How does that impact the investigation? Just curious. i.e. whether circuit breakers were deliberately triggered or automatically triggered due to an another technical incident for some reason. The end effect in terms of aircraft performance resulting from the disabled function is surely going to be the same, notwithstanding the effect on the aircraft of other factors that might have triggered them.

I'd say quite significantly. Can someone confirm that the FDR CB is indeed in the EE bay and that the FDR cannot be disabled from the cockpit by pulling other CB-s higher up the power grid ?

My assumption was that whoever initiated the departure from the original flight plan (and there IS consensus this must have been intentional, though most likely the last hours of the flight were purely on autopilot) with an objective to hide all traces would start by pulling the FDR CB, followed by all comms systems. If this is not possible, the FDR might indeed hold some clues on at least the initial sequence of events.

Are there solutions for constant heading? i.e. rhumb line navigation?

I believe this has been done where the physical controls were disabled but the autopilot worked.

I have no idea of the relevance to 777.

@Shadoko : I agree that the line in Table 6 must be an error.

Regarding the sensitivity to errors in the BFO I feel that between all the computer simulations one tends to forget the basic facts.

Basically the only independent information in the BFO is the line of sight (LOS) speed of the satellite towards the aircraft. It is what richardC10 calls D2_satellite in his paper.

At a given velocity of the sat, D2_satellite is only a function of the angle between sat velocity vector and the line of sight. I.e. all points of equal D2_satellite are located on a cone around the sat's velocity vector. The intersection of this cone with the surface of the earth gives a line of position.

http://www.argos-system.org/images/s.../tracking2.jpg

This principle is used for satellite based location of emergency buoys (e.g.: FAQ - Argos) only that those systems are designed for that purpose and have a much more favorable geometry as opposed to the BFOs measured by inmarsat.

Basically this Doppler derived line of position contains the BFO information which is uncorrelated to the BTO information. The intersection of the BTO line of position (ping arc) with the BFO line of position (doppler cone) defines the position of the aircraft.

On the last ping arc, D2_satellite is greatest due south of the sub-satellite point and it is null on the equator abeam of the satellite. In the middle region between these two extreme ends the variation in D2_satellite can be approximated as linear. According to my calculations at 0:11 UTC D2_satellite is ~12m/s due south of the satellite.

The radius r (not on the surface of earth) of the 0:11 ping arc is ~4000 km
=> the quarter circle section between due south and equator has a length of (pi * r)/2 ~= 6000 km

In the region where MH370 is suspected the variation in D2_satellite can be approximated as linear, then 1 m/s in D2_satellite variation corresponds to
6000 km / (12 m/s) = 500 km per 1 m/s D2_satellite variation.

At 1.6 GHz (L-Band uplink) 1 m/s relative LOS-velocity is equivalent to ~5.3 Hz Doppler shift.

Thus the 1000 km position error for 10 Hz bias error make perfect sense. Actually the error should be much smaller and if it is measurement noise and not fixed bias error, those errors partially cancel out over the series of BFO measurements.

I do not use an a priori AES fixed frequency bias (nor 150 Hz, nor a uniform distribution between 150-5 and 150+5 Hz like in the report), in my simulation the AES frequency bias is estimated (along with another parameter via a linear regression) for each simulated flight so that its simulated BFO profile is the closest possible (rms) to the measured BFO profile. The AES fixed bias obtained through this procedure are indeed close to 150 Hz and I get the following probability density function (an histogram actually):
https://drive.google.com/file/d/0B3s...it?usp=sharing
It is not the uniform distribution between 245 and 155 Hz used in the report, 80 % of the estimated freq. biases are between 150 and 155 Hz.

For this simulation, the reference trajectories are rhumb lines connecting points (constructed under varied constant speed hypothesis) on the varied handshakes:
https://drive.google.com/file/d/0B3s...it?usp=sharing
For each of the reference (non mutated/randomized) trajectories corresponding to each of the ground speed hypothesis (between 320 and 520 kts), the handshakes sample each time the new course taken arriving at a new ping ring. But in its subsequent mutations or crossovers, the relative timing between the trajectory and the hanshakes is also randomized (a handshake can occur slighty before or after the real one/related event on the trajectory).

The best fit is reached between 400 and 410 kts of ground speed, the goodness of fit I use is not a rms (linked to the 2-norm) but the max gap over the flight (linked to the infinite norm), for the best fit, it is less than 5 Hz for the BFO and less than 0.1° for the angle of elev/BTO.

