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Safety Recommendation Details

Safety Recommendation A-81-075
Details
Synopsis: ON JANUARY 20, 1981, CASCADE AIRWAYS FLIGHT 201, A BEECH 99 OPERATING FROM MOSES LAKE TO SPOKANE, WASHINGTON, CRASHED ABOUT 4.5 MILES SOUTHWEST OF SPOKANE INTERNATIONAL AIRPORT. THE AIRCRAFT CRASHED WHILE THE PILOT WAS MAKING A LOCALIZER APPROACH TO RUNWAY 3. SEVEN PEOPLE WERE KILLED, INCLUDING THE FLIGHTCREW, AND TWO PASSENGERS WERE INJURED SERIOUSLY.
Recommendation: TO THE FEDERAL AVIATION ADMINISTRATION: Establish for aircraft used in commercial operation the maximum cockpit noise levels which will permit adequate direct voice communication between flight crewmembers under all operating conditions. (Superseded by A-86-112-A-86-113)
Original recommendation transmittal letter: PDF
Overall Status: Closed - Unacceptable Action/Superseded
Mode: Aviation
Location: Spokane, WA, United States
Is Reiterated: Yes
Is Hazmat: No
Is NPRM: No
Accident #: DCA81AA006
Accident Reports: Cascade Airways, Inc., Beechcraft 99A, N390CA
Report #: AAR-81-11
Accident Date: 1/20/1981
Issue Date: 7/28/1981
Date Closed: 10/9/1986
Addressee(s) and Addressee Status: FAA (Closed - Unacceptable Action/Superseded)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 10/9/1986
Response: From the greensheet issuing A-86-98-118: In the two accidents involving Beech 99 airplanes, inadequate flightcrew coordination procedures may have been a factor. Also, excessive cockpit noise levels probably adversely affected the ability of the flightcrews to communicate. Both flights were operated under the provisions of 14 CFR Part 135.99 which require the use of two pilots. Further, the flight manuals of both carriers require specific flightcrew coordination procedures. However, neither airplane had an interphone system and such a communication system was not required by regulation. The Safety Board found that the flightcrews of both Henson and Bar Harbor Airlines used hand signals to communicate certain routine information. Although the single hand signal (to reduce power after takeoff) used by Henson pilots was not sanctioned by the operations manual, it was taught in flight training. Bar Harbor pilots used hand signals to identify altitudes but these were not officially acknowledged in the operations manual. In 1981, as a result of a Cascade Airways Beech 99 accident in Spokane, Washington, in which the cockpit's noise level was an issue, the Safety Board recommended that the FAA establish maximum cockpit noise levels which will permit adequate direct voice communication between flightcrews (Safety Recommendation A-81-75). The Safety Board also recommended that the FAA require the installation and use of crew interphone systems in the cockpits of those aircraft in which noise levels reach or exceed the maximum established noise levels (Safety Recommendation A-81-76). In response to Safety Recommendation A-81-75, the FAA issued a report on July 19, 1982, in which a preferred frequency speech interference level (PSIL) E/ of 78 was cited as the preferred maximum noise level in commercial transport cockpits. The FAA stated in its response to the Safety Board that it would issue an Advisory Circular (AC) on this issue. The Safety Board placed Safety Recommendation A-81-75 in an “Open-Acceptable Alternate Action" status. To date, no such AC has been issued, although the Safety Board is aware that a draft AC has been in circulation for almost a year. In its response to Safety Recommendation A-81-76, the FAA stated, "We have been unable to locate a significant historical data base where cockpit noise interference with crew duties was a probable cause. Therefore, we believe that any economic burden placed on the aviation community in this regard cannot be justified on a cost-benefit basis." Safety Recommendation A-81 -76 also was placed in an "Open-Acceptable Alternate Action" status. As a result of its investigation of the Henson and the Bar Harbor accidents, the Safety Board has reevaluated its position on the FAA's response to Safety Recommendations A-81-75 and -76. The Board believes that excessive Beech 99 cockpit noise levels precluded effective oral communication and contributed to a reduction in communications between the flightcrews in these accidents. Consequently, the noise levels interfered with proper and timely crew coordination. In a full-mission simulation study conducted at the National Aeronautics and Space Administration, researchers found that, "when more information was transferred regarding aspects of flight status, few errors appeared which were related to systems operation (e.g….misreading and missetting of instruments…Overall there was a tendency for crews who did not perform as well to communicate less-a finding which underscores the importance of the information transfer process." The Safety Board agrees with this assessment. Consequently, the Safety Board finds that the FAA's proposal to issue an AC on cockpit noise levels is no longer an acceptable response to Safety Recommendations A-81-75 and -76, although it still believes the issuance of the AC to be an appropriate action. Therefore, the Board has classified Safety Recommendations A-81-75 and -76 as "Closed-Unacceptable Action/Superseded," and it has issued two new recommendations (A-86-112 and A-86-113) to the FAA based on the maximum cockpit noise level of 78 PSIL recommended in the FAA contract report. The Safety Board believes also that the FAA should not allow flights to be dispatched without a functioning interphone system. Therefore, the Board believes that the interphone system, when installed, should be removed from the Master Minimum Equipment List.

