Automatic landing systems (ALS).

Bibliographic Details
Corporate Author:	United States. Federal Aviation Administration
Format:	Government Document Book
Language:	English
Published:	Washington, D.C. : Dept. of Transportation, Federal Aviation Administration, [1971]
Series:	Advisory circular ; AC no: 20-57A
Subjects:	Airplanes > Landing gear.
Online Access:	https://purl.fdlp.gov/GPO/LPS103299

Description
Item Description:	AC Number 20-57, dated 29 January 1968, is cancelled. Title from PDF file caption (viewed Sept. 29, 2008). Electronic resource.
Physical Description:	4, 3 pages : digital, PDF file.
Format:	Mode of access: Internet at the FAA web site. Address as of 9/29/08: http://www.airweb.faa.gov/Regulatory%5Fand%5FGuidance%5FLibrary/rgAdvisoryCircular.nsf/0/42e37eb57306dedf86256a8600456fbb/$FILE/ac20-57a.pdf ; current access available via PURL.