Originally Posted by PJ2
Instead, the PF launches into something on his own, leaving the PNF out of the loop, bewildered and trying to catch up while guessing what was happening.
It has been apparent to me for quite a while that AF447 encountered a roll PIO after the the autopilot dropped out. What I have been surprised at is the lack of understanding by other pilots, particularly some very experienced ones, of just what this means to the pilot who is attempting to fly during a PIO. In fact, from the low key recognition by BEA of what the roll oscillation implied, I suspect that they did not appreciate the impact of a PIO on the pilot flying.
As I have said in the past, I did briefly experience a divergent roll PIO in an early visual simulator, and I do understand the potential impact on the pilot flying and it is devastating in a number of ways. Apparently this experience makes me part of a very small group who had an encounter, so I feel obligated to try to pass on an understanding to others.
Supposing you were hand flying and your aircraft suddenly began to roll continuously in one direction. Would you be able to handle that using CRM?
The best you would probably do is have both pilots applying counter roll yoke/stick inputs. It would de-structure a crew in short order if you did not get it under control.
Having your aircraft roll in an oscillating manner contrary to your control inputs is equally distressing. I have described my experience as like beginning to fall and desperately looking for a hand hold. Does that sound like another day at the office?
PIO only occurs when a pilot is executing direct manual control. Since most of you are flying almost the entire flight on autopilot, you will have fewer potential encounters with PIO than was previously the case in my day.
There have been some PIO incidents with modern aircraft. Some that come to mind are a few roll PIOs on approach in the A320 series and AA587 with the yaw PIO, and of course AF447. They are infrequent and difficult to predict. They are very dependent on pilot control strategy. You can just about bet that Bonin routinely employed the mayonnaise stirring technique when he flew.
PIO incidents greatly increase the probability of accidents. There are a few things that can be done during training to decrease the likelihood of encountering PIO while hand flying.
- Expose pilots to PIO events in simulators. Once in a lifetime should be sufficient.
- Monitor pilots' control techniques during training and promote a minimalist style of flying. Just because the FBW system lets you get away with mayonnaise stirring does not mean that it will not bite you some day as it did with AF447.