When I put my P70 into airplane mode through Windows 10, it stops accepting power from the AC adapter and runs off of battery. Is this normal? I don't see anything in Windows help or forums to indicate this is normal activity. As soon as I take it out of airplane mode, it starts running off the AC adapter again. I'm running the latest P70 BIOS (2.00)
"Airplane mode" in OS refers to both wireless and power. Airplane mode wireless means "all radios off". Airplane mode power means "use less than 60 watts to avoid tripping airplane circuit breaker". On workstation class system like P50/P70, this has the effect of disabling the AC power because it cannot use less than 60 watts.
You can change a setting to avoid this behavior:
run Lenovo Settings
from the left side panel, click on the battery button to open the "Power" section
scroll down to "Airplane Power Mode" and then uncheck the box about "Enable auto-detection". This means airplane power mode won't be activated automatically when airplane wireless mode is turned on.