Perhaps something like this:
=query(A:C;"select C where A=x and B=y")
y replaced by what it is you wish to select.
Since sight of your spreadsheet, I am not sure of what you would like where but suggest:
insert a column immediately to the right of D in Fleet Log and in E2 enter:
=C2&"|"&D2 and copy down to suit.
in Sheet5 Cell C3:
and copy down to suit.
I suspect =VLOOKUP will not work 'backwards' (ie to its left) but INDEX/MATCH may suit. Keep the formula from 1. above but put it in G2 instead (without inserting a column). Then in Sheet5 Cell C3 copied down to suit:
=iferror(Index('Fleet Log'!$E:$E,match(C$2&"|"&$B3,'Fleet Log'!$G:$G,0),""))
I'm getting curious to know whether this will work/suit!