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Toys, I don't think that anyone here is saying that the satellite images were positively identified as being 777 debris, or indeed that they were conclusively debris at all. The images were of objects which merited further investigation. What we [i]are[/i] saying is that some bloke browsing on the internet could not realistically discredit the images, especially when other people, who are presumuably trained in the business of photographic interpretation, have already looked at them.
This thread is more interesting than the main media outlet coverage.
Probably because we have more people with scientific understanding on here than all the journos on all the media put together.
Regarding the debris, the chances are that the vast majority of sightings are going to be false leads. Hence those dismissing them based on just what they can see on the internet are going to be proved right. That is until some real debris turns up. It's all very self-fulfilling based on the odds involved.
Reading The Times at lunch, there was a news piece in there saying that some UK based firm of lawyers was "advising" the relatives that the most likely cause was an electrical fire or short causing the crew & passengers to become incapacitated, the aircraft continued flying as a ghost plane until it ran out of fuel and crashed.
They;'re saying this based on having worked on some other aviation cases and because if it's mechanical failure rather than deliberate crew sabotage, it allows them to sue Malaysian Airlines... So no motive there then... 😉
I'm only ribbing anyway, lets face it we don't have a clue, neither do they...
Incidentally, how do we know it climbed up FL430 (or whatever) after the transponder switched off? Was this some sort of height finding primary radar or information from the a/c itself.
I'm starting to think more and more that they are never going to find the plane. If its down that 4,000metre ridge for instance. How will they ever A). Locate the backbox and B). Recover? Once its signals gone- it could be ANYWHERE.
So for now for eternity the Pilots names will be blackened (well if the manufacturers etc are facing uncertainty they'll point to pilot error/interface wont they as 'probable' to protect their future sales opportunities.).
I have sent texts and emails from an aircraft when flying over Europe. OK it was at maybe 25k ft and not 40k ft but I sent and received texts perfectly fine and had a full signal. Also people were making voice calls and texting from the aircraft that crashed when the passengers overcame the hijackers on 9/11, so it is technically possible to use your mobile on an aircraft if you are overflying a mobile network. Also the aricraft was not equipped with an aero-mobile system. Radio masts do not 'point' in any direction. Radio waves radiate in all directions.
I still find it hard to believe that cabin crew can access the cockpit door in-flight despite what the Times says. You can't believe everything you read in the papers. Some airlines may have introduced rules, but it was not mandated as a result of the Helios event as far as i'm aware. It seems utterly pointless to have an armoured door if someone on the passenger side knows the code! I don't think even BA cabin crew are paid enough to sacrifice their lives.
Once its signals gone- it could be ANYWHERE.
I did hear something about possibly recover via passive scanning. I would imagine/hope that it is fitted with something similar to the [url= http://en.wikipedia.org/wiki/RECCO ]RECCO system[/url] used in ski/snow wear which reflects an incoming signal without requiring on-board power.
Radio masts do not 'point' in any direction. Radio waves radiate in all directions.
Hmmm.. They do look quite directional!
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[quote=imnotverygood ]Incidentally, how do we know it climbed up FL430 (or whatever) after the transponder switched off? Was this some sort of height finding primary radar or information from the a/c itself.
I'm fairly sure that's based on primary radar coverage. Military radar does often have some height capability (vertical arrays, or nodding), but we're not being told what it uses or how accurate it is, and I'd imagine we're unlikely to be told. Personally I'd take the accuracy of that height with a pinch of salt - could easily be out by 5-10,000ft. Useful info to know that it might have happened, but I wouldn't be placing to much reliance on formulating a scenario based on that (or ruling anything out because of it).
[quote=wobbliscott ]I have sent texts and emails from an aircraft when flying over Europe. OK it was at maybe 25k ft and not 40k ft but I sent and received texts perfectly fine and had a full signal.
You weren't maybe a bit lower than that, and flying a bit slower (as is often the case with European flights)? Or maybe an onboard transponder?
Also people were making voice calls and texting from the aircraft that crashed when the passengers overcame the hijackers on 9/11
That aircraft certainly was a lot lower and slower.
Radio masts do not 'point' in any direction. Radio waves radiate in all directions.
Radio antennas on masts very certainly do "point" and radio waves only propagate in all directions from an omnidirectional antenna. How do you imagine radar works if it's not possible to direct radio waves? Why do you think you have to point a satellite dish? I'll claim some authority on this issue as I used to work with radio systems.
Also people were making voice calls and texting from the aircraft that crashed when the passengers overcame the hijackers on 9/11, so it is technically possible to use your mobile on an aircraft if you are overflying a mobile network.
AIUI (from watching the film). They were using the phone system build into seats - which uses a satellite link off the plane.
Radio masts do not 'point' in any direction. Radio waves radiate in all directions.
Hmm, I can tell you're not a Radio engineer as people spend a *lot* of money making sure that antennas are directional. It's a very large and complex business. The measurement units of directionality, or gain, is 'dBi' which is [i]deciBels relative to an Isotropic antenna[/i]. An Isotropic antenna is one which radiates uniformly in all directions and is a theoretical construct as you can't actually make one...
