You'd go crazy trying to track and analyse **in advance** every sizeable short sale. Look it up in WSJ, 3rd Monday (I think) of each month, full tables of short interest on NYSE, NASDAQ, AMEX. Then compare this month's table to last month's -- no freaking way. This would have to be a **reactive** tool; after a terrorist attack, look up who's short, and how much and how long they've been short...and if the bombing shoe fits, confiscate the profits. Been done many times...the late Lawrence Sanders even wrote a short story about it once.
Short volume in airline shares has spiked on many occasions prior to 9/11, one famous example being August-October 1990, after Saddam's little excursion into Kuwait. There's nothing particularly indicative about an expansion of short volume...**before** the fact, sorry.