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Wednesday, M ay 5, 1948

FEDERAL REGISTER

b Regardless of whether a petition Number JJ99, effective February 15, 1948.
for nonquota or preference-quota status This regulation required the installation is approved before or after July 1, 1948, of an absolute terrain proximity indica such approval may for cause be revoked tor on aircraft operated in scheduled air by the Commissioner at any time prior carrier Service carrying passengers dur to the time the beneficiary commences ing the hours of darkness or under in his journey to the United States. No strument flight rule conditions. It was such revocation, however, shall have ef provided that this regulation would ter fect unless the petitioner is notified of minate February 15, 1950. Upon peti the proposed revocation and is afforded tion of the air carriers based upon pro an opportunity to refute the evidence on curement and installation difficulties which it is predicated and unless notice which prevented compliance within the of the revocation is communicated allotted time, the Board, on February 11, 1948, extended the date for full com through the Department of State and the appropriate consular officer to the bene pliance with this requirement until May ficiary before he commences his journey 15, 1948, by means of Special Regulation to the United States. If revocation is SR-319.
The promulgation by the Board of a not accomplished in such fashion and the beneficiary applies for admission to requirement for installation of absolute the United States, the question of his terrain proximity indicator equipment admissibility shall be determined upon was based largely upon recommenda examination before an immigrant in tions made by the Presidents Special spector or before a board of special in Board of Inquiry on Air Safety on which quiry. Approvals may be reconsidered the aviation industry, as well as the by thé Commissioner on request of the Government, was represented. Infor consular officer considering the applica mation presented to the Presidents tion for the immigration visa or where Special Board and to the Civil Aeronau the propriety of reconsideration is other tics Board indicated a pressing need for wise brought to the attention of the Com such equipment, and further indicated missioner. Revocations under this para that devices of sufficient dependability graph shall be appealable as prescribed had been developed to warrant their in in Part 90 of this chapter. Sec. 9, 43 stallation as secondary navigational aids. Upon consideration of these fac Stat. 157, 50 Stat. 164; 8 U. S. C. 209
tors the Board provided that these in The rules stated above shall become dicators should be required only on effective on July 1, 1948.
scheduled air carrier aircraft carrying These rules are based on the need for passengers and only as an auxiliary aid, a detailed description of the procedure not to replace other required naviga to be followed and the requirements to tional instruments. The Board pointed be met by persons who wish to petition out that the requirement was for a for nonquota or preference quota immi limited period of two years during which gration visas and By persons who wish the practicability of the device could be to come to the United States as nonquota thoroughly tested, and an opportunity or preference quota immigrants. The provided for further development and, purpose of these rules is to make it pos refinement before any further or broader sible for all interested persons to ascer extension of the requirement would be tain such procedure and requirements.
made. The Board then felt that the Sec. 23, 39 Stat. 892, sec. 24, 43 Stat. device would not detract from, and could 166, sec. 37 a, 54 Stat. 675, sec. 1, 54 contribute substantially to, the safety of flight, especially in the avoidance of ac Stat. 1238; 8 U. S. C. 102, 222, 458
cidents resulting from failure to clear W atson B. M iller , terrain.
Commissioner of The operational experience of the sev Immigration and Naturalization.
eral air carriers which have equipped Approved: April 29, 1948.
substantial numbers of aircraft with the various models of the device now avail T om C. C lark, able does not bear out the information Attorney General.
previously presented to the Board, which P. R. Doc. 48-3947; P lied, May 4, 1948;
information was also the basis of the rec 8:48 a 5 m .
ommendations of the Presidents Special Board of Inquiry on Air Safety. Opera tional experience indicates that these in TITLE 14 CIVIL AVIATION
dicators require an unusual amount of Chapter I Civil Aeronautics Board maintenance to assure their continued Regs., Serial No. SR-320
operation. For example, one carrier re ported over 70 cases of malfunctioning P art 41C ertification and O peration for the 30 aircraft equipped with the de R ules for S cheduled A ir C arrier vice during a two-month period, or an O perations O utside C ontinental L im
average of more than one failure a day.
its of the U nited S tates Another carrier was required to change P art 61S cheduled Air C arrier R ules 177 units on 92 aircraft during a fourweek period. Such a high rate of mal rescission of requirement of absolute functioning would undoubtedly result in terrain proxim ity indicator on all numerous delays, if not cancellations of SCHEDULED AIRCRAFT CARRYING PASSEN
scheduled flights under the present regu GERS DURING HOURS OF DARKNESS OR
lation.
UNDER INSTRUMENT FLIGHT RULE CONDI
In addition, the device, which is in TIONS
Adopted by the Civil Aeronautics tended to give indications at predeter Board at its office in Washington, D. C., mined altitudes; is reported to give such indications at other than the predeter on the 29th day of April 1948.
On October 10,1947, the Board adopt mined altitudes. These erroneous indi ed Special Civil Air Regulation Serial cations may be due to equipment defl-

2413
ciencies or external causes, such as elec trical interference, rain, and wet snow.
The relative frequency of such unreliable indications has apparently caused a lack of confidence of the pilots in the device presently being used. Of particular sig nificance is the fact that certain condi tions cause an indication of altitude higher than the actual altitude, thus giving the pilot a false sense of security.
Recent tests conducted by the Technical Development Service of the Civil Aero nautics Administration confirm the fact that the indications given by the pres ently available equipment are not suffi ciently reliable.
As the Board previously indicated, one of the bases for the promulgation of the original regulation was the belief that the regulation would expedite the further development and refinement of available equipment. The equipment now in use operates on a frequency band of 420 to 460 megacycles, as authorized by the Federal Communications Com mission on a temporary basis for the proposed two-year experimental period.
However, in accordance with a recent international agreement allocating radio frequencies, we are informed by the Federal Communications Commission that authority to use this frequency band cannot be extended, and that devices such as the absolute terrain proximity Indicator will thereafter have to make use of frequencies between 4200 and 4400
megacycles. This change in frequency probably will render obsolete all equip ment currently in use. Moreover, the differences in equipment designed to use the new frequencies would be such as to nullify the benefits of much of the opera tional experience with the present equip ment.
In view of these factors, the Board does not feel justified in continuing to require the installation of the equipment which is presently available. The Board still believes that a device which would give the pilot a more definite indication not only as to his proximity to hazardous terrain and other objects, but also more complete information as to its relative location is highly desirable. It does not believe, however, that the rescission of the regulation will stop experimentation with and development of such a device by the équipment manufacturers and the air carriers. The Board intends to care fully observe the results of activity of this nature, and will take appropriate action to encourage the development and utilization of devices proven to be de pendable.
For the reasons stated above, notice and public procedure hereon are inpracticable, and the Board finds that goods cause exists for making this regulation effective on less than 30 days notice.
In consideration of the foregoing the Civil Aeronautics Board hereby rescind Special CiVAir Regulation Serial NumT
ber SR-319/13 F. R. 747 effective immediately.
Sécs. 205 &, 601, 604, 52 Stat. 984, 1007, 1010; 49 U. S. C. 425 a, 551, 554
By the Civil Aeronautics Board.
seal
M. C. M ulligan ,
Secretary.
F. R. Doc. 48-3974; F iled , May 4, 1948;
9:01 a. m .