If you still don't believe me, have a look here: http://en.wikipedia.org/wiki/Sector_antenna
NB one of my first jobs after graduating was working on the design of a re-spin of the BSkyB 'Squariel' antenna for Nortel. I did the matching circuit in microstrip in case you asked. Used to see them in the UK 20 odd years ago. It was highly directional, as had it not been you'd have never got a TV signal! http://en.wikipedia.org/wiki/Squarial
I did hear something about possibly recover via passive scanning. I would imagine/hope that it is fitted with something similar to the RECCO system used in ski/snow wear which reflects an incoming signal without requiring on-board power.
They are a pinger that starts transmitting when it enters the water. Relatively high frequency too so pretty short range underwater. If they were fitted active transponder instead then you could ping them and get a response.battery would last much longer too.
I did hear something about possibly recover via passive scanning. I would imagine/hope that it is fitted with something similar to the RECCO system used in ski/snow wear which reflects an incoming signal without requiring on-board power.
Passive scanning is pretty lossy, hence very limited range - similar to radar, you need a lot of power to cover an area.
Recco isn't quite a reflector, there are two antennas in the device and a diode (non linear element). The Search device sends out a signal on one frequency, which energises the first antenna. The diode, being non linear, create a harmonic spread, and the second antenna, being tuned to the wavelength of twice the original frequency, will transmit a week frequency doubled signal back.
The reason for the complexity is that it eliminates reflections, which would come back at the original 'search' frequency. If you pick 2x f coming back, you know there must be a RECCO device under the snow.
[quote=footflaps ]NB one of my first jobs after graduating was working on the design of a re-spin of the BSkyB 'Squariel' antenna for Nortel. I did the matching circuit in microstrip in case you asked. Used to see them in the UK 20 odd years ago. It was highly directional, as had it not been you'd have never got a TV signal! http://en.wikipedia.org/wiki/Squarial
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Ah - you trump me on professional knowledge of this (I've worked with people who designed antennas, but never been into that sort of thing myself - mainly modelling and protocol stuff, though a bit of real world propagation and coverage testing). I figured as much from your previous replies.
I note that I've always measured antenna gain using plain old dB units, and I think even those people who were proper RF engineers did the same, though it's kind of a minor point.
Passive scanning is pretty lossy, hence very limited range - similar to radar, you need a lot of power to cover an area.
Yep agreed.
Got to help when searching for a black box that has lost power and stopped transmitting though eh?
How did they find the black box form that French one mentioned earlier that took ages to find?
How did they find the black box form that French one mentioned earlier that took ages to find?
They found the wreckage using AUV's with multibeam and sidescan sonar. It took a while
I note that I've always measured antenna gain using plain old dB units
But dB is unit less, it's just a ratio. So they're just being sloppy and ignoring the 'i'.
In the RF world it's either dBm for dB milliwatts dBW for dB Watts (if referring to power), or dBi for dB relative to Isotropic for antenna gains. An amplifier can have a gain in dB as gain is a ratio (power out to power in).
[quote=footflaps ]
I note that I've always measured antenna gain using plain old dB units
But dB is unit less, it's just a ratio. So they're just being sloppy and ignoring the 'i'.
In the RF world it's either dBm for dB milliwatts dBW for dB Watts (if referring to power), or dBi for dB relative to Isotropic for antenna gains. An amplifier can have a gain in dB as gain is a ratio (power out to power in).
Nope - don't see why it's a problem, as unlike with dBm or dBW there isn't actually a baseline unit, what you're specifying is a ratio, not a quantity. The i is just a convenience notation rather than having the same significance as the m or the W (isotropic not being an SI unit 😉 )
I'm no expert in RF comms but I know enough to understand that radio waves do reflect off objects and the atmosphere which is why you don't need perfect line if sight for radio to work. Even radar that is focussed by a parabolic dish can be detected from a variety of angles - something the military exploits with great effect, the strength of the signal may be very weak and diminished, but it's there. When I've sent texts from an aircraft it may very well have been at a very low level, it was certainly after takeoff, so not a handful of feet from the ground, but my point is that it's possible.
I'm not so sure all the 9/11 calls were made from the on-board in-seat system. I've never known those systems to be even functioning when I've had a play with them and I doubt they are even installed on a clapped out aging American Airlines B757/767. Have you ever flown AA in economy? The last time I flew them in 2003 ish they still had roof mounted CRT TVs above the isle rather than individual seat mounted LCD screens. Their idea of inter-seat communication is a couple of polystyrene cups and a length of string. They're refreshing their fleet now, but back in 2000 they had a very very tired fleet.
The explanation I read was that in 2001 mobiles and base stations were more powerful, so had greater potential range. No idea if that's accurate.
I think in 11th sept 2001 the plane was flying low and slow whilst the baddies worked out what there next move would be.
