Are we missing something here?
I am keen to understand more about the significance of the “Advisory Cabin Vertical Speed” transmitted at 0214.
Until a few seconds before this message all ACARS related to the suspected loss of reliable pitot information and sequenced deactivation of systems depending on it. Namely A/P , A/T airspeed displays and degraded control law etc.
There has been much discussion on the techniques of handling a loss of reliable airspeed. Power plus attitude maintained at cruise values would generally be expected to suffice and should not readily see the aircraft depart controlled flight. So do we assume that the aircraft should have been right side up and under some degree of control to this point?
But what of the “Advisory Cabin Vertical Speed” which the report states;
Symptoms: Flashing of the cabin vertical speed indicator on the SD’s PRESS page.
Meaning: This message indicates a cabin altitude variation greater, as an absolute value, than 1,800 ft/min for five seconds.
This is cabin rate, not aircraft rate. If the hull was still intact it suggest the Cabin Pressure Controller (lacking good altitude input) had perhaps lost control over pressurization. Did the crew, already facing a dire situation, become aware of a rapidly climbing cabin altitude and initiate an emergency descent?
Turn off track! Lower the nose, Thrust Idle and Speed brakes out!
That severely challenges the “maintain power and attitude for cruise” scenario.
With speed brake the already limited speed range between high mach stall and low speed stall is dramatically reduced. Without displayed IAS and considering the associated buffet and likely turbulence it would have been a difficult task for any pilot in their predicament to stay within normal flight parameters!
So was the “Advisory Cabin Vertical Speed” merely a further symptom of things going wrong or a contributing factor? Perhaps the straw that broke the camel’s back.