Posts by user "DaveReidUK" [Posts: 55 Total up-votes: 202 Pages: 3]

The Indian AAIB successfully downloaded both FDR and CVR data from an Air India 787's EAFR relating to an incident in 2018, so your misgivings on that account are unfounded.

Absolutely.

If the aft EAFR ceased recording at the point (just short of the runway end) where the ADS-B and likely everything else went dark, then the extra 30 seconds of CVR recording from the forward recorder could well be crucial to the investigation.

That's an interesting possibility. The independent power supply for the forward recorder also powers the cockpit area microphone, but not the individual crew mikes, so working out who said what could well be dependent on being able to recognise the voices.

No, only the forward EAFR is connected to an independent power supply, and of course it will then only collect data from sources that themselves remain powered on.

More or less.

There was a discussion of engine remote monitoring in the previous thread.

IIRC, "real-time" means downloading batches of data every 30 minutes or so - which of course is fine for EHM, not so good for accident investigation.

The figures being bandied around for the speed profile during the airborne segment of the TOD look a bit odd.

Firstly, because there isn't actually any speed data in the FlightRadar24 download (and even if there were, the aircraft doesn't send Airborne Velocity packets at the same time as Airborne Position ones). This is a longstanding issue with FR24, and it means that any graphic showing speed at a given position isn't necessarily 100% accurate:



Secondly, and assuming that FR24 has calculated GS as a second-order parameter, rather than a transmitted value, the instantaneous values still don't quite match the data in the download.

It's easy to see that by correlating how far the aircraft has progressed against the data timestamps. Charting the remaining distance to the end of the runway against an arbitrary timescale starting from the first of the 8 data points looks like this:



Obviously the slope/gradient of the blue line represents the average GS between successive points. The yellow reference line corresponds to a GS of 180 kts (ignore the offset, just use the slope for comparison).

Yes, the aircraft had clearly slowed down after rotation, but the final two data points appear to show that it had stopped decelerating by the time the transponder stopped sending.

One wonders how FR24 arrived at its groundspeed values?

FR24 has, at the last count, 3 fundamental issues with the way it reports and displays data.

All are readily worked around, after which what's left is the same data that underpins many of today's ATC systems.

If only there were an easy way of telling how much fuel had been loaded for the sector ...

At least one previous investigation report by the Indian AAIB has used CVR and FDR data downloaded from an (intact) EAFR.

You may be thinking of a Quick Access Recorder (QAR), which is indeed designed to be downloaded in situ. They've been around for a while.

That aside, I think we're agreed that downloading an intact FDR/EAFR is probably several orders of magnitude easier than one that's been burnt, battered or bruised.

Yes, the AIC 787 had the GE EAFR..

I believe the GE EAFR continues to function as both FDR and CVR for a minimum of 10 minutes following a power failure.

However you are correct in that the requirements only specify that the CVR functions and the CAM must continue to operate.

The engine removed in March won't have been re-installed on the same aircraft.

An "expert" who can't get something as basic as a runway slope calculation anything close to correct doesn't inspire much confidence in his other "analysis".