I plotted a hypothetical path from VAMPI to Ocean Shield's location (20.8S 104.1E) under the assumption that the plane was flown about 200 mi north of Banda Aceh in order to avoid Indonesian radar. At this segment of the hypothetical flight the plane might also have been at a somewhat lower altitude in order to stay below the Indonesian radar horizon.

I come up with almost 2300 NM for that flight path (I don't know where you placed last radar contact with Malaysian radar); how does this fit in with your estimate?

I was looking at the map of the undersea search area posted by Shadoko and then looked up the AIS information for the current position of Ocean Shield, which is approximately 21 S, 104 E. That longitude looked very familiar.

If you go north along the meridian to about 7 N, you end up within 25 nm of the IGARI waypoint (6.9367 N, 103.5850 E)

Just coincidence? If they do recover the FDR, the actual track is going to be very interesting.

Nowhere near 200 miles north of Aceh. It was tracked out to about 10 NM beyond MEKAR on a bearing of about 285T from Butterworth AFB. MEKAR is 87 NM line of sight from Banda Aceh ARP. By NILAM it's 81.1 NM LOS. Intersection VAMPI is about 65 NM to Lhokseumawe. ICAO's FASID CNS/4A states both Banda Aceh and Lhokseumawe/Malikussaleh's PSR ranges are 90 NM. Apparently 60 NM might be closer to the truth.

MH370 was below Butterworth's RADAR horizon for a significant period enroute VAMPI. You can see that here:

http://www.aqqa.org/MH370/img/ButterworthPSRb_sml.jpg

From photo.china.com.cn

As commented above, if last known radar contact is near NILAM and MH370 wasn't visible to Indonesian radars at that point, it's pretty straightforward to get from NILAM to 20.8S 104.1E in less than 2000 NM without getting any closer.

If radar slide is false though, MAPSO-IGREX-TOPIN-IKASA-Ocean Shield is 2213 NM (370 kts) while giving a wide berth to Indonesian airspace.

Incidentally, Ocean Shield spent the last day within 20 NM of a major waypoint corridor from India to west Australia. Interesting coincidence. Remember how roaring 40's were a big problem because no corridors went there? This area is not.

Ocean swells in the Indian ocean well off the WA coast are usually long period, tending towards 30 second peak-peak - perhaps 25 second typical.

They are usually generated by deep polar lows and have travelled thousands of kilometres from near Antarctica. Alternatively cyclones in the North-West can generate them.

Wave amplitude in deep water is not particularly large for this type of swell. Breaking waves would be extremely unusual.

A landing parallel to the swell is quite feasible and there will be little or no effect from the swell during the expected very short landing period. This applies to the original search area SW of Perth and now to the search area NW of Perth.

The telegraph has some more information on what caused the last partial ping:

MH370 missing plane: 'black box pings' tracked to same point as final 'half-handshake' - Telegraph

If final ping represented fuel exhaustion in the cruise, we need to explain why the plane apparently ditched on the same arc as fuel exhaustion. This also requires plane to cover perhaps 120km in last 8 minutes of powered flight (= 900kmh or approx 480 knots). Even if plane was flying perpendicular to arcs, speed would still have been 380 knots (50NM in 8 minutes).

However if ditching would you really wait until fuel exhausted? Surely you would prefer to have a bit of control over the last few seconds of flight.

If had power at time of ditching and the final ping represented the ditching itself, what could account for final partial ping? Possibly loss of antenna. This scenario requires plane to cover same distance as above, as well as losing altitude and slowing down for ditching in 8 minutes.

On balance, this suggests ditched after fuel exhausted. So perhaps it flew along the arc when ditching. Or perhaps was already very low altitude in order to assess sea conditions when fuel exhausted, and ditching only a few km further on.

LCH77;
Please tell me this isn't true. The nightmare scenario of some misguided or malicious person dropping a pinger overboard in the search area doesn't bear thinking about.

Is there any actual evidence suggesting MH370 went North, West, and then South to avoid flying over Indonesia or is it based solely on the Indonesians saying they never picked the plane up on radar so it couldn't have flown over their airspace?

Absence of evidence is not evidence of absence.

Near as I can tell, the only actual radar evidence comes from the Malaysian military tracking the flight and showing that it made a westward turn near IGARI, headed back across Malaysia and into the Malacca Straight before disappearing again near Pulau Perak. Everything the media is reporting about the path it took after that is just speculation based on what other countries say they did NOT see that night.

anyone have a link to the cnn video.

this video show the rib

http://edition.cnn.com/2014/04/08/wo...html?hpt=hp_c1

The whole thing is apparently irrational and an assumption of fuel exhaustion is just that, an assumption.

The same effect would be achieved by manoeuvring for ditching while still retaining power for ditching. That alone would account for not travelling as far south.

Professor Mishar Dohler* opined right at the outset that the final ping could have been as the aircraft sank.

*King's College London - Professor Mischa Dohler

With all that high-tech sonar equipment in the Southern Indian Ocean there must be a temptation to 'sound out' the capabilities of the 'opposition'.

There must be as much effort being put into not giving anything away as there is in finding the aircraft.

The conspiracy theories you lot come up with :rolleyes:

Yes, they might not use the latest and greatest but remember the two navies have worked together before with ship under way and other live fire exercises so it is not totally new to each other.

Doppler
 

For all the intelligent discourse earlier in this thread regarding Doppler effects of electromagnetic waves, the mention of Doppler with respect to sound waves is curiously missing even though the effect is far more pronounced. The odds of getting precisely a 37.5 kHz return in an extremely noisy ocean are pretty low, at any considerable distance from the source.

These underwater sounds that have been heard may be the haystack we are looking for, or they may not. The odds are not in our favor without some kind of verified physical debris in hand. We shouldn't get our hopes up until then.

Doppler
 

The effect is more pronounced with acoustics.

It will be useful if the the frequency is exact, it isn't. There will be a frequency difference when you travel towards or away.

The frequency of a soft ping will be difficult to detect accurately.

@iamhere 9586

What else is going to be transmitting on 37.5kHz in the Indian ocean ?
Lets try this again.
The media say the authorities say that they believe the signals are comming from a flight data recorder.
Only believe
What else is going to be transmitting on 37.5kHz in the Indian ocean ?

Suggest you listen to this . BBC Radio 4 - Broadcasting House, 06/04/2014 ..about 09:53 minutes in... which gives a pretty authoritative explanation as to WHY they are being cautious.

Very interesting thanks. But that seems to be in reference to the Chinese observations not the Ocean Shields. In fact they comment that had it been the Ocean Shield that would have been better. I assume that was before Ocean Shield made their observations.

I think a Trent engine windmilling will keep a genny on line, providing the TAS remains reasonably high, so the partial ping will not necessarily coincide with fuel exhaustion time.

Right, it wasn't exactly 37.5 kHz. It was 33.2kHz. They believe this is still indicative of the pingers, as the AF447 was transmitting at ~34kHz. But the cadence/interval of both pings (1Hz) did match, that's why they believe it is a legit detection.

re the Chinese RIB, I believe that was a handheld detector. (the kind the Chinese have is designed for shallow water/handheld use e.g. by a diver)

On the B777 does the RAT automatically deploy with a loss of both generators?