Pilot needs this to be highly accurate (9)
I believe the answer is:
altimeter
This clue might be a double definition.
'pilot' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'this to be highly accurate' is the second definition.
The definition suggests a singular noun which matches the answer.
'needs' acts as a link.
(Other definitions for altimeter that I've seen before include "It measures height above sea level" , "Height sensor" , "equipment for pilot" , "Aircraft instrument" , "Pilot's gauge" .)