Blueyonda

Ocean Shield disappeared for while on marine traffic but I see it is a few hours out of Albany at this time. Google marine traffic. It is a fuscia coloured hull.

Red Plum

Why just to the point of no return? If you think about it a little more, what will be it's 'point of no return' once it operates from a ship? That said it could well 'hop' from one deck to another as stages however there are difficulties with cross operating with other nations' ships.

Having spent a couple of thousand hours operating from ships with 'non-diversion' flying you work with 'Mother' being your destination!

Unixman

Anybody know if HMS Echo has arrived in the search area yet? Gone very quiet on that front.

takata

Official news about today search here:
http://www.amsa.gov.au/media/documen...a_Update25.pdf

Golf-Mike-Mike

It's fairly simple fuel endurance maths to know when a helicopter could leave the 'mother ship' before the ship gets to the new search area, operate for an hour or so in the search area (guided by co-ordinates from RAAF/AMSA/RNZAF), then return to the ship which by then would be a few miles nearer too? But I guess you're right in the need to consider alternates as well.

lpatrick

Unixman, HMS Echo still en route according to Belfast Telegraph.

Big Toe

Updates on Ocean Shield position from Marinetraffic.com
OCEAN SHIELD - Offshore supply ship: current position and details | IMO 9628374, MMSI 503728000, Callsign VHEH | Registered in Australia - AIS Marine Traffic

Coagie

I think the final "partial" ping was partial because of a bad signal between the satellite and the aircraft, because the aircraft may not have been straight and level at that point, thus putting it's antenna in a non-optimum position, rather than the ping being cut off in mid signal due to the plane sinking in the ocean.

Pontius Navigator

Coagie, all things are possible. It would need an AOB over 50 degrees (I guess) for airframe blanking followed by a recovery so the antennae could see the satellite.

TxAggie94

I've never been clear on the "partial ping"...was it the satellite system pinging the aircraft or was it a message initiated by the aircraft's satcom? I've been assuming the later, but...that would mean that "ping" is not an accurate term. Or at the least, the final ping is quite different from the other pings. Yet, I continue to see it referred to as a "ping".

misd-agin

AAKEE- 3500, and perhaps 4000 nm, would be a reasonable estimate.

Optimum performance would start at approx FL 380 and increase as the aircraft weight was reduced with fuel burn off.

Range at very low altitude would be around 60-70% of it's high altitude range but the endurance at low altitude would be very similar (90-95%?).

RichManJoe

From what I can infer from the comm protocol, the partial ping was initiated by the aircraft. I won't speculate on why. The satellite did not know to initiate the ping.

IMHO:

The partial ping can be analyzed for doppler and that might give some indication of position. However, since only one satellite is involved, this would produce a curve of possible positions, with an associated uncertainty, not a point.

Unless there was a complete handshake with the satellite (ie. aircraft sends ping to satellite, satellite replies, aircraft replies) timing data would not be generated, so one can not calculate a corresponding curve for aircraft position due to timing.

I have not analyzed the time and doppler information (don't have the proper tools in place and would take to long to generate - would rather work on my boat), but from experience on other systems, these might create somewhat orthogonal or independent curves which at their intersection would produce a position. Just speculating.

Ian W

The aircraft systems logon to the satellite(s) by calling them first then they are polled at intervals to check that their receiver is still ready and the low level link is still good. If the aircraft system thinks it has lost the signal - say due to a power down then back up - it might try to restart the lost link. As this last ping was from the aircraft and out of time, it is possibly another log on attempt from the aircraft system that was interrupted.

hamster3null

Consider the following.

Doppler shifts are measurements of "radial speed": speed with which the aircraft is getting closer to or further away from the satellite.

If you have a bunch of speed values and you assume that the trajectory is reasonably smooth (no zigzagging), you can calculate the change in radial distance (ie arc) by summation of speed*time.

In other words, if the aircraft is moving in a smooth manner, Doppler shifts and arcs are not independent sources of information. You can fit a number of trajectories to the Doppler shift curve, but, as long as they fit, all points always end up on the same arcs. The unknown is the transverse speed and the transverse distance traveled: how far along each arc your points end up.

So, if we take the previous search point and recalculate the trajectory using lower speeds, all points move northeast and the point of last transmission moves northeast quite a bit, while staying on the ~40 degree arc.

If you look at my spreadsheet a couple of pages ago, I had possible Southern routes worked out for 400 knots and 450 knots, and the results were as expected: going from 450 to 400 moved the endpoint 4 degrees north and 5.5 degrees east.

FE Hoppy

Of course the assumption that the final range was based on fuel starvation could be false in which case you have a wider search arc.

ekw

So if a bus disappears off a deep ravine you would be prepared to suspect all causes except the driver? Your position is illogical. Any cause which has not been eliminated must stay in the running. Most rational people can distinguish between speculation and fact. I concede that large sections of our media do blur the lines at times, but that is in their nature.

JamesGV

The satellite/satcom provided the "pings".
Doppler analysis provided direction.

What process/data provided fuel burn/speed/altitude calcs ?
Must have missed it.

500N

So, a new day, is it today that we will get some recovered "something" ?

IF something is recovered from the aircraft, we will get another media storm.

If they don't find something by Sunday evening AEST, I question if they will.

Chronus

I find it surprising that the US Navy has not tasked an aircraft carrier to assist. The avialbility of such vessels would greatly assist by substantially increasing time over the search area conducted by carrier based aircraft.

Perhaps some on this forum with better knowledge of US Naval fleet ops could enlighten us.

hamster3null

I tried to recalculate the northern route as well using lower speeds (400-420 kts).

At all speeds, it slices off a bit of Eastern India, goes above Himalayas between Nepal and China, and terminates in Tajikistan or Kyrgyzstan.

Below 420 kts it may never even get out of the mountains: there's a pretty formidable and desolate mountain range with peaks up to 23000' across the route along Tajikistan/Kyrgyzstan border, right in the area where the "partial ping" could have come from at 400 kts.

I know, I know, "how come no one saw it on the radars?" Suppose that Indians missed it for whatever reason. Nepal has no radars and even no air force. The rest of the way is over pretty rugged terrain, mostly above 15000'. My routes even pass in the vicinity of K2. We already heard that the aircraft flew lower than normal (FL295) in the Straits of Malacca. Flying FL295 in the Himalayas could significantly limit its exposure to radars.

The biggest thing I don't like about this is that slower routes take it into the southwestern corner of the Tibetan Plateau. It's still pretty desolate, but it's flat and the aircraft could be visible to Chinese military radars if there are any in the vicinity.

P.S. If you think that Tajiks would have reported a big aircraft crashing into one of their mountain ranges or at least would have gone to look for it, then a) the area we're talking about looks roughly like so http://www.panoramio.com/photo/49758018, and b) Tajiks have bigger problems than looking for other people's lost aircraft: http://en.itar-tass.com/world/725561