Geosynchronous vs. Geostationary
 

There are 2 operational INMARSAT satellites that were within view of MH370 at various times. A 3rd satellite, INMARSAT-5 F1 was launched in December 2013, but is still undergoing on-orbit tests until mid-July 2014, per Slide 18 of:

http://www.inmarsat.com/wp-content/u...ation_2013.pdf

Nit-picking a bit, the satellites are geosynchronous, not quite geostationary. Hence their latitude and longitude will vary slightly over the day, typically tracing a figure 8 on the ground. See Figure 3 in this page by T.S. Kelso:

CelesTrak: "Basics of the Geostationary Orbit"

Note that the figure 8 is for a satellite whose orbit has eccentricity of zero, whereas non-zero eccentricity distorts the figure 8 somewhat.

Kelso lists orbital elements in TLE (two line element) format here:

http://celestrak.com/NORAD/elements/geo.txt

This is the active one for the Indian Ocean Region:

INMARSAT 3-F1
1 23839U 96020A 14077.02691924 .00000003 00000-0 10000-3 0 2792
2 23839 1.6580 73.1420 0005562 281.9751 254.5647 1.00273339 65760

Element 2 in Line 2 is the orbital inclination in degrees, in this case 1.658 deg. Thus both the latitude and longitude will vary a bit over a day, tracing a sort of figure 8

Element 4 in Line 2 is the eccentricity, with an implied decimal point at the left. The eccentricity is 0.0005562 for this satellite.

The N2YO website uses the TLE data to compute present position of the satellite:

LIVE REAL TIME SATELLITE TRACKING AND PREDICTIONS: INMARSAT 5-F1

The Pacific Ocean Region satellite is INMARSAT-4 F1.

Kelso's TLE data:

INMARSAT 4-F1
1 28628U 05009A 14077.46405487 -.00000269 00000-0 10000-3 0 3195
2 28628 2.6638 355.1900 0002955 355.6954 135.5891 1.00271237 32824

Inclination is 2.6638 deg, eccentricity is 0.0002955.

Tracking data from N2YO:

LIVE REAL TIME SATELLITE TRACKING AND PREDICTIONS: INMARSAT 4-F1

The latitude will range between plus and minus the inclination angle over one day.

Will attempt to calculate and post the latitude and longitude of both active satellites for the hourly pings.

The search agencies have certainly done this already. Which may be why they have plotted the circle for only the last ping, so they don't get bogged down in explaining to a low tech press pool why the circles aren't concentric.

RE: "Better still are you sure it wasn't a UFO he saw and decided to just go on a bit of joy ride, yeah, let's make sure our plan B includes a good swath of Malaysia and just for giggles we'll turn off the transponder. That'll put the meteorite/UFO/bigfoot off for a bit"

Just sayin... there could be a less-than-super-duper-brilliant Plan B in the FMS. That could have the left turn, and be what the investigator leakers are seeing.

Plan B becomes active when executed. An emergency is the reason. Not necessarily UFOs or BigFoot. Maybe from smoke. Or electrical mechanical malfunction. And the comms and transponder fail then as well as ACARS. and off we go (left) on AP.

"The problem with this though is it conveniently ignores some parts of the data that just don't fit. Such as the voice radio transmission sector change acknowledgement AFTER the transponder was shutdown, etc."

Some of the problems we are having, is that we have to few facts, and to much fantasy and theories.

How do we know the transponder was shut down before last voice transmission?

Depending on the failure they faced, we do not know what systems that would have failed.

Wa wa
 

The Malaysians have not confirmed a last waypoint as such, but have definitely given the last position that their primary radar tracked the plane to as 320km north west of Penang. You can get that information from the New Straits Times.

Thailand have belatedly corroborated the primary radar data, though they are not giving details.

Would it have been possible to get from the area of the Maldives where an aircraft was spotted at 0615, to, say, Iran or Pakistan, on the red northern ping arc by 0811 when the last ping was received? Would the aircraft have had enough endurance and speed for the transit?

@Blake777

If Thailand had released this information earlier, almost an entire week of search and rescue efforts in the South China Sea could have been avoided. I think this just goes to show how suspicious most of the countries in this area are of each other.

In any case, MH370 apparently had a second Flight Plan (Plan B).

And it can be "executed" quickly and easily in an emergency (or by accident?)

