characteristics of sound in deep water.
Add in the Raytheon claimed discrepancy and it's still a much larger and indefinite search area than those you see on the AMSA/JACC charts. I guess we will see whether this will be reflected in the next phase search zone prognostications.
It's worth noting as far as range of detection goes, that a blackbox pinger's job is to be heard, whilst a submariner's intention is never to be heard - yet, in my experience, long distant detections during aerial ASW sonics search was the norm for conventional snorting and/or nuclear boats (particularly the Soviet Echo II boats and later).
Desert 185 said:
Unctuous:
Ref O2 fire...If you think this is a possibility, nowhere in the checklist does it say turn off the transponder and/or the ACARS, and do not talk to ATC, to include not declaring a emergency.
Fair comment for a mere nasty brown smell, but does not reflect what an injured crew might do after/during a sudden oxygen flare. There's no oxy on/off valve on the flight-deck and someone blinded by flame might just think that instantly killing the electrics might bring relief - from what is essentially a brief explosion and subsequent fireball. You only have to look at the cockpit photo of the MS 777 "Nefertiti" scorching to grasp that. I'd be surprised if they (or any surviving "he") didn't bale to the cabin immediately. But I'd also not be surprised if they were cooked where they sat.