Also would you have a citation or link to the 1961 law about detectors before boarding an aircraft.
The 1961 law made hijacking a federal crime and implemented some basic screening requirements. Where I found the 1st mention of screening equipment was in 1970 in a decree by Nixon. But with a stroke of luck following the clues in your 1973 121.538 link, I think I found a citation that will answer all of your questions.
I can’t get the link to post at the moment, but I found an Appellate court opinion that references a makeshift timeline in the footnotes on passenger screening and the use of metal detecting equipment.
Basically in Feb 1972 the use of metal detecting equipment was codified, but on or about Dec 5th became mandatory to be used… provided it was available.
I copied some of the footnotes below for reference and will post the link to the entire document when I can.
1970 Nixon:
I have directed the Departments of Transportation, Treasury, and Defense, the Central Intelligence Agency, the Federal Bureau of Investigation, the Office of Science and Technology, and other agencies to accelerate their present efforts to develop security measures, including new methods for detecting weapons and explosive devices. At the same time, the Departments of Defense and Transportation will work with all U. S. airlines in determining whether certain metal detectors and x-ray devices now available to the military could provide immediate improvement in airport surveillance efforts. To facilitate passenger surveillance, appropriate agencies of the Federal Government will intensify their efforts to assemble and evaluate all useful intelligence concerning this matter and to disseminate such information to airlines and law enforcement personnel
Feb 1972 FAA Press release:
See FAA Press Release No. 72-26 (Feb. 6, 1972):
"Secretary of Transportation John A. Volpe announced today that 200 FAA security officers have been ordered into the field to assist with implementation of a new regulation requiring mandatory screening of all airline passengers before flight. The new FAA regulation-which went into effect at 12 midnight Saturday-applies to all scheduled flag, domestic and intrastate air carriers. They are required to screen all passengers on all flights using one or more of the following systems: behavorial profile, magnetometer, identification check, physical search.
FAA Telegram of July 18, 1972.
FOR 100% PASSENGER SCREENING OF NON-RESERVATION (SHUTTLE) TYPE FLIGHTS, THE FOLLOWING ARE MINIMUM ACCEPTABLE PROCEDURES, EFFECTIVE IMMEDIATELY.
1 WHERE METAL DETECTORS ARE AVAILABLE
A. EACH CERTIFICATE HOLDER SHALL PREVENT THE CARRIAGE ABOARD ITS AIRCRAFT OF BAGGAGE ON OR ABOUT THE PERSON OF PASSENGERS UNLESS THAT BAGGAGE HAS BEEN EXAMINED BY A RESPONSIBLE REPRESENTATIVE OF THE CERTIFICATE HOLDER OR A LAW ENFORCEMENT OFFICER AND,
B. THE CERTIFICATE HOLDER SHALL REQUIRE EACH PASSENGER TO CLEAR THROUGH A METAL DETECTOR WITHOUT INDICATION OF UNACCOUNTED FOR METAL ON HIS PERSON PRIOR TO BOARDING.
2 WHERE METAL DETECTORS ARE NOT AVAILABLE
A. EACH CERTIFICATE HOLDER SHALL PREVENT THE CARRIAGE ABOARD ITS AIRCRAFT OF BAGGAGE ON OR ABOUT THE PERSON OF PASSENGERS UNLESS THAT BAGGAGE HAS BEEN EXAMINED BY A RESPONSIBLE REPRESENTATIVE OF THE CERTIFICATE HOLDER OR A LAW ENFORCEMENT OFFICER AND,
B. THE CERTIFICATE HOLDER SHALL REQUIRE EACH PASSENGER TO PRESENT TWO ACCEPTABLE FORMS OF IDENTIFICATION.
C. IN THE CASE OF A PASSENGER WHO DOES NOT PROVIDE ADEQUATE IDENTIFICATION, THE CERTIFICATE HOLDER MAY REQUEST THAT PASSENGER TO SUBMIT TO A CONSENT SEARCH OF HIS PERSON AND,
D. THE CERTIFICATE HOLDER SHALL DENY BOARDING TO EACH PASSENGER WHO FAILS TO COOPERATE.
THE ABOVE PROCEDURES MUST BE INCLUDED IN THE SECURITY PROGRAMS OF THE AFFECTED AIR CARRIERS. PRINCIPAL SECURITY AGENTS SHOULD IMMEDIATELY NOTIFY THE CARRIERS OF THE PROCEDURAL CHANGES INDICATED ABOVE."
DOT Directive (in part) Aug. 1, 1972
"BECAUSE OF THE CONTINUING MENACE OF AIR PIRACY AND OTHER CRIMES ABOARD AIRCRAFT AND BECAUSE OF THE SERIOUS NATURE OF THIS THREAT TO THE SAFETY OF PERSONS AND PROPERTY, I FIND THAT AN EMERGENCY EXISTS REQUIRING IMMEDIATE ACTION WITH RESPECT TO SAFETY IN AIR COMMERCE. THEREFORE, SECURITY PROGRAMS ACCEPTABLE TO THE ADMINISTRATOR UNDER SECTION 121.538(b) OF THE FEDERAL AVIATION REGULATIONS (FAR'S) AND SECURITY PROGRAMS APPROVED UNDER SECTION 121.538(c) OF THE FAR'S ARE AMENDED TO INCLUDE THE FOLLOWING MINIMUM ACCEPTABLE PROCEDURES, EFFECTIVE IMMEDIATELY.
1 NO CERTIFICATE HOLDER SHALL PERMIT ANY PERSON WHO HAS BEEN IDENTIFIED AS A SELECTEE UNDER ITS SECURITY PROGRAM INCLUDING ADULT, CHILDREN AND INFANT PASSENGERS TRAVELING IN HIS COMPANY TO BOARD ITS AIRCRAFT, UNLESS-
A. THE CARRY-ON BAGGAGE AND OTHER ARTICLES ON OR ABOUT THE PERSON OF EACH PASSENGER HAS BEEN SEARCHED AND,
B. THE CERTIFICATE HOLDER HAS REQUIRED EACH PASSENGER TO CLEAR THROUGH A METAL DETECTOR WITHOUT INDICATION OF UNACCOUNTED FOR METAL ON HIS PERSON OR
C. IN THE ABSENCE OF A METAL DETECTOR, EACH PASSENGER HAS SUBMITTED TO A CONSENT SEARCH PRIOR TO BOARDING.