slats11:
As Victor noted in a pvt email, there are three possible explanations for the fact that MH370 has not been found so far. I agree.
1. After the FMT, the plane descended to a much lower altitude and corresponding lower speed and crossed the 7th arc much further north
2. The math and assumptions were correct but the plane was missed during a sonar scan pass.
3. The math and assumptions were correct until 00:19 but the plane glided away from the 7th arc and out of the search zone.
In light of what we are learning about the underwater terrain, and the probability of missing the plane due to that difficult terrain, #2 is the most likely explanation. Below follows a report from a friend who attended Kim Picard's presentation in Canberra 2 days ago.
My report from the meeting.
• Kim P did use a taxonomy for types of seafloor topography, not recorded (no pen dammit). However, it doesn’t make much difference because all of the seafloor of interest south of Broken Ridge (ie all of the recent “Bayesian contours” area) is classified as “spreading ridge”, the basic characteristic of which is “rugged”.
• There are “about 220” volcanoes in the examined spreading ridge seafloor south of Broken Ridge, all deemed to be associated with the spreading ridge when active in the area. Given the limited width of the search area there must be many more in the surrounding areas. Interestingly there were two small relatively recent volcano structures on the north (continental) side of Broken Ridge, for which no explanation exists, and one newer volcano closer to the spreading centre (south) which has a quite different smoother profile than the other volcanos.
• Seismic activity was not mentioned, but of course the spreading ridge is still active and so earthquakes will arise from the transform fault at the southern end of the Geelvinck Fracture Zone.
• Re “will parts sink into the mud”, basically, NO. The sea floor is covered in ooze, between 100 and 300 metres thick. The deeper parts of the abyssal plain (>4500 metres) are below the “carbon compensation depth”, the effect of which is to redissolve any carbonate that makes it to that depth, leaving oozes below that depth to be reduced to just the siliceous component (diatoms and radiolarians in particular, plus dust). Either way, only the top 20cm is “soft”, with anything below that dewatered and relatively hard. Hence, anything that drifts down and is larger than 20cm will definitely reside on the surface. The French jet that crashed into the Atlantic out of Brazil was found in pieces resting on top of a mud pool at depth.
• The search proceeds in phases – the first phase is the mapping of the sea floor (done I think) and the second phase is the search for the plane. The first phase was with low resolution shipborne sonar; but only relatively low – its 300m resolution is much higher than the existing satellite scan still applying to the surrounding areas as the images on the GA site attest. The second phase (currently under way I understand) uses a towed high resolution sidescan sonar device. The sonar device is towed 10km behind the ship with it being about 100 metres above the seabed, the scan goes out sideways to 900m making a very shallow illumination at the side of the scan, allowing for large shadows in high relief (as above, the predominant topography). The beam width shown on one chart was 1deg vertical by 1deg horizontal, for a net resolution of about 10cm. The “find plane” requirements were crafted to find something the size of an aircraft engine, and to characterise it unmistakeably as such. One sonar device was lost recently when it was dragged into a mount (not a “mud volcano” as reported) but has since been found. If they can find something the size of a landing gear strut …
• The topography and time taken for high res scans means that there are currently many areas which are in shadow from the high res scan. However, KP was quite clear that the ATSB would be sending a UUV back to explore all shadowed areas such that “no stone was unturned”.
• Kim is happy to engage in more discussion with Mike about the geology and topography of the area if he’d like.
Re the BIG QUESTION: what is the possibility that the aircraft has been missed in areas already searched?
• The search is not complete so, yes, the plane remains may be in a deep/steep area, already identified in the ship sonar and shadowed in the sidescan sonar, which is yet to be visited by the UUV. Probability? Small but not trivial, reducing as the sidescan and UUV program proceeds.
• The resolution of the existing high res scanned areas, and the extensive/multi pass review of that data (that happens as it comes in, there isn’t a backlog of unseen data) means that there is VERY LITTLE chance that a field of aircraft fragments would not be spotted if they were out in the open. Check out the images of the shipwrecks that have already been found in that area – one of which is itself fragmented.
• KP was clear that the search information will be made available when the ATSB completes the search.