The explanation I read was that in 2001 mobiles and base stations were more powerful, so had greater potential range. No idea if that's accurate.
Possibly true, the early analogue systems had better range in the UK. America always was different though and used their own systems e.g. Ignoring GSM for years and letting Ericsson and Nokia dominate the world market whilst US manufacturers just focussed on the home market.
The US analogue system, AMPS, was still in use in 2001: http://en.wikipedia.org/wiki/Advanced_Mobile_Phone_System
Actually my post above is wrong this [url= https://www.hsdl.org/?view&did=478665 ]report[/url] has the plane cruising at 35kft when the hijack occured and climbing to 41 k. Then diving. The calls are a mixture of in seat and mobile, they must have made the mobile calls somehow.
reading what passes for detail in the Aus Herald Sun pretty good chance got a fix of sorts on a black box 4500m down
goes back to reading aussie rules footie results
So have the Chinese found the needle in the haystack.
[quote=avdave2 ]So have the Chinese found the needle in the haystack.
It certainly seems quite likely, as it's hard to imagine what else the signal they're detecting could be from - unlike all the debris spotted - though I guess it's possible it's just their instrumentation playing up. If they have then that's quite incredible given the size of the haystack - you have to wonder whether they have some extra information.
you have to wonder whether they have some extra information.
Indeed, lets see if Sir Dickie trips them up.
If they have then that's quite incredible given the size of the haystack
would need to go and look for it (no that's not a joke) there was a quote from the Aus' guy running the search out of Perth that went something like "they say its like searching for a needle in a haystack - the problem is we haven't found the haystack"
think that Chinese vessel is pretty much state of the art technology
edit but it being in the right place can't be just luck
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That's a great graphic, kimbers.
following on from Kimber's graphic its pretty obvious that a guy in a snorkel mask will be the best way to find the plane
picture caption "A fast response craft from Australian Defence Vessel Ocean Shield tows Able Seaman Clearance Diver Michael Arnold as he searches the ocean for debris in the search zone in the southern Indian Ocean for the missing Malaysian Airlines flight MH370"
link to story and pics
http://www.theage.com.au/world/missing-malaysia-airline-jet-ocean-debris-would-depend-on-angle-speed-experts-20140409-zqsg6.html
Wow - two more hits from an FDR. They must have found the haystack at least. 🙂
interesting report in the guardian today about an unrelated incident, galley fire on a [url= http://www.theguardian.com/world/2014/apr/10/british-airways-jet-fire-re-ignited-crew-jumbo ]BA 747.[/url]
What makes it relavent to our discussion here is that the crew had difficulty putting the fire out with extinguishers, and did not follow correct procedures (ie not wearing oxegen masks, not electrically isolating the area etc) .
Which opens the mind to various scenarios on mh370.
[quote=toys19 ]Which opens the mind to various scenarios on mh370.
Well apart from the aircraft keeping flying for hours and making several controlled turns obviously.
The metal objects they've found off the coast of Australia aren't the plane, they are Rolf Harris' laptops.
making several controlled turns
This is supposition.
Well I suppose it is also supposition that the plane ever existed. I mean it's not like I've seen it with my own eyes - it could all be a conspiracy. I could just ignore all available information on that in the same way you appear to be ignoring the confirmed radar tracks and final location area.
I could just ignore all available information on that in the same way you appear to be ignoring the confirmed radar tracks and final location area.
I am not ignoring it, given that they have likely found the black boxes due to the pinger contact, I'm just wondering how it got there. Jeez you are looking for an argument/disagreement when there isn't one.
[quote=toys19 ]I'm just wondering how it got there.
Presumably it followed the confirmed radar track and then turned left once out of radar range and not needing to overfly anywhere else with radar coverage.
[quote=toys19 ]Jeez you are looking for an argument/disagreement when there isn't one.
I disagree that the confirmed radar track is "supposition"
no the suppostion part is that
implies that they were deliberate, and or nefarious.making several controlled turns
Well you suggest a plausible scenario in which the aircraft follows the confirmed radar track and keeps flying for several hours, where the turns (and subsequent return to straight and level) aren't deliberate.
"The metal objects they've found off the coast of Australia aren't the plane, they are Rolf Harris' laptops"
all the way from Henley on Thames ?
Well you suggest a plausible scenario in which the aircraft follows the confirmed radar track and keeps flying for several hours, where the turns (and subsequent return to straight and level) aren't deliberate.
Of course , it is most likely to be person or persons on baord deliberately crashing the plane.
I'm just trying to point out that outlier occurrences happen on aircraft, that is why we lose them. And the link I referenced above shows how despite the training and the protocols, people forget all that and make big mistakes.
I'm not looking for a row, merely a discussion of pissibolities.
[quote=toys19 ]I'm just trying to point out that outlier occurrences happen on aircraft, that is why we lose them.
They do, but not in this case. I'm not sure of the point in raising or discussing aircraft failure when it's so clear from the known evidence that's not what happened. Beyond reasonable doubt.
Beyond reasonable doubt.
Really? Convince me.