a. Police — call up the FBI, INTERPOL, etc. to pursue all possible leads and conduct a formal police investigation of the passengers, crew, and cargo aboard the missing jet.
b. Military — call up the commanding officers of the US Navy, NATO, and other military powers to conduct a large-scale military search and rescue mission by land and sea.
c. Science — call up the engineers at Google, Microsoft, etc. to create a probabilistic or Bayesian statistical computer program projecting the airplane’s most likely travel path.
d. Cash Reward — call up the Treasury Secretary or the leaders of the airline industry to offer a hefty reward or bounty (say, $1 million USD), payable to whomever finds the missing airplane first.
(*) By “best” we mean the fastest and cheapest method of solving this puzzle.
Next question: Why hasn’t choice (d) been tried yet?
prior probability 
I think they all make logical sense; and as weird natural and human driven disasters do seem to be logically based, searching is always scientifically sound . However D seems like a pretty good answer- perhaps a trade of something instead of cash. I’m not sure after the Austin powers movie that 1 Million Dollars carries enough weight anymore. And of course, I assume we are pretending that Israeli Massod isn’t already working on it. (Or knows).