The recommendation from MDC (now Boeing) is that if the ATS is available, it SHOULD be used. This is different from the BAC philosophy - if AP is disconnected, ATS should also be disconnected.
Our company follows the MDC recommendation, so ATS generally always engaged.
Way back when... my IOE instructor was a MDC test pilot with the MD11 program and he also stated that if MDC had their way, the MD11 would have be installed with only start switches and no throttle levers per sic.
