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Seven years on, what do we know about the disappearance of flight MH370? (2021)

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Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#411

Post by lxgr »

tjohns wrote: post #286
lxgr wrote: post #232

Earlier quoted context omitted.

These systems are using ADS-B and are only designed for operational/informational purposes so far, as far as I know. They are not used for air traffic control or other safety-critical purposes.

If it's using Iridum or (more likely) Inmarsat, it would technically be ADS-C. (There is also a parallel system that allows satellites to detect existing ADS-B signals, developed by Aireon - but this is relatively new and not used globally.) These absolutely can be used for air-traffic control. ADS-B has better temporal resolution than radar, and ADS-C is at least as good as manual position reports over the radio (us…

I believe GP was thinking about Aireon and similar systems, which are similar to ADS-C at a surface level, but solve a different problem:

ADS-C is a two-way communications protocol; ATC can request a certain update interval and I believe also boundary conditions requiring extra location transmissions. If that communication fails, both the ATC and pilot are informed about the fact, and they can reliably switch to other means of communications (e.g. voice position reports over HF).

> These absolutely can be used for air-traffic control.

ADS-B is (at least for now) mostly an augmentation of primary and secondary surveillance radar, as well as something to give other aircraft better situational awareness (via ADS-B in), as I understand it. I don't think either ATC nor pilots are currently relying on it for safety-critical decisions.

The big problem is that it's always possible for some plane's ADS-B transmitter to fail (maliciously or otherwise). On land, you have secondary or primary radar to fall back to.

This applies doubly so to third-party (i.e. non-ATC/non-AOC) satellite-based relaying services, since not only the ADS-B transmitter can fail in that scenario (and ADS-B was not originally designed to be received by satellites), but the relay service could fail as well, and the failure mode would be much less visible to both parties than in ADS-C.

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#412

Post by jszymborski »

interestica wrote: post #42
dml2135 wrote: post #29

Fascinating article. I had a chuckle at this excerpt: >The Malaysian investigators did look into whether the cargo could have started a fire, noting that it consisted mainly of ripe mangosteen fruits along with a small number of lithium batteries. Extensive attempts by the investigators to get mangosteen juice to react with the batteries and trigger a fire were unsuccessful. I'm sure plenty of people here have spent…

Investigations have some weird bits. I've always wondered if there's a certain title for the person who prepares the chickens for the 'chicken gun' in airplane testing. https://en.wikipedia.org/wiki/Chicken_gun

Obscure fact: Canada had a show called Royal Canadian Air Farce where, during their year-end special, they'd launch a "Chicken Cannon" at cut-outs of that years news makers.

https://www.youtube.com/watch?v=NLJ5q3-XJtQ

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#413

Post by hammock »

ianburrell wrote: post #281
mrandish wrote: post #182

Earlier quoted context omitted.

That scenario seems wildly improbable. First, the existence of the large U.S. airbase at Diego Garcia isn't remotely secret. As for an accidental shoot-down of an airliner before any visual identification or confirmation, I suppose it could happen but it goes against every policy and procedure the U.S. is known to follow. If an unidentified aircraft approached an airbase, they would scramble an intercept for visual i…

Also, there is nothing on Diego Garcia that could shoot down an airliner. There is Air Force base but it is all transports today with bombers in the past. There are no fighters based there and same was true in 2014. I couldn’t find any evidence of SAMs. The Air Force doesn’t believe in air defenses for bases outside of active war zones.

We had two carrier groups in the west pacific

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#414

Post by lxgr »

hallidave wrote: post #377
lxgr wrote: post #173

Earlier quoted context omitted.

Not sure what exactly you mean by "transponder coverage", but if you mean primary or secondary surveillance radar, this is not true for most of the Atlantic or Pacific. Radar (both primary and secondary, i.e. transponders) as well as ADS-B require line-of-sight, and oceanic air traffic control has to make due without that, which means operating either via ADS-C (i.e. planes self-reporting their position, autonomously…

Space-based ADS-B is now a thing. It is used for coverage of the north Atlantic. https://www.navcanada.ca/en/air-traffic/space-based-ads-b.as...

Yes, but note how this press release is mostly explaining what this technology could eventually be used for. I'm not aware of any ACCs actually using it for oceanic control today or having made an announcement of planning to do so in the future.

It's a very exciting technology, sure, but I think it's many years of testing and flawless operation as a secondary data source away from replacing ADS-C on oceanic routes.

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#415

Post by lxgr »

phire wrote: post #279
lxgr wrote: post #232

Earlier quoted context omitted.