From: NTSB
To: FAA
Date: 9/30/1986
Response: From the accident report of Bar Harbor Airlines flight 1808, a Beech BE-99, N300WP, Auburn-Lewiston Municipal Airport in Auburn, Maine on August 25, 1985. The Board adopted this report on 9/30/1986. As a result of its investigation, the Safety Board reiterated the following recommendations to the Federal Aviation Administration: A-81-75, A-81-76, A-82-107, A-82-109, A-82-110, and A-82-111.

From: FAA
To: NTSB
Date: 11/29/1985
Response: A draft advisory circular (AC) has been coordinated within the FAA, and the comments received are being incorporated. I plan to announce in the Federal Register the Data Source: NTSB Recommendations to FAA and FAA Responses availability of the proposed AC for public review and comment with a scheduled completion in May 1986. The AC will furnish guidance on the measurement and analysis of cockpit noise and remedies to improve communications in cockpits with high noise levels. I will keep the Board advised of any significant actions.

From: NTSB
To: FAA
Date: 1/30/1984
Response: The Safety Board appreciates receiving a copy of the FAA's engineering study on cockpit communication interference for its files. As stated in the Board's letter of July 29, 1983, Safety Recommendation A-81-75 and -76 will be maintained in an "Open--Acceptable Alternate Action" status pending issuance of the Advisory Circular.

From: FAA
To: NTSB
Date: 9/19/1983
Response: FAA LETTER: ENCLOSED FOR THE BOARD'S INFORMATION AND FILE IS A COPY OF THE ENGINEERING STUDY ON THE COCKPIT NOISE LEVEL REQUESTED IN YOUR JULY 29, 1983, LETTER. PLEASE BE ADVISED THAT WE HAVE NOT CONDUCTED A FORMAL COST-BENEFIT ANALYSIS. WE HAVE BEEN UNABLE TO LOCATE A SIGNIFICANT HISTORICAL DATA BASE WHERE COCKPIT NOISE INTERFERENCE WITH CREW DUTIES WAS A PROBABLE CAUSE. THEREFORE, WE BELIEVE THAT ANY ECONOMIC BURDEN PLACED ON THE AVIATION COMMUNITY IN THIS REGARD CANNOT BE JUSTIFIED ON A COST-BENEFIT BASIS. WE ARE PROCEEDING WITH THE DEVELOPMENT OF THE ADVISORY CIRCULAR (AC) NOTED IN OUR LETTER DATED FEBRUARY 9, 1983.

