Malaysian Airlines MH370 contact lost

[Ian W]

Originally Posted by cribbagepeg

Would a satcom person please step in? The raw bandwidth of a sat link is misleading. Individual A/C must either be polled (asked to transmit) or must speak up in the hope that data can be communicated. Simultaneous asychronous speakups - "collisions" - jam things up and the various originators must be separated in time, so they all get their data packets through. Because of transit time to/from the satellite(s), there is considerable latency involved, and at peak traffic times, actual throughput can be reduced to a fraction of the raw capacity of the sat channel. A small fraction.

This was covered extensively in the AF447 saga, and should be summarized here and "stickified" to reduce misconceptions. At least for the few that will read it before posing novice questions or "solutions".

Since the AF447 incident SATCOM capabilities have hugely improved. INMARSAT is providing far higher bandwidths from its new geostationary satellites as they have different antennas with smaller footprints within the overall geostationary footprint some of then steerable. INMARSAT is now offering 'mobile ISDN' at speeds from 64 to 128Kbit

Iridium is launching a new series of low earth orbit satellites (Iridium Next). Iridium satellites are rather like orbiting cell phone base stations and users have a 'connection oriented' datalink to the satellites. Again the data rates have been increased by orders of magnitude. Iridium already sells a system called SkyTrac that does much of the flight following task being discussed here.

With communications things are changing extremely fast.

[syseng68k]

thommo101, #9906:

There various schemes that could be used to mitigate that. For example, the beacon receiver could be switched on for just a short period, much as the transmitter is, to minimise the duty cycle. If the surface ship sends continuous pings at a sufficiently high rate, the receiver only has to catch one of those during it’s short on period. That then wakes up a microprocessor, enabling power to the transmitter, which starts sending back replies.

Also, 77mW sounds a bit high to me. A simple listening receiver should be doable for much less than that if low power operation is a design requirement…

[BillS]

We are still being subjected to posts about cell phones from MH370
The mods have done a great job removing most but there are still over 180 posts remaining on this thread.

Please, is it too much to ask that you read them - and also the many replies to them - before posting more?

[JohnH23]

ULB Power

The ping is 10ms long, thus the ENERGY per ping is 0.75*0.01 = 0.0075joules or 7.5mJ. ... At a rate of 1 per second, gives an effective average power requirement (ignoring circuitry – which should be pretty simple for a dumb pinger) of 7.5mW.

So, why not maybe change the ULB specs to slow the pinging down after the first week by halving the rate for each succeeding week.

[Wader2]

Originally Posted by JohnH23

So, why not maybe change the ULB specs to slow the pinging down after the first week by halving the rate for each succeeding week.

Or conversely have the longer silent for at least 48hrs, maybe even a week or more.

In the first 48 hours we have the ELB, then there is the inevitable transit time for suitably equipped surface vessels to arrive on the scene. Had it been the South China Sea 48 hours would have been fine.

[skadi]

I dont think that just position reports via satellite should be a problem. For example, in Germany all EMS-helicopters are fitted with a sat-datalink via Iridium and position/status reports ( incl. speed, course and height ) are transmitted every 2 minutes. And you dont need big antennas too, they are as small as GPS antennas. AFAIK Iridium covers almost the whole earth?

[Alloyboobtube]

There is no added safety with new recorders or continuous transmission , the only difference being that it may be found by now and a story about what happened, although nice to know still resulted in the deaths of 239 people.
If you picked up a live hijacking and shot down the aircraft then the result is the same as the ocean crash.
All aircraft boxes need CIrcuit breakers to protect wiring and prevent fires , they can all be turned off and that cannot change.

[snowfalcon2]

Alloyboobtube

There is no added safety with new recorders or continuous transmission , the only difference being that it may be found by now and a story about what happened, although nice to know still resulted in the deaths of 239 people.

Disagree. With new tech we can help prevent the next airplane go missing and save its occupants. If we just shrug, we'll eventually get more of the same type of accident as this.

All aircraft boxes need CIrcuit breakers to protect wiring and prevent fires , they can all be turned off and that cannot change.

However, by making a circuit breaker smart it can report if it was manually tripped ( = tampered with, unless there was a good reason) or by overcurrent.

[Blake777]

As a matter of interest, Hishamuddin has tonight denied the FO phone call story.

MH370 Tragedy: Hishammuddin refutes newspaper report co-pilot made phone call - Latest - New Straits Times

[Ian W]

Originally Posted by skadi

I dont think that just position reports via satellite should be a problem. For example, in Germany all EMS-helicopters are fitted with a sat-datalink via Iridium and position/status reports ( incl. speed, course and height ) are transmitted every 2 minutes. And you dont need big antennas too, they are as small as GPS antennas. AFAIK Iridium covers almost the whole earth?

skadi

Yes, Iridium low earth orbit satellites have global coverage including the poles.


Helicopters in the Gulf of Mexico have been using a similar SATCOM service from Outerlink ( www.outerlink.com ) for flight following for some years.

[susier]

Ocean floor likely conditions

'Zenith Plateau as the final resting place for MH370 Wednesday, 09 April 2014 22:14


The underwater search for the missing Malaysia Airlines MH370 has become focused on the Zenith Plateau in the eastern Indian Ocean, lying about 1000 km to its nearest point on the Western Australia coast, or 1680 km north-west of Perth. The plateau is surrounded by the extensive Wharton Basin to the west and north, joins to the Quokka Rise and Wallaby (or Cuvier) Plateau in the east, and to the south by the Perth Abyssal Plain. The origin of this plateau is proposed to be a fragment of continental crust that started rifting from the north-west Australian margin during the break-up of Gondwana in the Late Jurassic. The continued north-westerly migration of the India plate away from Australia resulted in extinct spreading ridges and volcanoes that blanketed the region in basaltic rocks during the Cretaceous. Subsequent drowning of the plateau in the Eocene has resulted in a thick build-up of calcareous ooze that now forms the present day seafloor.

