Malaysian Airlines MH370 contact lost

[GarageYears]

Originally Posted by GarageYears
I keep seeing questions related to why the SATCOM system was sent pings, etc, and discussion related to ACARS use, MAS subscription to the ACARS reporting service to Boeing (or not), but isn't it also the case that the SATCOM transceivers at ALSO available for voice comms?

Yes, 777 cockpit SAT comms out of the tin, and optionally, in-seat passenger satellite linked phone service.

Ah, thanks for the confirmation.

Right, so that puts to bed the occasional "well-if-they-aren't subscribed to Boeing's data monitoring... why does the satellite ping them" comment I've seen. The pings are there just as much for the cockpit voice comms link, as any data that may or may not be sent over the same link.

[Heli-phile]

Deriving the course from the Inmarsat pings

So what you have done is say you cannot join the dots if there is only 1 dot..... OK

[mm43]

That last PING arc.

There still seems to be confusion over the 40° elevation angle arcs accredited to the last 'ping' timed by the Inmarsat IOR at 64°E over the equator.

The graphic below should provide insight into how that elevation relates to any angle subtended from the earths center in any plane. Note the graphic doesn't indicate the top or bottom of the earth sphere is North or South, as it could equally be 154°E or 26°W. Also, from 35,768km above the equator, the full disc is not seen, as reference to the graphic will show. 90° elevation is on the beam centerline, but at an earth elevation of 50° the angle subtended from the center of the earth is 35° and the angle at the satellite is 5° of its overall half beam-width of 8.7°.



When plotted on a transverse Mercator chart/map, the ring drawn will start being circular immediately below the satellite, but as the angle gets bigger the Mercator projection makes the projection elongated in a polar direction. If drawn on a equidistant projection, the circles would remain just that.

Those who have referred to the AMSA search graphics will note that the tracks supplied by the NTSB are based on two different ground speeds, and they reproduce the diverging tracks. The track indicating the faster speed is the westward one.

[GarageYears]

For me this looks like there has been failure situation / slow decompression or problem with Oxygen for crew, they might have started diversion, altitude change, possible some issue with the Avionics, I don't know the T7 systems, so can't comment on details of this.

At one stage they have BOTH become incapacitated, and descended in altitude, flown on until running out of fuel (Similar Helios)

What exactly caused this to happen, none of us can only speculate in, but what is important is to create the most likely scenario and work with this.

Most such scenarios it will the most simple and least spectacular version that will be the truth.

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.

Unfortunately it doesn't seem what is postulated is the simplest solution to all the information that we know, even if that answer isn't one that we'd like it to be.

Coming up with a half-baked hypothesis (and I'm not trying to insult anyone here) and suggesting the plane flew off in the murky blue yonder for 7 hours or so until it flamed out, doesn't seem to fit with the last radar track point and the INMARSAT ping arc.

[500N]

What are all these photos turning up in the media of jets in the jungle.
jets under the water "showing" wings and windows ?

Have they all been debunked and the media just using them to sell newspapers ?

[FlightDream111]

Range can be extended by lowering cruise speed?

The Malaysian government has released an image showing maximum distance aircraft could have travelled - is this based on range at cruise speed or less?

As far as I know, range can be extended by flying at slower than the typical cruise speed listed as 490 kt?

What is the best range speed?

Speed
The speed which gives the maximum range for a given aircraft weight and altitude is called best range speed. Flying at higher speeds than the best range speed increases the drag and the fuel flow, and therefore reduces the range. Lower speeds than the best range speed reduce the drag and the fuel flow, but they also reduce the distance traveled per time which is more dominant, and therefore reduce the range.

SKYbrary - AP4ATCO - Factors Affecting Aircraft Performance During Cruise

[Graham321]

Waypoint programmed but not executed.

For direct access to my "nearest suitable", I have often pre-programmed (but not executed) a "Direct to ABC" and sat there watching a dotted pink line with an accurate track arc peeling out from the nose.

Would that sort of behaviour cause a log event in the ACARS or would you have to "Execute" for it to log?

[aviation_watcher]

ACARS at 1:07

If a plausible theory says that the 1:07 ACARS is that of the 12 minutes window to change a waypoint to do the westward turn. I wonder if it is likely the other subsequent waypoints of the new path that are keyed in would appear in the ACARS message? Afterall ACARS contains enough capability of interfacing with the FMC on flight path changes - in uplink and downlink modes.

[The Wawa Zone]

Do we actually know, other than third hand unsourced rumours from Reuters or the WSJ :

1. if the thing actually flew through the waypoints then turned to the new tracks, or just flew near them ?

2. when Vietnamese or Malaysian air traffic actually declared a SAR phase and messaged this to neighbouring country's air traffic services organisations ?

3. if Burmese or Bangladesh radar ever painted anything ?

4. if 'goodnight' etc was all that was said (bad) or was just tacked on to the end of a normal frequency change acknowledgement (good) ?

5. where the story about the new wpt in the FMS came from ?

Until we know these for sure, all that we know is that the aircraft is ... missing.

[Vinnie Boombatz]

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.

[rigbyrigz]

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.

[truckflyer]

"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.

[Blake777]

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.

[HappyJack260]

… the Maldives are across the red track from starting point. It would have to have doubled back.

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?

[AndyJS]

@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.

[rigbyrigz]

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???

[merlin_driver]

Originally Posted by SLFplatine

-After 10 days of SAR no wreckage has been found
-Thus the second possibility is most likely

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.

[White and Fluffy]

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

[Lonewolf_50]

Originally Posted by Wolfdog

Did the 777 get a little too close to an American carrier group?

Nope.

That would get it done.

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. )

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

[galaxy flyer]

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