For small planes a 20-30 foot range isn’t abnormal for hand flying if you’re paying attention. I’m sure in cruise an airliner is using an autopilot though.
I once had ATC ask if everything was cool on flight following after a hundred foot drop and I was surprised they were paying that much attention. I had forgotten to put my life jacket on before a water transit and while I was putting it on handed it off to my wife who hadn’t taken lessons yet (she later got her license!). It was interesting to see that their tracking was precise enough for them to chime in.
I once had ATC ask if everything was cool on flight following after a hundred foot drop and I was surprised they were paying that much attention. I had forgotten to put my life jacket on before a water transit and while I was putting it on handed it off to my wife who hadn’t taken lessons yet (she later got her license!). It was interesting to see that their tracking was precise enough for them to chime in.