The FAA has published a Safety Alert For Operators (SAFO) urging pilots to remember to activate pilot controlled lighting (PCL) systems at non-tower airports. Apparently the agency has noted a "rising trend" of incidents in which pilots have failed to turn on the lights when landing after dark. Also as part of the SAFO, the FAA adds that pilots should "demonstrate a knowledge and proficiency in the use of the Common Traffic Advisory Frequency (CTAF) and PCL systems." At many (but not all) PCL-equipped airports, clicking the radio transmitter on the CTAF several times activates the lights. In some cases, however, night landings are authorized only by prior request (as noted in the Airport Directory). The lights are activated on a different frequency — unpublished, but available on request by telephone.