From: NTSB
To: FAA
Date: 7/29/1983
Response: The Safety Board is pleased to learn that the FAA will be developing an Advisory Circular which will provide guidance on cockpit noise measurement, noise levels above which communication aids would be desirable, and remedies that can be used in the event that high noise levels are encountered. In view of the issue raised by the FAA concerning the economic burden if intercommunications systems were made mandatory, the Safety Board will accept issuance of an Advisory Circular as fulfilling the intent of the Board's recommendations. The Board requests copies for its records of the documentation of FAA's engineering study on this subject and the cost-benefit analysis referred to in your response. Pending issuance of the Advisory Circular, Safety Recommendations A-81-75 and -76 will be maintained in an "Open--Acceptable Alternate Action" status.

From: FAA
To: NTSB
Date: 2/9/1983
Response: FAA LETTER: WE HAVE COMPLETED OUR ENGINEERING STUDY ON THIS SUBJECT. THE STUDY CONFIRMED THAT THERE ARE A FEW AIRCRAFT THAT HAVE COCKPIT NOISE LEVELS HIGH ENOUGH TO CAUSE INTERFERENCE WITH VERBAL CREW COMMUNICATION. THE FAA DOES NOT BELIEVE, HOWEVER, THAT REQUIRING THE INSTALLATION AND USE OF A CREW INTERPHONE SYSTEM IN THESE AIRCRAFT IS WARRANTED AT THIS TIME, SINCE IT WOULD PLACE AN ECONOMIC BURDEN ON SOCIETY WITHOUT YIELDING A CORRESPONDING INCREASE IN SAFETY BENEFITS. THEREFORE, WE ARE PROCEEDING WITH THE DEVELOPMENT OF AN ADVISORY CIRCULAR (AC) WHICH WILL PROVIDE GUIDANCE ON COCKPIT NOISE MEASUREMENT, NOISE LEVELS ABOVE WHICH COMMUNICATION AIDS WOULD BE DESIRABLE, AND REMEDIES THAT CAN BE USED IN THE EVENT THAT HIGH NOISE LEVELS ARE ENCOUNTERED. WE BELIEVE THAT THIS AC WILL MEET THE INTENT OF THESE RECOMMENDAIONS.

From: NTSB
To: FAA
Date: 11/24/1982
Response: Your response of October 27, 1981, indicated that the FAA's Office of Aviation Medicine would conduct a Research, Development, and Engineering study on the issue of maximum cockpit noise levels for adequate flightcrew direct voice communication and that we would be informed of the findings resulting from this study. We now request an updated status report. Both recommendations remain in an "Open-- Acceptable Action" status.

From: NTSB
To: FAA
Date: 11/13/1981
Response: The Safety Board is pleased to note that in response to these recommendations (A-81- 75 & 76) the FAA's Office of Aviation Medicine will conduct a Research, Development, and Engineering (RD&E) study on the issue of maximum cockpit noise levels for adequate flightcrew direct voice communication. We will await the results of this study and subsequent FAA response to the problem. We trust that those involved in the RD&E study and resolution of this recommendation fully understand that existing rules requiring crew coordination are weak when noise levels hinder effective pilot-to-pilot communication. Pending the FAA's further response, both recommendations are classified in an "Open--Acceptable Action" status.

From: FAA
To: NTSB
Date: 10/27/1981
Response: FAA LTR: THE FAA CONCURS IN THE INTENT OF THIS RECOMMEN DATION. BECAUSE OF THE MANY VARIABLES ASSOCIATED WITH THE ESTABLISHMENT OF A NOISE LEVEL, WE HAVE ASKED OUR OFFICE OF AVIATION MEDICINE TO CONDUCT A RESEARCH, DEVELOPMENT, AND ENGINEERING (RD&E) EFFORT ON THIS SUBJECT. SOME OF THE VARIABLES ASSOCIATED WITH THE PROJECT ARE NOISE MEASUREMENT UNIT (METRIC), NOISE MEASUREMENT METHODOLOGY, ACCEPTABLE INTELLIGIBILITY LEVEL, AND THE DEGREE OF RAISED VOICE LEVEL FOR COMMUNICATION.