There are rhumb line trajectories intersecting all the ping rings, with variable speeds, they depend where your starting point (at 18:29) is:

best bearing (so as to minimize speed variations) as a function of the starting point (lat/long)
https://drive.google.com/file/d/0B3s...it?usp=sharing
the blue circle portion is the 18:29 ping ring

associated (for the best bearing) mean speed as a function of the starting point (lat/long)
https://drive.google.com/file/d/0B3s...it?usp=sharing

associated variability (std) of the speed as a function of the starting point (lat/long)
https://drive.google.com/file/d/0B3s...it?usp=sharing
the best rhumb line trajectories exhibit a 27 kts standard deviation (speed variations) from their mean speed.

Sorry to disrupt the BFO things, but why the 00:11 handshake has been at this time and not at 00:15?

A phone call at 18:41 (channel released at 18:40:56.354) seems to have zeroed the one hour timer at 18:41, so the handshakes at 19:41, 20:41; 21:41 and 22:41. All of them in a ± 30 seconds interval. The next would have been at 23:41, but there was another phone call at 23:13:58.407 with the channel release at 23:15:01.886. This might have reset the one hour timer and without any contact, we would expect the next handshake at 00:15. And later, it was at 01:15:56 (so a two hours + 56 sec from the time of the phone channel release) that a not answered handshake from the sat happened, because the "partial handshake" of 00:19 would have not reset the timer.
But why a 4 minutes early HS at 0:11? From the Inmarsat data, it has been clearly initiated by the sat.

Just a remark. At 00:19, the whole larger search zone (the grey zone, page 42, 47 of the PDF) was in daylight, with the sun just rising near 40S 85E, and about 20° above horizon near 17S 107E (at sea level).

You guys having this discussion are obviously a whole lot smarter than me, as I was just a corporate pilot and now in "management". Would it make sense to take a 777 run it out where they think it went and see if these "pings", data points, signals and see if they match via all of these magical formulas? Just my thought.

Thanks. The reason for asking about the rhumb line is that I'm looking for any assumption which might narrow down the possible heading. It occurred to me that the South Magnetic Pole might be a testable hypothesis if it could result in plausible tracks.

Probably not. First, the route it ran would not be the actual route of MH370. Second, for calibrating the BFO (which is the more problematic measurement) one would want to carry the actual SATCOM equipment onboard MH370 and be able to return 3-F1 to its original, eclipsing orbit and inclination. Neither is going to happen. The formulae have been tested on myriad other aircraft, so the basic equations are not in doubt.

On the FDR breaker(s) If someone has a CLG for a T7 they could shed some light to locations, but on a NG3 there are 4 breakers for the FDR not 1. Takes power from both AC and both DC buss. Don't want the FDR to stop if there is any power left...

Highly doubtful all 4 would pop at once.

This would be very dangerous because this aircraft will also fall in fuel shortage as MH370 (for the sake of configuration respect) .. unless it is equipped with a system of refueling in flight (it remains to construct) :)

This claims to be the cockpit switch and breaker layout.

click on maintenance and the four panels shown can be selected and enlarged so you can read the breaker/switch functions. The enlarged views are not interative.

Going back to top of page and select the other cockpit areas Overhead, Glareshield and pedestal , these are interactive.

777 Flight Deck Maintenance Panel

Would pulling AIMS disable input to FDR and would you have to pull all of them?

Not much good for searching underwater. There are far more important national security priorities that these assets get assigned to. That is what those UAV's were built and paid for.

- I think the really clever people will find a way around that?

I have tested this for great circles between waypoints (LNAV mode), between BEBIM (and a shifted version to the east) toward 3 destinations: the south pole, the Wilkins airport and NOBEY
...to compare to the final portion (between the 2 last ping rings) of the varied south legs (corresponding to varied ground speeds from 320 to 520 kts)
https://drive.google.com/file/d/0B3s...it?usp=sharing

The -300ER triple has no CB's on the overhead to remove power from the FDR. It receives all information from AIMS L/R. I am not aware of any alternate inputs to the FDR. Having both AIMS fail is very unlikely though the AIMS CB's are on the overhead.

MH370: New evidence of cockpit tampering as investigation into missing plane continues - Telegraph I thought this would have been discussed on here yesterday. Or perhaps the posts were deleted...

That green rhumb line which just touches the top of the high probability area coincides exactly with a rough plot I made on Google Earth using some information about the ping arc diameters and a set of assumptions about how I think the track looks at the northern end.

Thank you for posting that.