BOAC;
RECAP!! Do we ACTUALLY have any 'ACARS message' about waste water other than a possible vaccuum flush fault?
No, we do not.
The early, Class 3 maintenance message "LAV" would have nothing to do with any water/overflow issues. The "waste-water" theory is emerging in the absence of evidence. It is almost certainly a non-starter.
I did ask 'the experts' a day or so ago which choice - continuing ahead or turning back through the weather - would be likely vis a vis ETOPS/fuel etc. and have had nothing back.
Originally Posted by is this the post you're referring to, BOAC?
. . . if only we could be sure we have ALL the ACARS messages in sight, then there is a very good chance we can rule out a high-level break-up in view of the lack of an "EXCESS CABIN ALT" warning as you say. Without such a signalled disruption to the cabin pressure, the only subsequent ACARS message must surely refer to a descent? Dare we surmise? PJ? Bsieker?
If that's the post, I do have a few comments:
Your post doesn't ask about a turn-back, it only suggests the possibility of a descent as may be indicated by other, associated messages (which, as you say, may or may not exist).
First, a bit of background on the ACARS ADVISORY message:
When a system requires the crews' attention but isn't serious enough to warrant formal master caution/master warning indications plus other associated ECAM actions, the affected system's page is brought up on the lower ECAM, displaying a pulsing green 'advisory' message of the relevant parameter, in this case, the "CAB PRESS" text display on the pressurization page.
An advisory message to the crew does not necessarily require immediate crew action but advises that system parameters have been exceeded, not by a lot but crew attention/advice is required.
The ACARS cabin "ADVISORY" message refers to a pulsing, advisory 'CAB PRESS' message displayed on the pressurization system page on the lower ECAM display.
From the QRH, the "CAB PRESS" pulsing green ADVISORY message is displayed when:
- the cabin vertical speed is greater than, or less than, 1800fpm, or
- the cabin altitude is equal to/greater than 8800ft, or
- the cabin differential pressure (delta 'p') is equal to/greater than 1.5psi in flight phase 7.
Flight phase 7 refers to the approach phase below 800ft AGL to touchdown.
In each case of an advisory message there are recommended crew actions listed in the QRH. These action items are, as described, not of an emergency nature.
That doesn't mean that there was no emergency - it just means we don't have further ACARS messages.
This in and of itself wouldn't indicate either an aircraft descent or a turn-back. There would not likely be any ACARS messages associated with a descent per se, (and certainly none automatically associated with a turn-back), although a "top of descent" message may be automatically sent as a matter of individual airline ACARS design requirements - we don't know.
I understand the theory behind takata's fine sleuthing work and hope it bears fruit but as we can see, there are other considerations emerging which may place the aircraft differently. Very frustrating for all, as we know.
It is impossible to say whether the crew turned back and it is equally impossible to say whether such a decision would have been made or by who, (depending upon who was on the flight deck - we may surmise it would "definitely" be the captain, but we do not know this).
A turn-back at that point in the flight is a highly unusual response - it is essentially an emergency response made out of dire need. I can see a 90deg turn to the east to avoid Cu but that is not the maneuver contemplated by takata's work.
Clearly, there is a pattern, though "the data" is granular in nature, to where the wreckage and most bodies were found. I think takata's work is on the right track and (as I believe s/he him/herself would say), may require fine-tuning. I wouldn't be prepared to say there was a turn-back but such a notion teased as it is out of what little is known, is now a factor which must be proven/discounted.