Malaysian Airlines MH370 contact lost
It doesn't invalidate the greater southern path, which put the possible crash site in a much broader area - about 1,200km long - than the region from which the suspected 'recorder pings' were coming.
The Bluefin searched 850 square km. That search took about a month (there were a few interruptions due to equipment problems, which will also occur in any subsequent search).
Assume the flight ended right on on the final arc, which we believe has a resolution of approx 10km "wide." That is 1200 x 10 = 12000 square km. Thats at least 12 months.
If we assume MH370 could have glided say 100km beyond the final arc, thats 120000 square km or perhaps 10 years.
Then you have to allow for increased technical and logistic difficulties as the search goes further south. The initial search was relatively close to Australia and in relatively calm waters. It will get far harder as you search further south.
Who is going to fund this?
Sure you can use multiple AUVs, but we are still looking at years.
I fear we are going to need another source of information to narrow the area down significantly.
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Nope, I only got the cut from MH Malaysia Airlines B772 Missing Enroute KUL-PEK Part 64 — Civil Aviation Forum | Airliners.net
Post 38 discusses the source.
Post 38 discusses the source.
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Since circumstances have changed I will repeat my suggestion that was previously "modded".
In my experience aircraft can only fly TO an FMC fix. Now, as a pilot in an aircraft west of Indonesia who wishes to fly the aircraft on an unlikely track for a long enough period of time to ensure it runs out of fuel what fix position would you enter into the FMC to meet these needs, a fix position that requires no great imagination. Obviously the geographic South Pole.
If anyone is taking bets I would locate the aircraft on a track from its last known position to the geographic South Pole and a distance along track to a little beyond the last Inmarsat ping.
In my experience aircraft can only fly TO an FMC fix. Now, as a pilot in an aircraft west of Indonesia who wishes to fly the aircraft on an unlikely track for a long enough period of time to ensure it runs out of fuel what fix position would you enter into the FMC to meet these needs, a fix position that requires no great imagination. Obviously the geographic South Pole.
If anyone is taking bets I would locate the aircraft on a track from its last known position to the geographic South Pole and a distance along track to a little beyond the last Inmarsat ping.
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If you read the JACC press release a few posts back, they appear to be planning to search up to 60,000 square kilometres, and expect it to take up to a year. If they start in the most probable areas, hopefully they won't have to search all 60,000 before they find it, but that would appear to cover an area tens of kilometres wide along the entire final arc.
In my experience aircraft can only fly TO an FMC fix. Now, as a pilot in an aircraft west of Indonesia who wishes to fly the aircraft on an unlikely track for a long enough period of time to ensure it runs out of fuel what fix position would you enter into the FMC to meet these needs, a fix position that requires no great imagination. Obviously the geographic South Pole.
Looks like a decent bet.
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Asking for clarification
From the JACC:
Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.
What it means?- that the Bluefin has only searched the areas within its operating limit?
or
- that all the area in the vicinity of pings was within its (upgraded) operating limit?
Sorry to ask something perhaps evident for all but not for me as a French speaking native
Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.
What it means?- that the Bluefin has only searched the areas within its operating limit?
or
- that all the area in the vicinity of pings was within its (upgraded) operating limit?
Sorry to ask something perhaps evident for all but not for me as a French speaking native
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In my experience aircraft can only fly TO an FMC fix
that requires no great imagination. Obviously the geographic South Pole.
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Blue-fin operations
Shadoko:What it means?- that the Bluefin has only searched the areas within its operating limit?
or
- that all the area in the vicinity of pings was within its (upgraded) operating limit?
or
- that all the area in the vicinity of pings was within its (upgraded) operating limit?
Consequently there maybe smaller areas that were not scanned, but bluefin-21 had done the majority of the area.
Recall that the AF scanning "missed" the major debris field, it was after WHOI (as a private contractor) was engaged that they located the field close to where it was expected almost a year earlier (and in an area that had been previously scanned)
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Asking for clarification
From the JACC:
Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.
From the JACC:
Yesterday afternoon, Bluefin-21 completed its last mission searching the remaining areas in the vicinity of the acoustic signals detected in early April by the Towed Pinger Locator deployed from ADV Ocean Shield, within its depth operating limits.
The Australian Transport Safety Bureau (ATSB) has advised that the search in the vicinity of the acoustic detections can now be considered complete and in its professional judgement, the area can now be discounted as the final resting place of MH370.
Well, that's how I understand it but could be corrected.
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porterhouse
Yes, heading select could be used but if you wanted to remove all human intervention from subsequent events you would use the FMC.
And something like 90S 90E has a certain attractive simplicity. The man we are working with has demonstrated that he was a planner and he was thinking ahead, he would not choose a random position.
Yes, heading select could be used but if you wanted to remove all human intervention from subsequent events you would use the FMC.
And something like 90S 90E has a certain attractive simplicity. The man we are working with has demonstrated that he was a planner and he was thinking ahead, he would not choose a random position.
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within its depth operating limits.
That is a ryder to the statement and to me causes confusion/doubt , why add it?
These pings, what were they? A fault in the ship or TPL electronics that caused a piece of circuitry (probably an amplifier) to go into oscillation not an unusual fault, BUT asking for it to be intermittent at a regular mark to space ratio of 1.1sec and 33.7kc , sorry I find that one difficult.
Be interesting to see where the next search starts, any bets on it being the failed bluefin search area.
That is a ryder to the statement and to me causes confusion/doubt , why add it?
