WASHINGTON, Sept 29 (Reuters) - A group representing

major U.S. airlines warned on Monday that a partial federal

government shutdown could strain American aviation and slow

flights, as air traffic controllers and security officers would

be forced to work without pay and other functions would be

halted.

Airline trade group Airlines for America, which represents

United Airlines, Delta Air Lines ( DAL ), American

Airlines ( AAL ), Southwest Airlines ( LUV ) and others, warned

that if funding lapses "the system may need to slow down,

reducing efficiency" and impacting travelers.