PPRuNe Forums - View Single Post - AF 447 Thread No. 6
View Single Post
Old 30th Sep 2011, 17:46
  #1022 (permalink)  
RR_NDB
 
Join Date: Feb 2011
Location: Nearby SBBR and SDAM
Posts: 875
Likes: 0
Received 0 Likes on 0 Posts
Finite-state machine in FBW a/c

Hi,

FBW is clearly a way to optimize an a/c. (weight reduction, easier to design with redundancy, etc.)

Question for EE and pilots acquainted with Digital FBW a/c:

The problems arise when the machine (a/c) enter some certain states?

E.g.: TAM 3054 overshoot, AF447 first with THS "going" to 13 degrees NU and later presenting erratic SW indications. These planes entered exceptional "states"?

May we consider these planes "entered" strange states difficult to be understood (almost impossible in short time) by crews yet submitted to abnormal and stressful situations?

In non DFBW these "strange states" are rare. The NW 6231 727 (Thiells) Pitot's "memorized pressure due icing" misleading the entire crew. Perhaps we can say the plane entered an "strange state" with it's Pitot's "showing" altitude (instead the speed) to the (astonished) crew.

In summary, my 1st question is:

State machines concept may explain several cases where the crew was not able to even understand what was going on?

Observe the issue is not FBW (a good approach) but how we "protect" the plane using "finite States machines". And Airbus SAS pioneered this.

A possible 2nd question is:

Is it possible, by training, prepare the crew to timely understand (the strange states) and act accordingly?

Are we capable to preview the "strange states" the complex machines (full of protections) may enter?

Last edited by RR_NDB; 30th Sep 2011 at 18:44. Reason: Text impvmt.
RR_NDB is offline