Even though it seems that the ACARS had been disabled the FMC GPS's would probably have still been receiving signals from EGNOS or the MSAS satellite system, are these signals traceable ?

All you need is a Li-io based fire to burn the cables to the transponder and VHF3 antenna. Both go dead. And you certainly get some nice hotspot that potentially could burn a small hole into the fuselage.

irony or symbolism
 

Is it ironic/symbolic that, 370 pages into this mystery, many posters here remain in complete & utter denial that the evidence available practically demands human intervention be the most likely cause???


Time will hopefully tell...

GPS receivers don't transmit!
 

Sadly, popular media showing people being tracked by the GPS receivers has confused too many people. GNSS (GPS/GLONASS/...) receivers do not transmit anything. They only receive. They receive signals from several satellites, and using the timing from them, calculate their position. EGNOS and MSAS likewise only receive correction data *from* auxiliary geo-synchronous satellites to make the primary GNSS signals more accurate.

Caveat: almost all radio receivers emit low level signals (leaked local oscillator, digital system clock noise, etc). This is irrelevant to their being trackable except from very close (a few tens of meters).

:ugh:

Above The Clouds Even though it seems that the ACARS had been disabled the FMC GPS's would probably still been sending and receiving signals to EGNOS or the MSAS satellite system, are these signals traceable ?

To my understanding SBAS is a one way augmentation system, the GEOs just transmit the GPS corrections and they do not receive anything from the aircraft. Therefore MSAS or GAGAN, the two SBAS systems possibly covering the flight profile would not have 'seen' the aircraft. Furthermore, to my understanding very few 'high end' aircraft are fitted with SBAS receivers.

GNSS receiver - no, you rally can't track it
 

Yes, which has nothing to do with tracking a receiver.

:ugh::ugh:

Are the Primary Radar Returns a Red Herring?
 

Until the public sees data that unequivocally shows a strong tie between the last SSR response and the Westbound primary track to the North of Aceh, we need to accommodate the possibility that MH370 took another track that ended up somewhere within an hour's flight time from the last ping arc.

That Westbound track is highly redolent of diversion. Perhaps the NTSB and/or AMSA are privy to data not shared with the public that supports this track.

Mesoman

Stop banging your head on the wall.

I am asking because our aircraft are fitted with SBAS and depending on where RIMs station are located and if signals from geostationary satellites are being received, the transmission of some SBAS signals currently come from INMARSAT satellites, hence my question are they traceable I.E by INMARSAT.

Crucifying the crew is par for the course in most cases. Nothing unusual there. And if no cause is found... guess who is to blame by default?

As for the sensor software question, I believe all critical systems (including FBW/FADEC) on the a/c were developed by isolated separate design teams in triplicate using the Ada-83 standard (and later rewritten in Ada-95) and use an n-version (n=3) voting system for agreement/disagreement.

I don't think any *Boeing* crash has ever been attributed to software issues (MMI issues are something else), and the architecture has been pretty well proven and refined over the years not unlike all other engineering processes.

Pings and tracks etc..
 

The graphic in post #5965 has further been updated with the positions of the LKP at IGARI and a possible PSR position at 1822z, that are interlinked to the possible backtrack position west of Banda Aceh.

But those cables do not route near the fire. There are transponder and VHF antennas in the roof of the aircraft.

Everyone seems to be assuming a magic fire that can take out all the alternate communications - avoid the SATCOM and anything that prevents the aircraft flying normally - but depressurize the aircraft - and all before the hold fire warning and before the pilots notice and squawk or transmit Mayday.

If both pilots became disabled, and unable to respond to calls from the cabin crew, would the cabin crew have any means to open the inviolate cockpit door?

Reason I ask is perhaps one pilot disabled the other to carry out some plot, but before that pilot either died or became unconscious, he retaliated in some fashion to disable the other pilot.

Now in this scenario, we have two disabled or dead pilots behind a locked cockpit door, the plane on autopilot until it flames out 8 hours later.

There seems to be an assumption that the aircraft couldn't remain airborne for hours without either a working autopilot or human input. This assumption is almost certainly wrong.

Water impact
 

Have the boys in the 777 simulator shut down both engines and seen what the aircraft does until impact?
Airspeed, rate of descent, systems failures, autopilot disconnects ect.
You would have to do a number of scenarios, both engines shut down at the same time and one engine fails then the other, various autopilot setups IAS, Alt, Heading, Nav ect.

Flying for eight hours without either the autopilot or human input would require an inherent stability which just doesn't exist!

Hey mm43 thanks for the updated graphic, though as I mentioned before the projection is wrong. You need to either correctly project the satellite ping radius on the map projection you have (it won't be a circle anymore) or use an azimuthal projection centred on the satellite (then you can use a circle for the ping distance). The equidistant projection you are using is only equidistant with respect to latitude (vertical) distance from the equator and not equidistant at any angle from a point (even if the point is at the equator).

Yes, there is a procedure that allows cabin crew to enter if both pilots are disabled. One possible scenario is that in addition to the pilots, the cabin crew and passengers were also disabled.

EDIT:

To "Heli-phile" (who was concerned about my post but won't take PM's)

This information is just common sense. There would have to be a way for the cabin crew to access the flight deck in case of an emergency. And there would also have to be a way for the pilots to keep people out if needed. This basic information is already available online for anyone who cares to look for it.

This procedure varies with each airline and of course I would never describe the exact procedure at my airline.


SKYbrary - Flight Deck Security

Yes but only if both pilots are incapacitated. Pilots can reject any attempt to open the cockpit door through procedural means from outside.

IOW The cabin crew can try all day to open the door from the outside, but a conscious pilot in the flightdeck can prevent this each and every time.

Robert,
The 777 is FBW. It does not require trimming for power changes, only for speed changes. Once its trimmed, and autothrottles are looking after the speed its very stable, and flies very nicely hands free.
There are plenty of incidents where aircraft have continued on autopilot after the crew have become incapacitated.
If in the cruise and the fuel starvation point is reached, one engine could fail before the other. In this case, autothrust (autothrottle? been a while since I was on the Boeing) would command the live engine towards climb thrust (max cruise setting), and the autopilot would look after the rudder to keep things straight and try and maintain level. As the speed decays, slow speed protection will then cause the aircraft to descend. When the other engine fails, the engines may be rotating fast enough to keep the generators online (if the Tas is high enough), if not the RAT will deploy to keep electrics. Hydraulic pumps too will keep working as long as the engines rotate fast enough. Either way the autopilot and flight controls will remain active until ground impact.
I don't think it will be the dramatic departure from controlled flight that has been explained here previously.

If you would rather read something factual...

Search Press Release

AMSA Website