Mode of access: Internet at the FAA web site. Address as of 3/17/09: http://www.airweb.faa.gov/Regulatory%5Fand%5FGuidance%5FLibrary/rgAdvisoryCircular.nsf/0/147838ecc39e3f3b86256f3a00662e0a/$FILE/150-5100-17chg2.pdf; current access available via PURL.