What the nine debris finds may tell us about the MH370 end point • Hacker News Board

Re: What the nine debris finds may tell us about the MH370 end point

#21

Post by nikanj » Sat, Jun 04, 2016, 1:34 PM UTC

lb1lf wrote: post #11

rbf wrote: post #8

Earlier quoted context omitted.

Or just continously upload the data to the internet, should be quite feasible these days with satellites everywhere.

>Or just continously upload the data to the internet, should be quite feasible these days with satellites everywhere. That would probably be a bit too much for existing satellite communication systems; while most flights wouldn't need to transmit such a signal most of the time (If a plane went missing over, say, the Midwest, we'd find it!), frequent transmissions from every flight over sea, for instance would probabl…

A quick googling tells me there are about 10000-15000 planes in the air around the world. GPS coordinates take less than 100 bytes, but let's give some headroom for plane ID, timestamp, etc.

That would mean about 1.5 megabytes per minute, globally. I think the global satellite network is easily up to the task.

Re: What the nine debris finds may tell us about the MH370 end point

#22

Post by Shivetya » Sat, Jun 04, 2016, 2:04 PM UTC

Mendenhall wrote: post #7

I keep thinking they need to put a black box on the top of these planes that auto ejects at the first sign of crashing and can float etc.

so how difficult would it be to have an autopilot system which can prevent off course diversions? As in, even when switched off it would prevent a plane from leaving a set area without ground clearance?

Re: What the nine debris finds may tell us about the MH370 end point

#23

Post by lb1lf » Sat, Jun 04, 2016, 3:19 PM UTC

nikanj wrote: post #21

lb1lf wrote: post #11

Earlier quoted context omitted.

>Or just continously upload the data to the internet, should be quite feasible these days with satellites everywhere. That would probably be a bit too much for existing satellite communication systems; while most flights wouldn't need to transmit such a signal most of the time (If a plane went missing over, say, the Midwest, we'd find it!), frequent transmissions from every flight over sea, for instance would probabl…

A quick googling tells me there are about 10000-15000 planes in the air around the world. GPS coordinates take less than 100 bytes, but let's give some headroom for plane ID, timestamp, etc. That would mean about 1.5 megabytes per minute, globally. I think the global satellite network is easily up to the task.

The raw data rate is pretty low, but keep in mind that there's all sorts of signaling traffic going on just to establish a connection, depending on protocol requiring multiple transmit/receive cycles - which in turn means waiting. Again depending on protocol, you may also have to handle collisions (more than one transmission in the same channel at the same time) etc - while still maintaining service for the network's regular customers.

Multiple short transmissions are more taxing than a few long ones.

Re: What the nine debris finds may tell us about the MH370 end point

#24

Post by lb1lf » Sat, Jun 04, 2016, 3:21 PM UTC

ricardobeat wrote: post #18

lb1lf wrote: post #9

Earlier quoted context omitted.

The challenge would be to make such a device fully autonomous while yet being safe; someone intentionally trying to fly the plane into the great void, never to be seen again is an exceedingly rare scenario. It is, however, an option such a tracking device should try to stay on top of. Hence, it would be best if the crew could not disable it. The problem with that design decision made, of course, is that it would be a…

These "problems" are already solved in black boxes. What is actually missing is constant transmission of GPS data through every flight.

The black boxes do not start transmitting until after the plane has crashed.

Also, I am pretty confident the crew can pull the fuse on the flight recorders if need arise.

Re: What the nine debris finds may tell us about the MH370 end point

#25

Post by Mendenhall » Sat, Jun 04, 2016, 3:42 PM UTC

Mendenhall wrote: post #7

I keep thinking they need to put a black box on the top of these planes that auto ejects at the first sign of crashing and can float etc.

I posted this and when I checked today it was great to see the thought behind all the responses. It really is a pleasure to read such educated opinions, specially since this sort of thing is not in my wheelhouse. Just wanted to say thanks to those who shared their information, I learn a lot from this.

Re: What the nine debris finds may tell us about the MH370 end point

#26

Post by james32322 » Sat, Jun 04, 2016, 3:55 PM UTC

ryanlol wrote: post #13

lloeki wrote: post #12

Earlier quoted context omitted.

You seem to be underestimating the extent of areas in the world where bandwidth is effectively zero in all practical scenarios

Iridium is available pretty much everywhere, you don't need much bandwidth to transmit your location.

