We have found that the biggest challenge to SOPs is when experienced pilots from other airlines (due to furloughs or shutdowns) are hired.
It has proven to be much more difficult and time consuming to
untrain these pilots from their previously trained ways of doing things than it is to train pilots without previous airline exposure.
For some folks change is more problematic than for others. Needless to say, some well qualified, type rated, experienced pilots were unable to successfully complete line training.
Sad but true.