Wouldn't it be nice for Malaysian officials to tell us what that Plan B has, waypoints, turns, destinations, and from what source???

Let me offer the view of someone with experience of North Atlantic open sea SAR (10 years).
It doesn't surprise me that they haven't found anything yet, because the search area is enormous, and the further away in time we go, the higher the uncertainty. Also, finding stuff in the sea is very difficult, even with Radar, IR, etc. It depends on weather, sea state, what sensor you are using, what you are looking for, etc. Remember than in the AF case there was a relatively good fix on their estimated position, here we are talking about searching (almost) a whole ocean. If the a/c flew for 7 hours, we don't have any idea of where it went, the uncertainty is huge, it's a nightmare from a SAR point of view.
Also, you have to understand something called "Coverage Factor".
When you do SAR, be it with airplanes, helis, or even ships, each Search Unit has a "view range" (it can be visual, radar, IR, whatever), over which it won't be able to detect anything - the technical name is "sweep width".
Now, when you have a small search area, you get the SAR vehicle to cover it with a given pattern (there are several types), in such a way that its track guarantees that the whole area is covered by the area "drawn" by the sweep width as you move along:
http://navyflightmanuals.tpub.com/P-553/P-5530149im.jpg
That's the figure to the right, which has a coverage factor of 1.0.
In the previous picture, notice the pattern on the left, because in that one, the coverage factor isn't 1.0, it's probably 0.5 or something like that.
When you cover huge areas (such as this case of MH370), if you aim for a CF of 1.0 you need lots and lots (and lots and lots!!!) of search units, which costs lots and lots of $$$, so what is usually done is simply to use math and get CF of between 0.5 and 1.0, according to several factors. You actually don't cover the whole area, you go through it with "gaps" to make sure you pass over it as quickly as possible, because as time goes by, the search area increases (due to uncertainty caused by the wind, sea currents, etc). So I'm sure they aren't using CF of 1.0 to cover the whole Indian Ocean, I think maybe not even 0.5...
If you realize that they are now searching in an ocean area that goes from India almost to Antactica, it's no surprise that they haven't found the a/c yet, assuming that it crashed into the ocean after 7 hours of flight, and it's also the reason why the conspiracy theories are growing.
Call me a pessimist, but as time goes by, the odds of finding debris go down, and with a search area this big, I find it possible (not very likely, but possible) that they'll never find anything... That is assuming, as I do, that the a/c had an emergency that incapacitated the pilots and the plane flew for hours until it ran out of fuel (I don't buy the media hype, sorry, if you have a strong electrical fire and you start to shutdown systems, your priority is not talking to ATC).
Either way, this is only me speculating on the limited information we have so far, and most of it filtered by the media.

As for the mid air intercept and subsequent formation there are plenty of products out there that work with an Ipad and allow reception of other aircraft ADS-B data, so no need to turn the aircraft transponder on. Just two examples are shown below, one of which also has an AHRS ability!!!

There is also a lot of navigation apps available for Ipad that would allow someone to accurately fly a predetermined route just using the aircrafts HDG control.

XGPS170 - GPS + ADS-B Weather and Traffic Receiver for iPad and Android Tablets | Dual Electronics

iLevil - ADS-B AHRS GPS

Nope.
No, it would not. A carrier group can send up a fighter to see who the hell it is.
Capt Rogers didn't have a VID. (He was also in a little surface action with Iranian patrol boats, which also isn't something a US CV has been doing lately).
Most importantly, US Navy ship CO's are taught a few lessons about that little thing that Vincennes did as they go through their command track. ;) (It's a case study. :ok: )

Wolf, my fellow lupine, that was not even a nice try. :sad:

Not to mention there wasn't an American warship within a 1,000 miles of the southern end of that arc.

W&F,

You and others promoting the silly "shadowing" idea need to learn about formation. If SQ was minding its own business cruising at M.84 ish and our hero, unaware of SQ's take-off time were 12 minutes off, it would take 1800nm to catch up using Mmo on MH370's T7. You can only "make up" 24 nautical miles an hour, that's the speed differential between normal cruise and Mmo on the T7.

Speaking of facts and questions...

CNN's Richard Quest (to whom I tweeted a question on this) just said on TV that his understanding "from US officials" is that when ACARS "reported in" at 1:07, it communicated to ground the "next 2 waypoints"...

