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Safety Recommendation Details

Safety Recommendation A-72-205
Details
Synopsis: ALASKA AIRLINES FLIGHT 1866, A BOEING 727, N2969G, CRASHED WHILE ATTEMPTING A NONPRECISION INSTRUMENT APPROACH TO THE JUNEAU MUNICIPAL AIRPORT, JUNEAU, ALASKA, AT APPROXIMATELY 1215 P.D.T., ON SEPTEMBER 4, 1971. THE FLIGHT HAD BEEN CLEARED FOR A LOCALIZER DIRECTIONAL AID (LDA) APPROACH TO RUNWAY 8 AND HAD REPORTED PASSING THE FINAL APPROACH FIX INBOUND TO THE AIRPORT. THIS INTERSECTION IS LOCATED 10.2 NAUTICAL MILES WEST OF THE AIRPORT. NO FURTHER COMMUNICATIONS WERE HEARD FROM THE FLIGHT. THE AIRCRAFT STRUCK A SLOPE IN THE CHILKAT MOUNTAIN RANGE AT ABOUT THE 2,500-FOOTLEVEL ON THE APPROXIMATE LOCALIZER COURSE AT A POSITION 18.5 MILES WEST OF THE AIRPORT. ALL 104 PASSENGERS AND SEVEN CREWMEMBERS WERE INJURED FATALLY. THE AIRCRAFT WAS DESTROYED. THE NATIONAL TRANSPORTATION SAFETY BOARD DETERMINES THAT THE PROBABLE CAUSE OF THIS ACCIDENT WAS A DISPLAY OF MISLEADING NAVIGATIONAL INFORMATION CONCERNING THE FLIGHT'S PROGRESS ALONG THE LOCALIZER COURSE WHICH RESULTED IN A PREMATURE DESCENT BELOW OBSTACLE CLEARANCE ALTITUDE. THE ORIGIN OF THE ERRONEOUS NAVIGATIONAL INFORMATION COULD NOT BE DETERMINED. THE BOARD FURTHER CONCLUDES THAT THE CREW DID NOT USE ALL AVAILABLE NAVIGATIONAL AIDS TO CHECK THE FLIGHT'S PROGRESS ALONG THE LOCALIZER NOR WERE THESE AIDS REQUIRED TO BE USED. THE CREW ALSO DID NOT PERFORM THE REQUIRED AUDIO IDENTIFICATION OF THE PERTINENT NAVIGATIONAL FACILITIES.
Recommendation: THE FAA CONTINUE THE TESTS NOW IN PROCESS CONCERNING EXTRANEOUS HARMONICS ON THE DOPPLER SIGNAL AND INITIATE RESEARCH INTO THEIR POSSIBLE HAZARDOUS EFFECTS ON NAVIGATION RECEIVERS AND ASSOCIATED INSTRUMENT DISPLAYS.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: Juneau, AK, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA72AZ003
Accident Reports: Alaska Airlines, Inc., Boeing 727, N2969G
Report #: AAR-72-28
Accident Date: 9/4/1971
Issue Date: 1/8/1973
Date Closed: 12/7/1973
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: FAA
To: NTSB
Date: 1/19/1973
Response: RESPONSE FROM THE FAA TO SAY THAT THEIR TESTS SHOW NO EFFECT ON A RECEIVER OF THE TYPE INVOLVED IN THE ACCIDENT INVESTIGATION DUE TO EXTRANEOUS HARMONIC RADIATION. A COMPREHENSIVE REPORT IS PRESENTLY BEING COMPILED ON THESE TESTS AND WILL BE AVAILABLE BY MARCH 1973. THEY FURTHER STATE THAT THEY ARE CONTINUOUSLY ALERT TO POSSIBLE DETRIMENTAL EFFECTS TO AIRBORNE RECEIVER OPERATION CAUSED BY MODIFICATIONS TO GROUND FACILITIES. SUCH INVESTIGATIONS WILL, THEREFORE, CONTINUE TO BE A PART OF THEIR PROGRAM FOR UPGRADING GROUND VOR STATIONS TO MEET FURTHER NEEDS.