I think most of us realise that the 40 deg arc is an ambiguous position line with a margin of error quoted as up to+/- 50km.

Pedant Mode
 

Radials radiate. These were arcs subtended by the radial.

Like VOR, is a Radial device and wrongly identified as Range :)

The transponder response does have the aircraft ident embedded in it, a techy even told us how it is transferred to a replacement box and what equip is used ( it can only be done if aircraft logic shows ground nor air.

However who on the ground can see or access that data in the return I don't know.

The difference between pressure altitude and true height is D-factor.

From memory a D-factor in the far east IRO 2,000-2,500 feet was usual.

But even if the crew is overcome by smoke, hypoxia, etc - then there's the question of how the plane stays in the air for seven hours with a fire burning in the hold.

- I take it then you do not subscribe to the current search area (on the 40 degree arc) having started in the South China Sea on the same arc? Perhaps you have another theory as to how it went from one to the other while appearing to be on the '40 degree' arc with 7 hourly signals all at that elevation? Pontious - I assume the same? - You do not believe it went down to the South Indian Ocean off Aus either? By the way, these arcs are NOT subtended by 'radials' but by position lines.

Thank you, Lonewolf - I have always been suspicious of 'co-incidences'. We will share the eyebrows.

Yes, everyone, I do understand the margins of error (as yet unknown) on this '40 degree arc', but I still reckon that the odds of the a/c tracking ACROSS the arcs and at least one ping being at some other angle would be high.

Are we to assume from the sketchy info so far that the 'elevation' of the first ping after comms loss (supposedly Malacca) was the same as the previous (north of Malaysia?).

fg - thanks for PM - don't forget we (some) are assuming the a/c WAS on that arc when it supposedly crashed - co-incidence?

New Chinese Imagery
 

Excuse the interruption, but don't you think the new satellite photo just released looks a tad like an evacuation slide......?

a bit large though, at 22m x 13m.

Should planes be fitted with something like this in an 'inaccessible in flight location' (maybe on the tail fin) http://www.globaltelesat.co.uk/satph...Messenger.html

It's a GPS tracker that can report it's position by satellite every few minutes (5 / 10 minutes would probably be good). Would probably also be useful for oceanic ATC.

[I am aware of the project to have satellite based ADS-B recievers]

It was seen on malay and Thai mil primary radar and the Malayasia track was confirmed later

If you think mil radar will not pick up unidentified planes please explain why they have them!

A very valid point, why would anyone navigate along a route exactly the same distance (elevation) from a satellite?

Almost any route of any distance, great circle or compass would cross "arcs" as you say.

Even if the currents were at a leisurely walk of 3 Knots x 24 hours in a day (currents never sleep) = Debris Field 72 miles from ditching / impact in just one day

It is now going on 15 days since MH370 went missing

15 days x 72 miles = 1080 NM from ditching / impact

Now going back to basic pilot trainer class if you are one degree off course in 60 miles you will be one mile off course.

1080 / 60 = 18 miles plus or minus the debris field could be located with just one degree change in the ocean currents vs. those who plot the currents.

All of these numbers could be multiplied by two or three with all the verbals in the Southern Indian Ocean.

Apart from hypoxia, are there any other scenarios that would account for the crew and passengers being incapacitated AND the plane being able to fly for another 5-7 hours?

Military Primary Radar is 3D since the 1960. They beam both in azimuth as well as vertical. The altutude capturing capability is usually quite good, but it needs to be calibrated from time to time. Also it shows geographical altitude, not barometric, which in older systems could be a pain in the backside when trying to correlate own primary targets with civilian secondaries. Software changes later life was good again...

- er, no. The Inmarsat data was not known at that time. You need to revisit the timeline. - this is difficult! A massive search effort is being expended ON THE 40 DEGREE ARC at supposed fuel exhaustion point. Inmarsat tell us the pings were 'all' at 40 degree elevations. Since we know where the first ping was transmitted (roughly), please explain how it got to the SIS, pinging at the same elevation all 7 times without tracking along the arc? - you obviously believe the reported radar data. Confirmed???? By whom? I have not seen these statements stand questioning.
- read the posts in this thread and you will see. Half+ the mil probably asleep at the wheel at the time. Oh, do ask the Russians who popped a Badger up in the Firth of Forth a few years back....................... :-)

Current military primary surveillance radar DOES provide altitude
 

For all who think that primary radar cannot indicate altitude, please look up the SPS-48 - which entered service in the U.S. Navy over 50 YEARS ago and is just a typical example of a long range 3-D radar type.

Phased array 3-D surveillance radars are common in military air defense service as we really don't like to just have interceptors go wandering around trying to determine if the bogey target is at 10K or FL450.

Now, the fair point here is that the height accuracy is definitely affected by the target range, but less than ~4K foot altitude error at 200 nm range is definitely common.

(Lonewolf50 - I was on the design team for the NTU many, many years ago. It's good to see it spoken of well.)

The 40 degree arc is based upon the altitude of the plane at the LKP. That's why the satellite polling the device terminal has to contain altitude data. The physical radius of the radio waves (the band) is limited. So if the polling has the wrong altitude the signal will miss the plane entirely and the connection is going to be dropped. So a difference in the arc implies a difference in the altitude of the plane and nothing more. Moreover, since the polling take place only once an hour it only tells us something about the altitude of the plane at that precise moment in time, not what happened in between.

- no. Little to do with aircraft altitude. Forget altitude. Covered in depth in previous posts. You need to compare geo-stat orbit distance with 6 nm to see.

Re Satellite imagery
 

Just watching a BBC News interview with David Mearns (Blue Water Recoveries Ltd), expert in marine recovery. He was describing where the search may be directed now, assuming drift, and comparisons with the locations of the Australian and Chinese imagery. Also using current information to work backwards to calculate a predicted area for any original ditching.

When asked that all this assumes the material photographed is positively identified as part(s) of MH370, he implied the Australians and Chinese would not be chasing things likely to have another obvious origin.

If I understand the complaint correctly, the complaint is based upon a fundamental error. The 40 degree arc that is plotted on a map is a two dimensional representation of a three dimensional reality. There is no claim that the plane moved along the 40 degree arc in two dimensional space, only that it moved along the arc in three dimensional space. If every ping happened along the 40 degree arc all the means is that the plane held to the same altitude for 7 hours, nothing more.

Either that or I do not understand the criticism.