Interpretation ID: nht79-4.49

DATE: 05/23/79

FROM: J. C. ECKHOLD DIRECTOR AUTOMOTIVE SAFETY OFFICE

TO: JOAN B. CLAYBROOK -- ADMINISTRATOR NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

TITLE: REQUEST FOR CLARIFICATION OF DAYLIGHT CONDITIONS FEDERAL MOTOR VEHICLE SAFETY STANDARD 101-80; CONTROLS AND DISPLAYS (DOCKET NO. 1-18; NOTICE 13)

ATTACHMT: LETTER DATED 7/20/79 [EST] FROM FRANK BERNDT, CHIEF COUNSEL OF NHTSA TO J. C. ECKHOLD OF FORD MOTOR COMPANY

TEXT: In considering various aspects of Federal Motor Vehicle Safety Standard (FMVSS) 101-80 (43 Fed. Reg. 27541, dated June 26, 1978) Ford Motor Company (Ford) seeks clarification of certain portions of Section 5.3.3.

That portion of Section 5.3.3 for which Ford seeks clarification reads in pertinent part:

". . . The light intensity of each tell-tale shall not be variable and shall be such that, when activated, that tell-tale and its identification are visible to the driver under all daytime and nighttime conditions. . . ." (Emphasis added.)

Ford testing experience indicates that under certain possible, but infrequent, morning or evening sun lighting conditions the angle, intensity and color characteristics of sun lighting may cause transitory reflection characteristics that obscure either the intensity or color, or both, of the required tell-tale indicators at times when the angle of reflected sunlight is virtually the same as the viewing angle of the driver.

Because tell-tale illumination level may not be variable, tell-tale intensity must represent a compromise between daytime and nighttime visibility requirements.

Ford suggests that consideration be given to issuing clarifying language to specify that the situations as described are not intended to be included in the requirement that tell-tale indicators must be visible under all daytime and nighttime conditions.

Your early consideration of this request will be appreciated.

Very truly yours,