Under Secretary of Transportation for Security Adm. James M. Loy today updated Transportation Security Administration (TSA) guidelines for checking baggage, saying they are important to having secure and enjoyable holiday air travel.

Adm. Loy also urged passengers to leave their checked bags unlocked, which will avoid the potential need to forcibly open bags that require further physical inspection.

He commented during a demonstration of the Jacksonville (FL) International Airport's new "in-line" explosives detection system (EDS) for screening checked baggage. The TSA will screen all checked bags by Dec. 31 -- yet another layer of security for the nation's 429 commercial airports.

"Security screening went well at Thanksgiving and we are committed to making the holiday season safe and enjoyable for air travelers, "Adm. Loy said. "Passengers can play a major role by following simple packing guidelines, and by getting to the airport on time."

Adm. Loy asked passengers to not pack food or beverages in checked bags and to pack footwear on top of other contents. Put personal belongings in clear plastic bags to reduce chances of a TSA screener having to handle them, and spread out - not stack - books.

Passengers also were warned against putting film in checked bags, because screening equipment will damage it, and to leave gifts unwrapped should screening require them to be opened. Put scissors, pocket knives and other sharp items in checked bags; never carried on. For other tips, check out www.TSATravelTips.us.

The TSA has developed bag search plans with each of the nation's airports. Besides the large EDS machines, screening will be done using congressionally approved methods including explosives trace detector machines, explosives-sniffing dogs, passenger-bag matching and hand searches.

Adm. Loy reminded passengers that all bags are subject to search. At airports like Jacksonville International, in-line systems are built into the baggage conveyer belt, which snakes through non-public areas of the airport.

Bags may have to be opened for inspection. Leaving bags unlocked will avoid the potential need for them to be opened forcibly. The 158 federal security directors are authorized to immediately respond to issues that occur at airports under their responsibility.

The TSA is moving toward providing travelers with free, padlock-like seals that screeners can snip open if a search is necessary. But for now, air travelers are advised to use cable or zip ties as an alternative to baggage locks. If a checked bag is searched, a statement to that effect will be inserted in the bag to notify the owner.