'Contact lost' with Malaysia Airlines plane

[Destination]

You need a minimum of 3 to get a location.
You cant get a location without altitude, this is 3D space.

Altitude...
Yeah so you might be off by 4 or 5 miles.
In any direction, still a fair bit closer than 11 countries worth of Earth.
There would be two intersections so you'd have a north and a south search zone, but it wouldn't be that big.

 

[touch]

Altitude...
Yeah so you might be off by 4 or 5 miles.
In any direction, still a fair bit closer than 11 countries worth of Earth.
There would be two intersections so you'd have a north and a south search zone, but it wouldn't be that big.

You'd be a lot more than 4 or 5 miles off if you only had 2 satellites. The intersection of 2 spheres is a full circle and you cant limit it to ground level on the circle in this case.

Spoiler

The distance of the satellites away from the earth means that the circumference of the intersection is huge and small differences in altitude of the plane would make a massive difference in location.

 

[Jokester]

The circle has only two areas of real solutions though, at the North and South end as planes can only fly between ground level and ~40k feet

 

[touch]

The circle has only two areas of real solutions though, at the North and South end as planes can only fly between ground level and ~40k feet

Geostationary satellites are at 36000 kilometres up though. That means the radius of the circle which is the intersection between the 2 spheres is massive. Therefor it has a very shallow angle and small differences in height give a massive difference in horizontal location.

40,000 ft in height would give a difference of 964 kilometres horizontally.
It would be more accurate than what we know now, but far from the "4 or 5 miles difference" that i was arguing against.

 

[Destination]

You'd be a lot more than 4 or 5 miles off if you only had 2 satellites.

I think your reasoning is completely wrong.
They intersect on a sphere, they give multiple intersections which pass down deep into that sphere, the fact the altitude is such a short height in comparison to the other figures means it is barely noticeable.
As I said 4-5 miles either way.

 

[Django x2]

I'm heading to Inmarsat on Wednesday for some work. I'll keep my ear to the ground and see what the walls say. Doubt I will get anything useful though as I'm there in an IT consultancy capacity.

 

[Destination]

The Earth is a sphere also.
So your overlapping spheres are mostly inside the earth, not on its surface
The red points are the only points of interest.

 

[touch]

I think your reasoning is completely wrong.
They intersect on a sphere, they give multiple intersections which pass down deep into that sphere, the fact the altitude is such a short height in comparison to the other figures means it is barely noticeable.
As I said 4-5 miles either way.

The diagram i used to explain it is possibly misleading.

The diameter of the circular intersection of the satellite spheres is 3-4 times the diameter of the earth.

Here is a better diagram:

Spoiler

Blue circle is the Earth, the circle around it shows a 40,000ft flight level.
The large circle is the intersection of the spheres and the red line shows the difference an unknown altitude can make

 

[Beren]

Touch: I take it from your figures you have actually done some real navigation courses where you were taught spherical geometry?

The only thing that would seem to limit the search area noticeably using the satellite data would be to check at what points the plane would have started pinging a second satellite. And what range the plane would have covered from it's last known good point, and still be pinging just one satellite. AFAIK (which is not a whole lot)

Having driven on a fair few old airfields I suspect the idea that someone managed to land on a disused strip in a tropical country in a jumbo jet rather unlikely. You really don't need a lot of time for those strips to degrade horribly.

So I guess I am still in three scenarios - Plane lost at sea, Plane shot down by someone who is not admitting it, Plane landed on foreign soil. Basically still at square one after 10 days!

 

[Destination]

The diagram i used to explain it is possibly misleading.

The diameter of the circular intersection of the satellite spheres is 3-4 times the diameter of the earth.

Here is a better diagram:

Draw it again.
40,000 ft is 12kms
Earth's diameter is 12,742 km

You're diagram seems to suggest the flying height is about 1/10 the diameter of earth.

-edit then add a second sphere.
looks like you are out by a factor of 100

 

[touch]

Draw it again.

Read it again.

-edit then add a second sphere.

The large circle shows the intersection of two spheres.

 

[Energize]

I think the answer to that is along the lines of: How do you propose to 'triangulate' something using a single satellite?

AFAIK they've used the signal strength to get a rough estimate but that's all it is.

Well geometrically speaking, theoretically a return from a single ping can give all three spatial coordinates.

The angle of the return gives two of them and the return time the third, Doppler effect can also give some indication of direction. It's simply down to how good the technology is.

 

[Django x2]

To be fair Touch, your blue circle isn't even in the centre of the outside circle by quite some margin...

 

[touch]

To be fair Touch, your blue circle isn't even in the centre of the outside circle by quite some margin...

It's lucky i didnt base my aguments on taking measurements from the diagram then...

 

[Destination]

Read it again.


The large circle shows the intersection of two spheres.

Blue circle is the Earth, the circle around it shows a 40,000ft flight level.

This is your text.
A 40k FEET level isn't remotely close to where you have drawn it.
A 40k level is virtually the same level as the height of the Earth.
49k Feet is 12km, Earth's diameter is 1000 times this.
Your blue circle should be 1/1000 larger than your Earth circle.
Thus bugger all length of red line, as I stated.

 

[Tuppy_Glossop]

I'm really hoping for some exceptional diagrams now

 

[stulid]

Think its lost - http://beforeitsnews.com/alternativ...ttp://b4in.info/aUDb&utm_medium=facebook-post

 

[touch]

Thus bugger all length of red line, as I stated.

Ok then. Your turn.
Show how a difference of 40,000ft corresponds to only 4-5 miles horizontal difference.

 

[Destination]

I'm really hoping for some exceptional diagrams now

This is a crap one, as the geostat's are 6 times as far from the earth as the distance of the earth's radius, and the maximum variation in height above this radius is less than 1/1000 of that radius, knowing height although useful isn't necessary.

They already gave us this diagram, with one line on it, as they had only one satellite data to go on.
The point was raised if they had a second, then things would be rosy, as the lines would intersect, indeed they would, it would give 2 places, one north and one south to search.

Someone suggested you need to know height, and yes, it would be helpful, but the search area would be narrow.

The lines have a finite width, this is the search areas, the finite width is governed by the potential variation in the planes altitude, and the sensitivity of the equipment measuring.

They are not thousands of KMs wide.
Most the proposed intersection made by a second satellites beam can be discounted as it occurs either in space, or below the surface of the Earth.

 

[Destination]

Ok then. Your turn.
Show how a difference of 40,000ft corresponds to only 4-5 miles horizontal difference.

It does if a second satellite was added to the equation, which it has not been, but was suggested when someone said you can work with two, and you stated you cannot, you need three.
Three would be helpful, but two would be very workable.

The satellites are equatorial, they rotate with the Earth, they are fixed position.
The entire debate is moot, as there is only one satellite, thus why they are searching along hundreds of Kms of length.