coagie, the nice thing about the deep ocean, well over a thousand fathoms, (my best guess at how deep this beacon would be based on the area being searched) is that much of the surface noise would be attenuated (bends back up toward the surface) and thus raises the potential Figure of Merit for passive detection. That said, getting the sensor deep enough to have a chance at picking up a comparitively high frequency beacon poses some problems.
mm43 has covered the rest.

The USN has Towed Pinger Locater equipment containerized and ready to be flown to wherever required. Locating and chartering a suitable vessel to deploy the gear from will be the inital task.

@Hunter58


Both. All he seemed comfortable with was the initial return direction. Once he was pressed on any subsequent turns, he wasn't at all happy to be drawn. I'm sorry, I forget the exact words.


But I was left with the very firm impression that there wasn't solid supporting evidence for later changes of direction, but that he didn't want to admit that outright.

threl said,

Could be any number of "secrete" cites run by who knows who

...could also just be Indonesia or Singapore not wanting to publicly tell everyone how far off their coast they can pick stuff up

It's possible, that whoever is saying that they are using Inmarsat to narrow down the search area, is just using the feasibility of doing so, to cover for the real way they narrowed it down with whatever secret tracking method or equipment, but, it's only a possibility. I'd think that if such devices or methods were available to use in this case and worthy of secrecy, they'd have pinpointed the aircraft with them, but who knows?

The 'maximum detection range is 2 - 3km' which is fairly useless. As became clear in the Air France search what's required is a massive pulse to give a sensible range, delivered at far longer intervals to allow battery life to be extended.

One huge 'ping' every hour, for example, would have had this plane located by now, assuming it's under water.

Fast pulses, in an environment where everything moves slowly, are a waste.

cabin environment
 

From a former flight service manager / aviation human factors student and enthusiast:
(operated B733, 734, 738, 762, 763, 743, 744; A320, 332, 333 over the years)

I have been following this thread since inception. Very enlightening - thank you for all your insight, theories and discussion. :ok:

Lots of current talk about CVR duration - if some of the speculated theories are correct (decompression / hijack / smoke event et al.) I presume that in this technological age there will be recordings of this on camera-phones (and potentially even "water resistant" cameras) from within the cabin during any period of passenger consciousness.

In my many years of flying it has become apparent that there has been a recent surge of "pocket paparazzi" - everyone is eager to record any unusual events on mobile devices. Recent recordings / photos include evacuations (LOT, US Airways) and even relatively minor turbulence events etc.

In high-impact accidents it is still possible to find casualties intact - possibly with phones in pockets - I am intrigued to see if any media devices are recovered. Collaboratively with FDR / CVR information this may paint a very interesting (or horrifying) picture of the cabin environment prior to impact. Perhaps stored data may yield clues in this eventual investigation, regardless of FDR / CVR recovery or analysis.

I am unsure of current protocols about eventual release of this potential media device information - does it "belong" to the estate of the deceased or can it be released for "public consumption" via official channels? Does anyone have any insight?

CVR
 

Agree that two hours of recording sounds ridiculous nowadays. But with a good software you can unerase or undelete what has been rewritten on a disk. Let's hope that, at least, the recorders are found.

Thai have seen the MAS370 on their radar and didn't care because not their competence area. Vietnamese have seen the aircraft turning back, warned the Malaysian that said thank you because they are well educated. Indonesian have seen nothing or may be have seen something, but it would be a defence top secret because they are not supposed to. Singapore is mute. Malaysian discover that the MAS370 fled across their territory some days after, making some nice turns while Malaysian Air Farce was sleeping. What else?

@DespairingTraveller

Maybe said official also remembers the Masaysian Air Force going quiet on the subject althoigh they had briefed the public about exatly said track. So in order not to get whacked by the PM he backtracked as much as possible.

I believe the Air Force was right in the first place as even their back pedaling was nicely put refering to an earlier press conference.

If you have a big sound receiver you can hear things that are a long way down.

There were rumors that the French submarine Emeraude that went looking for AF447 couldn't really exploit its listening equipment to the full because while it was large, it didn't have much sensitivity at such high frequencies.

Do the Australian navy have ships with suitable big sonar to hand? They seem to Leeuwin-class survey vessel - Wikipedia, the free encyclopedia but on the wrong side of the country. Looks like there should be room for some extra stuff onboard if the US has a special 40+ KHz sensitive device.

Not quite. One first has to get within a reasonable range of the source, and they have not yet found the debris they think is from the plane, nor yet had a shot at working from that location (presuming they find it) back along the best calculated wind/surface current movement track to a reasonable first search datum. Once that's sorted, then a sensor can be lowered into the ocean to try and hear the ping.

Let's not put the cart before the horse. :8

Underwater Locator Beacon Search
 

The AF447 report lists the effective range of the ULBs on the two recorders as 2 to 3 km. That's slant range, so if the water is deep, the hydrophones need to be lowered substantially, and of course good bathymetry (i.e., and underwater terrain map) helps a lot.

Main page for AF447 data:

FLIGHT AF 447

Sea Search Operations (31 MB):

http://www.bea.aero/fr/enquetes/vol....11.2012.en.pdf

"Both of the flight recorders of the aeroplane were equipped with a ULB designed to locate it when immersed. The duration of ULB transmission is at least thirty days from immersion(10). . . . As a rule, acoustic searches should always be preferred during the transmission time of the beacons. They are more effective than searches using sonar, magnetometers or video cameras.

The maximum range(11) of these beacons is of the order of 2,000 to 3,000 m. However, in the search area the average depth was 3,000 m. It was therefore necessary to bring the hydrophones(12) closer to the source of transmission, by towing specialized equipment nearer to the seabed.

