From HS Today:

Ever since the US Airline Pilots Association (USAPA) issued a “briefing” to its members earlier this month warning them about possible dry-runs performed on passenger planes by possible terrorists, there’s been considerable debate among pilots and counterterrorism authorities over whether terrorists continue to conduct such probing and surveillance activities. Most of the debate has centered on whether the incident discussed in the USAPA bulletin represents a legitimate concern, and whether terrorists continue to be involved in probing US aviation security measures.