Or use inmarsat which is available precicly everywhere. They have 100% world coverage.

Re: What the nine debris finds may tell us about the MH370 end point

#27

Post by patall » Sat, Jun 04, 2016, 3:56 PM UTC

Shivetya wrote: post #22

Mendenhall wrote: post #7

I keep thinking they need to put a black box on the top of these planes that auto ejects at the first sign of crashing and can float etc.

so how difficult would it be to have an autopilot system which can prevent off course diversions? As in, even when switched off it would prevent a plane from leaving a set area without ground clearance?

And once again, you gain a hackable component.

Re: What the nine debris finds may tell us about the MH370 end point

#28

Post by Mendenhall » Sat, Jun 04, 2016, 3:59 PM UTC

lb1lf wrote: post #9

Mendenhall wrote: post #7

I keep thinking they need to put a black box on the top of these planes that auto ejects at the first sign of crashing and can float etc.

The challenge would be to make such a device fully autonomous while yet being safe; someone intentionally trying to fly the plane into the great void, never to be seen again is an exceedingly rare scenario. It is, however, an option such a tracking device should try to stay on top of. Hence, it would be best if the crew could not disable it. The problem with that design decision made, of course, is that it would be a…

Does it make sense to you to perhaps not make it a black box, but basically just a "loud" pinger that can help you find the black boxes ?

I understand the vastness of the ocean but it just seems there has to be a way to at least get them quicker and closer to the original crash site, but I am ignorant of the technical side of such a thing as far as ranges etc.

Re: What the nine debris finds may tell us about the MH370 end point

#29

Post by msandford » Sat, Jun 04, 2016, 4:13 PM UTC

cm2187 wrote: post #17

lb1lf wrote: post #11

Earlier quoted context omitted.

>Or just continously upload the data to the internet, should be quite feasible these days with satellites everywhere. That would probably be a bit too much for existing satellite communication systems; while most flights wouldn't need to transmit such a signal most of the time (If a plane went missing over, say, the Midwest, we'd find it!), frequent transmissions from every flight over sea, for instance would probabl…

Over the midwest, the chances of survival are much greater than in the sea. Finding the wreckage immediatly is even more critical. Would a GPS coordinate every minute really be such a strain on the systems?

Make it every 5min or 15min and most of the technical problems drop right out. And it's still super useful for this kind of thing at 20% or 7% of the bandwidth.

Re: What the nine debris finds may tell us about the MH370 end point

#30

Post by lb1lf » Sat, Jun 04, 2016, 6:11 PM UTC

Mendenhall wrote: post #28

lb1lf wrote: post #9

Earlier quoted context omitted.

The challenge would be to make such a device fully autonomous while yet being safe; someone intentionally trying to fly the plane into the great void, never to be seen again is an exceedingly rare scenario. It is, however, an option such a tracking device should try to stay on top of. Hence, it would be best if the crew could not disable it. The problem with that design decision made, of course, is that it would be a…

Does it make sense to you to perhaps not make it a black box, but basically just a "loud" pinger that can help you find the black boxes ? I understand the vastness of the ocean but it just seems there has to be a way to at least get them quicker and closer to the original crash site, but I am ignorant of the technical side of such a thing as far as ranges etc.

The problem with a very loud pinger would be battery life; in order to be audible over large distances, it would require much energy and hence either work for a shorter time than today's boxes OR be heavier (which the airlines would hate for the added fuel consumption; in addition, the extra mass would make it harder to crash-proof it sufficiently)

The whole problem becomes a lot easier to handle if the boxes were more or less guaranteed to detach from the body and remain afloat; then they could ping a satellite and we'd know just where to look. That requires orders of magnitude less energy than transmitting an acoustic signal underwater.

(Such devices can be very small; the PLB I carry whenever I work offshore is the size of a slightly clunky cellphone and yet will let rescue services know my position to a few dozen yards minutes after I fell overboard - as long as I try to not do my man overboard-act too close to the poles, where coverage is spotty-ish.

Affix half a dozen of these loosely to an aircraft, be prepared to handle a ton of false alarms - and we'd know where planes come down at sea more or less instantly.

Matter of fact, it'd be so quick the first sign of trouble an airline was likely to get would be rescue services calling to ask whether they are SURE their flight such-and-such didn't crash at, say, 61 degrees 32'11.4752"N, 14 degrees 11'37.8531"W 47 seconds ago?