(10)The regulatory minimum is 30 days, but the ULB manufacturer stated that the transmission duration was in reality of the order of forty days. This figure is determined by the capacity of the internal battery.
(11)It may be necessary to take into account the propagation of acoustic waves in a liquid medium, which depends on numerous interconnected parameters, such as the salinity and temperature of the water. When an acoustic wave is propagated in the sea, it is subject to refractions, which generate multiple trajectories. It can also happen that the acoustic waves are deflected in such a way that there is an area of shadow that is never reached by these waves.
(12)Undersea microphone. "

"The TPL20 and TPL40 systems are deep-towed devices belonging to the family of the “Towed Pinger Locators” manufactured by Phoenix International for the US Navy. The United States government made both the equipment and the associated operators freely available to the French government (17 people distributed on the two ships). In June 2009 the TPLs were the only systems capable of carrying out passive acoustic searches over large areas at significant depths.

The two TPLs are towed devices each equipped with an omni-directional hydrophone which can operate down to depths of six thousand metres with towing speeds ranging from 1.5 to 5 knots. They can be installed on all types of appropriate vessels capable of carrying a load weighing around 25 tonnes. A mapping software application uses GPS positioning information to follow the ship’s movements and the position of the towed device. The latter is equipped with a pressure sensor that permanently transmits the immersed device’s approximate depth of submersion. Management of the deployed cable length and ship towing speed is used to place the acoustic sensor at the required average submersion depth For example, an average submersion depth of 2,300 m for the TPL is achieved by deploying approximately 6,000 m of cable at a towing speed of 3 knots."

Much more interesting information in the report, such as description of an acoustic repeater that downconverts the 37.5 kHz signal to 12 kHz to be compatible with other sensors onboard a ship.

On using the French nuclear-powered submarine Emeraude:

"The Emeraude is equipped with numerous acoustic sensors including a sonar interceptor which was used during the search operations. This equipment was not originally designed to detect and localise ULB type acoustic beacons, but thanks to the optimisation of its settings and the use of additional computer software from 30 June 2009, its signal detection capabilities were enhanced."

"Deployment of the nuclear-powered submarine improved the search system and provided an interesting mobile device in terms of the surface areas covered (its average speed in the zone , between 6 and 10 kt, was higher than that of the other resources deployed). However its use proved difficult, given the safety constraints resulting from its integration in the search operations.
The presence of the nuclear-powered submarine meant that a vast safety zone had to be put in place around its patrol area in order to avoid any collision between the various pieces of towed equipment and the submarine. This permanent preoccupation with safety required delicate management of the undersea zones."

Interim report on search for ULBs:

Final report

"The first search phase aimed at detecting and locating the acoustic signals transmitted by the Underwater Locator Beacon (ULB) fitted on each flight recorder(8). As a priority, the aeroplane’s planned flight path as well as the greatest possible area inside the 40 NM circle was swept by two Towed Pinger Locators (TPL)(9).
No signal from either of the beacons was detected by the sensors deployed in the area despite TPL passing by, on two occasions, not far from the debris field, on 22 and 23 June 2009.

(8)There were two beacons on the A-330, one attached to the cockpit voice recorder (CVR) and the other to the flight data recorder (FDR).

(9)The two US Navy TPL’s are the only two towed hydrophones in the world able to operate to a depth of up to 6,000 metres."

Report on tests of similar ULBs:

http://www.bea.aero/fr/enquetes/vol....nt.09.2011.pdf

"Masked areas are present on the beacon’s vertical axis as well as the horizontal axis, leaving the possibility of significant of "shadow" zones. . . .
- It should be remembered that each time the level falls 6 dB(micro)Pa, the signal’s theoretical range falls by half. For beacons attached in this way on a flight recorder this can be very noticeably reduced, depending on orientation, in relation to the theoretical range of a single beacon."

The CVR can't be "undeleted" or recovered because the data overwrites the previous in a circular buffer sort of arrangement. You can only recover data from a hard drive if it hasn't been written over with a new file.
:8

Primary Radar -- Was Anybody Minding the Store?
 

We see a whole bunch of delay in hearing from the various militaries.

It sure looks to me that any primary echo data shared with the SAR effort has come from examining recordings.

The inference is that MH370 echoes did not get attention from anybody on a scope/display in Malaysia, Thailand, India, or Indonesia.

Were the folks watching scopes in Burma, China, Pakistan, Kazakhstan more on the ball?

Fuel load
 

@Alchad

Earlier Bloomberg article quote:

"The Boeing 777 was carrying 49.1 metric tons (54.1 tons) of fuel when it departed Kuala Lumpur, for a total takeoff weight of 223.5 tons, according to Subang Jaya-based Malaysian Air."

Whether that is "normal" for the planned flight path I leave to the pilots who know these machines.....

Weather will improve over the weekend in the search area which is good.
Currently low cloud and rain.

This is a video from the RAAF Orion that shows a bit of footage
of the sea.

Missing plane: on board the search flight

DOES ANYONE KNOW if malyasian air has a pilot's union? IFALP?

wondering why we haven't heard from them if they have one?

glendalegoon
I THINK I heard the minister in a Malaysian press conference say that all the cabin crew were in a union, but not the pilots. Only just audible, and a rapidly swallowed aside.

Incidentally, I wish they had a radio mike to pass to questioners, or the chair would précis questions to the microphone. So annoying, and gives such a bad impression, to hear, again and again, the answer but not the question.

Most likely this data was shared by India. They dont want to reveal capabilities of their Andaman radar. If you notice India was quick to suspend the search in Bay of Bengal on 15th March, once they reviewed their radar tapes. Inside info from Indian Naval command is that India provided significant amount of radar data to Malaysia on 15th or 16th March. The other country could be Australia.

These countries do want to be anonymous due to several known reasons.