These pings, what were they? A fault in the ship or TPL electronics that caused a piece of circuitry (probably an amplifier) to go into oscillation not an unusual fault, BUT asking for it to be intermittent at a regular mark to space ratio of 1.1sec and 33.7kc , sorry I find that one difficult.
Be interesting to see where the next search starts, any bets on it being the failed bluefin search area.
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Not a pinger
The 1.1 second pulse rate and the frequency sound about like a hydrographic sonar system I worked on designing back in the late sixties. At 4800 feet per second in water and a two way path that is appropriate for depths of 2500 feet. The pulse width we used was in the 5 to 25 millisecond range depending in part on the bottom material which has varying reflectance qualities at 33 KHz.
But that range limitation is only if you only have one pulse in the water at a time. For the higher range sonar chart recorders we could have 8 or 10 pulses in the water at a time. The chart and some memory let us focus on the bottom profile so the multiple return echos were easy enough to identify... if you did a few 1 pulse soundings to get the bottom range. Something like the old Omega nav system: you had to know where you were to get started.
Our sonar output used a very large transducer to help focus the signal. But not too narrow a beam because of survey vessel roll. With 500 to 2000 watts into a good transducer the range to a sensitive receiver would be very long. Certainly many miles. The signals heard may have been an echo off the bottom.
The reported frequency of the pings sounded much too low and that deviation from spec was apparently considered a possible consequence of low battery voltage. But maybe the frequency did not go down further. I would be very surprised that the resonator could go more than 2-3 KHz off the centre frequency due to dropping battery voltage.
I would hope someone obtained an identical pinger and measured the output frequency with decreasing battery voltage.
But that range limitation is only if you only have one pulse in the water at a time. For the higher range sonar chart recorders we could have 8 or 10 pulses in the water at a time. The chart and some memory let us focus on the bottom profile so the multiple return echos were easy enough to identify... if you did a few 1 pulse soundings to get the bottom range. Something like the old Omega nav system: you had to know where you were to get started.
Our sonar output used a very large transducer to help focus the signal. But not too narrow a beam because of survey vessel roll. With 500 to 2000 watts into a good transducer the range to a sensitive receiver would be very long. Certainly many miles. The signals heard may have been an echo off the bottom.
The reported frequency of the pings sounded much too low and that deviation from spec was apparently considered a possible consequence of low battery voltage. But maybe the frequency did not go down further. I would be very surprised that the resonator could go more than 2-3 KHz off the centre frequency due to dropping battery voltage.
I would hope someone obtained an identical pinger and measured the output frequency with decreasing battery voltage.
Last edited by ve7pnl; 29th May 2014 at 22:20. Reason: typo: pulse width, not rate
I would hope someone obtained an identical pinger and measured the output frequency with decreasing battery voltage.
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Originally Posted by gonebutnotforgotten
... if these pings came from the searching ship(s), why did they disappear, roughly at a time when the original locator batteries were expected to die?
#1 ping detection apparently occurred as the TPL was in the process of being lowered, I think around the 250 ~ 300m mark and while the vessel was moving slowly ~0.5 knots. The detection was lost after 2h 40m, and it is possible that if the source was on the Ocean Shield, that could be an explanation if the tow catenary had lengthened to beyond the detection range.
#2 ping detection was 7.16NM by 205°T from the initial #1 ping and about 5 hours later as the vessel was returning on a reciprocal track, but only for a short duration. The timer on the ship's bar door had started! Think of any other explanation?
#2 ping location was the center of the 10km radius on which the Bluefin-21 search grid was based. JACC's reference to the search being centered on the 2nd ping detection of 8 April was not correct.
Last edited by mm43; 30th May 2014 at 01:40. Reason: added dist & brg info
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On the floor?
#1 ping detection apparently occurred as the TPL was in the process of being lowered, I think around the 250 ~ 300m mark and while the vessel was moving slowly ~0.5 knots. The detection was lost after 2h 40m, and it is possible that if the source was on the Ocean Shield, that could be an explanation if the tow catenary had lengthened to beyond the detection range.
#2 ping detection was 7.16NM by 205°T from the initial #1 ping and about 5 hours later as the vessel was returning on a reciprocal track, but only for a short duration. The timer on the ship's bar door had started! Think of any other explanation?
I always thought the plane was floating at a great depth and drifting south at about 1 kt which accounted for the long first encounter.
Pings 3 and 4 killed that theory.
#2 ping detection was 7.16NM by 205°T from the initial #1 ping and about 5 hours later as the vessel was returning on a reciprocal track, but only for a short duration. The timer on the ship's bar door had started! Think of any other explanation?
I always thought the plane was floating at a great depth and drifting south at about 1 kt which accounted for the long first encounter.
Pings 3 and 4 killed that theory.
Given it took a month to search 850 km2 (possibly with some deep areas missed), the proposal to search 60,000 km2 suggests a different methodology. Perhaps using multiple more capable AUVs.
Anyway the dramatic increased size of the proposed area suggests we are really back to the Inmarsat arcs.
I guess a ditching is an advantage here. We will presumably be looking for a large relatively intact fuselage rather than a debris field.
Anyway the dramatic increased size of the proposed area suggests we are really back to the Inmarsat arcs.
I guess a ditching is an advantage here. We will presumably be looking for a large relatively intact fuselage rather than a debris field.
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Originally Posted by RayCee
I always thought the plane was floating at a great depth and drifting south
The aircraft will be on the bottom - wherever that may be.
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Yeah the 777 landed perfectly without any damage. Then no doors or evacuation was commenced. It then sank to the bottom perfectly intact and therefore no debris.
What utter nonsense!
What utter nonsense!