FEDERAL AVIATION AGENCY
Washington, DC 20553
Mr. Leon H. Tanguay
Director, Bureau of Safety
Civil Aeronautics Board
Washington, D. C. 20428
Dear Mr. Tanguay:
This will supplement our January 2, 1964, acknowledgment to your Letter,reference B-80-95, dated December 11, 1963, regarding the Pan American World Airways, Inc, Beoing 707-121, N709PA, aircraft accident near Elkton, Maryland, on December 8, 1963.
The recommendations and suggestions offered in your letter of December 17,1963, have been carefully considered along with other ideas for achieving improved protection against lightning stakes. The Agency is engaged in a program of studies, tests, and investigations to provide information essential to the development and application of superior protective measures.
Although the investigation of the accident has not yet disclosed evidence of the mechanism by which a lightning strike ignited the fuel, we have applied certain precautionary measures, each of which offers some degree of benefit. These are:
NOTAM issued on December 13, 1963, alerting pilots and traffic controllers to lightning hazards, need for thunderstorm avoidance, and encouraging use of PIREPS.
Telegram to air carriers and aircraft operators, on December 18, 1963, recommending the installation of static discharges on all aircraft using turbine fuels.
Airwothiness Directive on Boeing 707, 720, and 727 series aircraft, requiring modification of of fuel tank access door bonding, issued on February 4, 1964, as an adopted rule.
Airworthiness Directive on Boeing 707 and 720 series aircraft, requiring overlay on surge tank skin for improved protection against penetration, issued on February 21, 1964, as an adopted rule.