The Zenith Plateau has a dimension of about 300 km wide in the east-west direction and about 220 km in the north-south direction. The plateau is relatively deep with its shallowest point at 1671 m and gently deepening towards the Wharton Basin in north at around 5000 m. The Wallaby-Zenith Fracture Zone forms an escarpment along the southern margin with a steep drop of between 2000 to 3000 m into a narrow trough with depths close to 6000 m. This narrow trough separates the Zenith Plateau from the adjacent Perth Abyssal Plain to the south.

The plateau is very poorly mapped with no modern multibeam surveys anywhere over this feature. Our current understanding of the bathymetry (depth) of the plateau are therefore based on older singlebeam echosounder data and coarse satellite gravity data. Within the present MH370 search zone on the northern flank of the plateau, seafloor depths range from about 3500 to 4500 m. The finer-scale seafloor topography in the search zone appears to vary by up to 300 m in height over distances of approximately15 km, but cannot be confirmed with the coarse data available.

Despite the deep depths on the plateau, the gentle sloping seafloor, (apparently) limited finer-scale topographic relief and the soft sediment nature of the seafloor, could provide a helpful background environment during the seabed search for the MH370 using the Bluefin-21 AUV's sidescan sonar and optical imagery.'


From Deepreef Explorer - Zenith Plateau as the final resting place for MH370

[Passenger 389]

ULB Duration

On 5th Apr 2014, 14:49, Green-Dot posted:

Just on CNN:

The MAS CEO declared during a press conference that the FDR / CVR - ULB maintenance records indicate that the ULB battery due date is June 2014.

At what intervals are the batteries usually changed? In general, how substantial (or how minimal) is the likely dropoff between the projected pinging duration (beyond 30 days) of a newly installed battery versus one due to be replaced soon? (I realize 30 days is the minimum requirement and that individual batteries may differ).

[robdean]

The case for acoustic transponders vs. current pingers

Deep-water Black Box Retrieval - November 2009, Volume 13, Number 09 - Archive - Hydro International

[lomapaseo]

Might as well prepare yourselves for the next 10,000 posts on this subject.

If they don't find any part of the airplane how many reasonable theories will be left ?

If they find only surface debris how many reasonable theories will be left?

If they do-not or can-not recover the black boxes but do find the aircraft on the bottom, how many reasonable theories will be left?

When considering what is a theory also give a thought to a possible viable corrective action, else the theory is worthless to even set forth inside our aviation community.

[p.j.m]

Originally Posted by GobonaStick

It might be possible, but I'd be surprised if anything was there - I've seen shipping lane data which shows that this part of the ocean stands out as being like the back of beyond when it comes to regular vessel traffic.

I'd be interested to know where the current AIS information is coming from. Prior to the SAR operation, there was never any details of shipping in that region, the best range you got was a few kilometres off the WA coastline.

[Two to Tango]

Interim report

Is a 30-day interim report expected from Malaysian air safety authorities?

[paulmoscow]

In general, how substantial (or how minimal) is the likely dropoff between the projected pinging duration (beyond 30 days) of a newly installed battery versus one due to be replaced soon?

ULB batteries are lithium (don't confuse them with rechargeable Li-ions.) They have a shelf life measured in years with very low self-discharge.

[glenbrook]

Originally Posted by broadreach

I expect that, for aviation related transmission, despite all the arguments about satellite bandwidth and the cost of transmitting continuous data from hundreds of thousands of flights every day, we will see affordable cost levels very soon.

Yes, there is a general trend towards continual data monitoring. We are increasingly being monitored everywhere now and there is no reason to suppose aviation to be any different. This is not driven for safety reasons but for cost and maintenance and revenue from data mining. General Electric, for instance is exploring a new revenue model for its engines. The falling cost of sensors, storage and bandwidth will allow them to charge airlines for thrust instead of selling engines. To do this will require precise and continuous monitoring of the engines with much greater detail than is currently done. In this case it does not have to be entirely real-time, of course, but there are other examples. The data from flights is rising quickly with the demand for on board wifi etc.

People will of course be demanding extra checks after the dust has settled on this tragedy, but that's because they forget just how strange this incident is. Aircraft failures in cruise are so rare that they hardly warrant a particular (probably expensive) fix, just because of a bizarre incident, which may be unique in the history of aviation.

The only thing I would like to see is some alarm to go off when a transponder is switched off. This should not be possible without alerting ATC or satellite message. I am very surprised something was not done about this after 9/11/01.

[deptrai]

edit: aireps you beat me there, re satellite ads-b ( like http://www.aireon.com/Home )

the main driver probably isn't safety (rather reduced separation minima, fuel savings, and eg weather avoidance on North Atlantic tracks), but it can help improve safety as well.

[VinRouge]

In the highly unlikely event of of this ever happening again what's to stop someone simply powering down the satcom unit?

I suggest regulatory work will be focused on the root cause rather than the disease... no point knowing that a crew member has gone UDI after the event. Regulatory barriers need to be placed pre-event, not after the fact.

Does the civilian world utilize a pre brief risk matrix including health and personal stress factors? I know it sounds silly, but the guys we have picked up at work (Mil) with ilness type issues only emerged when prompted at the risk matrix assessment stage done during crew in. They wouldn't have raised the issue unless prompted.

I have seen risk matricies for things like CFIT Risk for Ops assessment
here

but am not aware if the civilian world has equivalents for fatigue and mental/physical health factors.