A good instrument scan is a fast disappearing skill, predominantly due to the use of automation (FD /Autopilot). The sole use of automation is not a hazard provided the SOPs, (normal and abnormal), and the aircraft systems (normal and failure cases) support this form of operation. In many cases the systems failure case is not supported and training is required to compensate; this can be done during routine operations and thus raw data flying should be encouraged. However some operators (and regulators) who overlook this point and are either oblivious to the increased risk or accept it for the rare occasions.
A greater concern is the loss of scanning skills. This is reflected by loss of situation awareness for both automatic systems and for other aspects of flight operations. “Dependency on automatics leads crews to accept what the aircraft is doing without proper monitoring” – chapter 4 of
CAA PAPER 2004/10 Flight Crew Reliance on Automation.
I believe that there are many problems which stem from poor instrument scanning. In the first instance how does an operator ensure that the habit (good or bad) from basic training on a ‘steam’ aircraft are transferred / negated during transition to a glass cockpit. Similarly when changing types.
Then what training is provided for use of alternative scan patterns for different flight situations; climb, cruise, and approach, these would not necessarily require the same scan pattern, and there are significant differences between precision approaches and NPAs.
Finally I have concern that the loss of scanning skills is reflected in the current weakness of gaining and maintaining situation awareness; do pilots know what is important, what to look for, where it can be seen, and when they should be looking for it; all of these skills can be developed and improved during raw data flying.
Operators / captains should remember that raw data flight need not be as accurate as automatic flight; it only has to be sufficient for safety. This understanding should remove unnecessary pressure both from the PF and the captain, but in turn this requires knowledge of what is sufficient for safety – see rules and procedures.
Cautionary note; some aircraft designs do not easily enable ‘split’ auto/ manual operations, thus it would be advisable that both pilots use the same display format during raw data operations. Not only would it keep them out of trouble (at least one serious loss of control incident in Europe due to split FD/raw data flight), but it would also enable the monitoring pilot to improve his skill of using raw data as the monitoring source – something that should be considered as normal.