gums;
I am saddened to see some of the frame rates BEA references,
. . . .
Data acquisition units are damned cheap -
And compact - memory and processing power is cheap.
The expensive parts as you likely know, are the STCs, the cooperation from Boeing and Airbus as the case may be, to obtain dataframe information on older aircraft to be able to verify/update/change DFLs to capture more parameters.
It isnt very often that it is a physical sensor and/or wiring problem, but a lot of this information is proprietary and therefore cannot be legally shared even just to help someone out with a dataframe issue such as conversion factors or knowing where the words are put for a certain parameter. THAT is where the time, money and even political problems lie because the airlines lobby against any legislation which can increase costs without a "direct, demonstrable" benefit.
Refitting DFDAUs/FDIMUs (not even recorders), is an extremely expensive proposition...new DFDAUs in older airplanes can run, all in, over US$60,000 per airframe even though the equipment itself is comparatively inexpensive. Why should we take that route when "88 parameters at the legal sampling rates is legally good enough"? I have heard that a number of times, along with "we'll just take the 'statistical approach' and equip a few airplanes in the fleet." The joke was, at the end of the day we all had the "GE" trademark from the FOQA lab fridge embossed backwards on our foreheads.
Obtaining certification for changes to DFDAU software, which is essentially a licensing matter and not an engineering/certification matter, puts such changes out of reach in terms of making the business case for most airlines. While some know the value of data and support the work wholeheartedly, you wouldn't believe the gyrations some airline managements go through to avoid such "unnecessary" changes. One can't expect a blank cheque, but one can expect the understanding that not all departments can be "profit centers". I'll leave that particular item at that.
... some even tens of $$$ for precision in terms of tenths of a gee, or fractions of a degree of surface movement, or tenths of feet per second at 100 hz for velocities. It's the final "mother" recorder that has to store it all for later analysis. And much data can be acquired and transmitted with tiny messages, like 8 bits to get 256 th's resolution of a parameter.
Precisely.
The International Working Group on Flight Data Recovery, (link on the
BEA AF447 website) submitted their final report on "lessons learned", called "
Triggered Transmission of Flight Data Working group". The need was stated quite succinctly in the working group's first report: "
The difficulties encountered have raised questions about the adequacy of existing flight data recovery technology, when considering accidents over oceanic or remote areas."
I don't want to discuss AA587 nor the larger issues now outlined here by many contributors, but here is another problem highlighted by yet another accident: - locating the recorders in hostile, essentially inaccessible environments.
If the industry wants high data granularity of the very kind you're describing for SMS and accident investigations, it is from the regulator, not private enterprise under a de-regulated economic environment, that the mandates to do so must come.