...one of which is presumably this "pre-programmed left turn" AWAY FROM BEIJING

If this is Flight Plan A (A for Active) why is KL ATC not saying,
what? huh? where are u going? come again???

Suction feed of fuel on RR engines
 

This quote from Flown-It at post 5871 five pages back, at 18th Mar 2014, 21:50
My buddy flies the 2ER and emailed me the fuel management system manual; I'll try to wade through it and figure it out for you. Just in general: the system is set up with (roughly) 26,000 gal in the center tank and 9,300 gal in each wing tank. Center has two fuel pumps, one for each engine, and each feed line tees into the line from the wing tank on that side. The center pumps are at a higher output pressure than the wing pumps, so with both center and wing pumps working all feed is from the center tank. If center pump is shut off and wing either fails or is shut off, then suction, but only from the wing tank apparently (at least, as far as I have deciphered). The entrained air in the fuel has been known to restrict power output and cause reverse flows through the compressor when the pump(s) are off, until all the air in the fuel is gone, so the drill is to run with all the pumps churning away, at least until center is reduced or empty.

From that I draw that after the fuel gets cold and the entrained air is finally gone, it should siphon just fine. At that point, likely not altitude dependent (although that is my surmise, and not from the manual).

AMSA media release of this morning

https://www.amsa.gov.au/media/docume...H370search.pdf

merlin driver:

Yes, excellent points concerning SAR, thank you, I am aware. However the objective at that point in my little exercise was to determine which was the greater of two possibilities; aircraft/aircraft system failure or hijack. If aircraft/aircraft system failure I assigned a high probability that the crash would be within a reasonable distance of last known position and 10 days of high coverage SAR in this space under this scenario should turn up some wreckage, it did not. Thus, all I am saying is that this fact makes the probability of a hijack greater than that of aircraft failure

keeping SATCOM up makes perfect sense
 

@Ornis
@D.S.

Here is why network links are kept up. Suppose you have a scenario generating LOTS of ACARS messages in succession (e.g. AF447). If each message has to set up and tear down the link there is tremendous overhead added. Just setting up and tearing down a connection involves the exchange of a bunch of messages. When networks are designed a lot of attention is given to the most efficient use of resources to meet the design objectives of the network. We can rest assured that the keepalive ping is actually very efficient use of the sat link.

Just think how handy it is to have a SAT link up, whether you need it or not, all for the low, low cost of 1 ping each hour!

By the way, the computer you are reading this on is sending periodic keepalive messages so it can keep using the network address it currently has been assigned (assuming you are using DHCP and not a static IP address). It wants to avoid the extra headache of having its address expire and being forced to renew it. This is a very, very common practice in networking.

Useable Fuel?
 

I'm not aware of the fuel setup on the 777, but assuming it's like others I do know, is this possible, either on its own or in combination with other circumstances?

In aircraft I do know about, this is a possible scenario that came too close, far too close, to happening.


A) Aircraft takes of with fuel in both wing tanks and centre tank with all boost pumps on.

B) Due centre pumps having higher pressure they override the wing tank pumps and both engines feed from the centre tank.

C) Once all the fuel is used from the centre tank the wing tank pumps automatically take over as they have higher pressure then the now empty centre tank pumps.

D) Aircraft I am familiar with can suction feed from the wing tanks but not the centre tank.


Is it possible that the aircraft took off with the centre tank pumps not turned on?

Result, Everything is normal until the wing tanks run out of fuel at which time the engines EGT rapidly drops and due no engine-generator, electrics to power the centre tank pumps they don't work and as the aircraft cannot suction feed from the centre tank altitude is rapidly lost until such time as the aircraft makes contact with the ground after running out of fuel with the centre tank still full?

If one were to tail another aircraft's radar shadow not only one needs military pilot skills especially when flying in the night (when one can possibly only see the tail lights or wingtip lights only) but also have the communications systems in "ON" mode to receive updates on exact flight path of the aircraft ahead. Given that all such equipment were switched off - this seems too unlikely.

Put it in your flight planner from where it went missing then was sighted (if it was sighted ) in Maldives from where it was last known and you end up DIRECT LINE TO Somalia.

Why did the US Navy ships stop looking and go West with 7th fleet.