Originally Posted by
RichardC10
I was trying to use the simplest possible model that will satisfy the data to the level of error in that data, which I estimate to be ~2Hz, one sigma. So I have used two parameters only, the speed of the first leg and the speed of the rest of the legs. As noted in section 7.9, the speeds of the first and second legs can be traded to move the position of the 18:29UT ping North, without affecting the fit. We are on very dodgy statistical ground here. There are only 4 reliable BFO data points at most, and I am fitting two parameters already. If I fit more parameters there is a danger of 'over-fitting', which means any data can be fitted. What the fitting process must avoid (of course the investigation knows this) is to avoid just joining the data dots with a complex model. Such a solution would definitely not be correct, there is noise in the data and this has to addressed.
I completely understand that you are seeking for the simplest model integrating what we factually know to describe the observed data.
I have still to rerun my MC simulation (BTW Gysbreght, the most probable/most fit offspring trajectory is not the mother/reference trajectory and in fact, the output probability density function is not even centered on the mother trajectory) with the new BTO/BFO data extracted from the log files to see to which extend is it possible to avoid the Indonesian airspace (see below) and be compatible with the supposed Butterworth radar track.
I also tend to agree with you when you say that a trajectory mimicking the radar track over the Malacca strait should not be imposed as a constraint but should be a resulting feature of the produced trajectories, but we do not have observed BTO/BFO data between ~17:10 and ~18:30... would it be a good sign if the reference trajectory is set along the radar track and if the resulting most probable MC trajectories do not shift this a priori leg over the Malacca strait along the radar track ? (not sure I am very clear...).
Originally Posted by
RichardC10
I have been concerned that presentations (to the families) have made attempts to bend the path round Indonesia. The ping rings in the slides shown were not those derived from the data log (or from the slide of satellite elevations). The precisely defined 18:29UT turning point in the slides seems to be an assumption about the navigation process of the flight - perhaps correct, but not supported by any fact of which I am aware.
I am curious about the 1st legs (till 18:29) hypothetized by the independant MH370 study group (see Duncan Steel website) since their 470 kts south trajectory seems to avoid the Indonesian airspace and I assume that their trajectory is compatible with the BTO/BFO logged data.
Originally Posted by
RichardC10
Yes, I think a course can be generated that will satisfy some of the data around ~18:29UT, but I am not sure it adds any weight to the fit, that is a degree of freedom has to be used up matching the added data point.
On the time data series I will work on that. It will require an assumption about how the course changes between ping-rings (as a function of time) - at the moment I have just modelled one course per leg. That can be done of course, but it is another assumption.
Here is the kind of underlying continuous time serie I get for D1 + D1_AES (compensated D1):
https://drive.google.com/file/d/0B3s...it?usp=sharing
it seems to suggest that the 3 handshakes around 18:28 occurred at a time (~120 min of flight time) when this term D1 + D1_AES was highly variable (during the south turn)... In my MC simulation this instant of 18:28 also corresponds to the maximum doppler variability of the enveloppe (of the simulated flights): some flights with ad hoc relative timing between the turn and the handshakes are able to reproduce the 3rd handshake (it would not be a question of trajectory but of relative timings between the handshakes and the turn sequence); Inmarsat's north and south predicted BFO also tend to reproduce this 3rd handshake: isn't it meaningful if it is where the divergence between north and south BFO profiles occurs ?
Can we now say that Inmarsat early doppler analysis (which concluded that the A/C went south) was completely correct ?
Do anyone know about a trusted fuel consumption model for the 777-200ER ?