Blocking a tail number from the online flight tracking programs could become more difficult, if not impossible for some. The Department of Transportation is reviewing the NBAA's Block Aircraft Registration Request (BARR) policy this month, and hints that criteria for participating in the program could become far more restrictive. As it is now, anyone wishing to block their tail number from the data presented on flight tracking programs such as flightaware.com can apply to the NBAA to do so. In future, aircraft operators may be required to demonstrate "bona fide security concerns," according to NBAA President Dan Bolen. NBAA is currently polling its members for their input on the proposal, which would affect current users of the BARR as well as those who might make use of the privacy feature in the future.