Very important to make it very clear that the report refers to Warnings, not cautions.
I always felt, that those terms were used in a rather unprecise way. I might be wrong, but wheter that CDS screen was operable or not appears to me not so much relevant. The referred to warning lights are old style, real, "mechanical" lights at the top of the instrument cowling, they should live independent of the CDS' health.
Thus, even if the CDS were dead, the "recorded" ((c)AAIB) sequence of red warning light illuminations is a separate piece of user interface.
That is why I recently asked the forum if anyone could testify as to what kind of "recording" of events was going on for each warning light:
- real supverision of lights illuminating (very expensive circuitry)
- supervision of electric current to light in normal range
- just the fact that the ciruitry did output suitable voltage, w/o checking it there was a current drawn by a light, too.
1 requires a photodiode per light to check illumination
2 is what nowadays cars are doing, logging anything out of the ordinary on the electric driver side of the light (short to GND, short to V+, unplausible current, open)
3 would log events
w/o being proof, that the light would actually have consumes electricity and lit up!
Example:
If there were some common warning light power line for all warning lights (bad design, IMO) and that power line would - for whatever reason - not have been powered (blown fuse), monitoring method 1 and 2 would notice the lack of illumination, whereas method 3 would be
ignorant of that lamp failure.
So what informantion does that "recorded sequence of warning lights" actually contain, in case of an EC135?