As Victor noted in a pvt email, there are three possible explanations for the fact that MH370 has not been found so far. I agree.
1. After the FMT, the plane descended to a much lower altitude and corresponding lower speed and crossed the 7th arc much further north
2. The math and assumptions were correct but the plane was missed during a sonar scan pass.
3. The math and assumptions were correct until 00:19 but the plane glided away from the 7th arc and out of the search zone.
In light of what we are learning about the underwater terrain, and the probability of missing the plane due to that difficult terrain, #2 is the most likely explanation. Below follows a report from a friend who attended Kim Picard's presentation in Canberra 2 days ago.
My report from the meeting.
• Kim P did use a taxonomy for types of seafloor topography, not recorded (no pen dammit). However, it doesn’t make much difference because all of the seafloor of interest south of Broken Ridge (ie all of the recent “Bayesian contours” area) is classified as “spreading ridge”, the basic characteristic of which is “rugged”.
• There are “about 220” volcanoes in the examined spreading ridge seafloor south of Broken Ridge, all deemed to be associated with the spreading ridge when active in the area. Given the limited width of the search area there must be many more in the surrounding areas. Interestingly there were two small relatively recent volcano structures on the north (continental) side of Broken Ridge, for which no explanation exists, and one newer volcano closer to the spreading centre (south) which has a quite different smoother profile than the other volcanos.
• Seismic activity was not mentioned, but of course the spreading ridge is still active and so earthquakes will arise from the transform fault at the southern end of the Geelvinck Fracture Zone.
• Re “will parts sink into the mud”, basically, NO. The sea floor is covered in ooze, between 100 and 300 metres thick. The deeper parts of the abyssal plain (>4500 metres) are below the “carbon compensation depth”, the effect of which is to redissolve any carbonate that makes it to that depth, leaving oozes below that depth to be reduced to just the siliceous component (diatoms and radiolarians in particular, plus dust). Either way, only the top 20cm is “soft”, with anything below that dewatered and relatively hard. Hence, anything that drifts down and is larger than 20cm will definitely reside on the surface. The French jet that crashed into the Atlantic out of Brazil was found in pieces resting on top of a mud pool at depth.
• The search proceeds in phases – the first phase is the mapping of the sea floor (done I think) and the second phase is the search for the plane. The first phase was with low resolution shipborne sonar; but only relatively low – its 300m resolution is much higher than the existing satellite scan still applying to the surrounding areas as the images on the GA site attest. The second phase (currently under way I understand) uses a towed high resolution sidescan sonar device. The sonar device is towed 10km behind the ship with it being about 100 metres above the seabed, the scan goes out sideways to 900m making a very shallow illumination at the side of the scan, allowing for large shadows in high relief (as above, the predominant topography). The beam width shown on one chart was 1deg vertical by 1deg horizontal, for a net resolution of about 10cm. The “find plane” requirements were crafted to find something the size of an aircraft engine, and to characterise it unmistakeably as such. One sonar device was lost recently when it was dragged into a mount (not a “mud volcano” as reported) but has since been found. If they can find something the size of a landing gear strut …
• The topography and time taken for high res scans means that there are currently many areas which are in shadow from the high res scan. However, KP was quite clear that the ATSB would be sending a UUV back to explore all shadowed areas such that “no stone was unturned”.
• Kim is happy to engage in more discussion with Mike about the geology and topography of the area if he’d like.
Re the BIG QUESTION: what is the possibility that the aircraft has been missed in areas already searched?
• The search is not complete so, yes, the plane remains may be in a deep/steep area, already identified in the ship sonar and shadowed in the sidescan sonar, which is yet to be visited by the UUV. Probability? Small but not trivial, reducing as the sidescan and UUV program proceeds.
• The resolution of the existing high res scanned areas, and the extensive/multi pass review of that data (that happens as it comes in, there isn’t a backlog of unseen data) means that there is VERY LITTLE chance that a field of aircraft fragments would not be spotted if they were out in the open. Check out the images of the shipwrecks that have already been found in that area – one of which is itself fragmented.
• KP was clear that the search information will be made available when the ATSB completes the search.