These systems are using ADS-B and are only designed for operational/informational purposes so far, as far as I know. They are not used for air traffic control or other safety-critical purposes.

And for anyone who doesn't know; ADS-B is simply the aircraft voluntarily reporting its own GPS coordinates. So it's not going to help at all in a MH370 scenario.

> ADS-B is simply the aircraft voluntarily reporting its own GPS coordinates

True, but that is ultimately the case for all flights outside of primary radar coverage.

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#416

Post by lxgr »

dale_glass wrote: post #359
XorNot wrote: post #150

Earlier quoted context omitted.

I will say it seems utterly bonkers, given the cost of airliners, that we're talking about transmission costs on the order of minutes and not doing per-second updates. Admittedly a lot of this was before our new era of satellite constellations, but surely the future should now be "per second updates and streaming audio/video via satellite"?

Airliners are expensive, but satellites are even more so. Also there's a whole lot of air traffic.

You don't need one satellite per airplane, just like you don't need one base station per mobile phone.

Modern satellites can shift terabits per second. They can handle a lat/long pair every couple of minutes sent by every oceanic flight in the air comfortably (even when only using the L-band, which needs much smaller and simpler antennas than those used for in-flight Wi-Fi).

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#417

Post by Ajedi32 »

mariuolo wrote: post #407
Ajedi32 wrote: post #405

Earlier quoted context omitted.

It would be pretty easy to remove "kill everyone except me" as one of those options, if we thought it was worth it (which again, it probably isn't). Just mandate that an override switch for the life support systems be accessible in the passenger compartment.

> It would be pretty easy to remove "kill everyone except me" as one of those options, if we thought it was worth it (which again, it probably isn't). The idea is to keep everyone except the pilot alive but unconscious until things improve. I think it's preferable to everyone unconscious and eventually dead.

Uh... what? Whose idea, exactly? Because that's an absolutely terrible idea. Altitude-induced hypoxia isn't like some kind of controlled medical anesthesia. If all the passengers fall unconscious from it then it's neigh certain that at least some of them are going to die. That's why commercial airplanes have emergency oxygen masks for passengers, not just the pilot.

If both passengers and the pilot aren't being supplied with enough oxygen to remain conscious 100% of the time, then something has gone horribly wrong. If the reason passengers aren't being supplied with enough oxygen to remain conscious is because the pilot cut off their air supply intentionally, then that's even worse. (Though again, thankfully that situation seems to be extremely rare.)

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#418

Post by andrewaylett »

swyx wrote: post #274

apparently Ocean Infinity, the private salvage search company mentioned in the article that spent millions on a "no find no fee" search for MH370 is committing to doing it again this or next year: https://www.reddit.com/r/MH370/comments/t85bdv/ocean_infinit... how exactly do these guys fund themselves? this must be a horrendously expensive enterprise and fairly infrequent at that.

I suspect that like many peacetime efforts undertaken by various militaries, they need to train so they might as well do something useful while training.

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#419

Post by andrewaylett »

loeg wrote: post #221
InCityDreams wrote: post #16

Earlier quoted context omitted.

>tradition is to brave subzero air temperatures and water temperatures of 34 degrees Good read, but: all that detail and couldn't be bothered providing a (bracketed) degree-centigrade comparison.

If you don't know that 34F is approximately 1C, that's a you problem. It doesn’t require any mental math to observe that 34 is marginally greater than 32, which is the freezing point of water in Fahrenheit.

Why would I know that the freezing point of water is 32°F? Pretty much nothing in this country is measured in Fahrenheit.

I've definitely seen the comparison made, on random US articles which almost invariably show °C as well as °F, but I'm not sure that if someone asked me if I would recall the answer.

Re: Seven years on, what do we know about the disappearance of flight MH370? (2021)

#420

Post by loeg »

andrewaylett wrote: post #419
loeg wrote: post #221

Earlier quoted context omitted.

If you don't know that 34F is approximately 1C, that's a you problem. It doesn’t require any mental math to observe that 34 is marginally greater than 32, which is the freezing point of water in Fahrenheit.

Why would I know that the freezing point of water is 32°F? Pretty much nothing in this country is measured in Fahrenheit. I've definitely seen the comparison made, on random US articles which almost invariably show °C as well as °F, but I'm not sure that if someone asked me if I would recall the answer.

If you're even aware that Fahrenheit exists, this might be a thing you know. For example, my country mostly uses Fahrenheit but I know that freezing in Celsius is zero, because I attended school as a child.
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