The Transportation Security Administration will let people carry small pocketknives onto passenger planes for the first time since 9-11, along with golf clubs, hockey sticks and plastic Wiffle Ball-style bats.The agency will permit knives with retractable blades shorter than 6 centimeters (2.36 inches) and narrower than 1/2 inch, Administrator John Pistole said at an aviation security conference in Brooklyn. The change, to conform with international rules, will take effect April 25.Passengers will also be allowed to board flights with some other items that are currently prohibited, including sticks used to play lacrosse, billiards and hockey, ski poles and as many as two golf clubs, Pistole said.The changes attracted criticism from labor unions representing flight attendants."This policy was designed to make the lives of TSA staff easier, but not make flights safer," said Stacy Martin, president of the Transportation Workers Union local that represents Southwest Airlines flight attendants."While we agree that a passenger wielding a small knife or swinging a golf club or hockey stick poses less of a threat to the pilot locked in the cockpit, these are real threats to passengers and flight attendants in the passenger cabin," Martin said.Laura Glading, president of the Association of Professional Flight Attendants at American Airlines, said she was puzzled over how the agency decided to change the rules without consulting flight attendant unions."In addition to being industry stakeholders, first responders, and Sept. 11 victims, flight attendants are a resource," Glading said. "Nobody knows what it takes to keep passengers safe better than we do."Changes removing items like sporting goods from the prohibited list are based on recommendations from a TSA working group that's trying to weed out commonly confiscated items that don't present a security threat, agency spokesman David Castelveter said."These are popular items we see regularly," Castelveter said. "They don't present a risk to transportation security."Pistole, the former No. 2 official at the FBI, has stressed the use of intelligence and "risk-based" security during his tenure leading the TSA. The agency is moving away from uniform procedures that apply to every passenger and toward efforts to perform background checks on passengers before they arrive at an airport.Overseas passengers will no longer have to check the qualifying knives as they pass through the U.S.The agency will still prohibit some knives, including those with locking blades or molded handles, like those used by hunters for skinning, Pistole said.Box cutters, like those used by the Sept. 11 terrorists, and razor blades will still be banned."The sensitivity to those who were attacked on 9-11 still resonates strongly," Pistole said. "There's just too much emotion associated with them, particularly the box cutters."Staff writer Andrea Ahles contributed to this report.