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Safety Recommendation Details

Safety Recommendation A-00-041
Details
Synopsis: ON 2/9/98, A BOEING 727, REGISTRATION NO. N845AA, OPERATING AS AMERICAN AIRLINES FLIGHT 1340, CRASHED SHORT OF THE RUNWAY WHILE ON A COUPLED INSTRUMENT LANDING SYSTEM (ILS) CATEGORY II APPROACH TO RUNWAY 14R AT CHICAGO O'HARE INTERNATIONAL AIRPORT (ORD). THE APPROACH WAS NORMAL UNTIL THE AIRPLANE PASSED THROUGH 200 FEET ABOVE GROUND LEVEL (AGL), WHERE THE AIRPLANE STARTED A PITCH OSCILLATION THAT GREW IN TIME. THE AIRPLANE DESCENDED BELOW THE ILS GLIDE SLOPE, THEN CLIMBED ABOVE IT, AND FINALLY DESCENDED BELOW IT AGAIN, IMPACTING THE GROUND 300 FEET SHORT OF THE RUNWAY THRESHOLD. UPON IMPACT, THE AIRPLANE SLID OVER THE THRESHOLD AND THEN OFF THE RIGHT SIDE OF THE RUNWAY, WHERE IT CAME TO REST. THE AIRPLANE WAS EXTENSIVELY DAMAGED, AND 22 PASSENGERS AND 1 FLIGHT ATTENDANT SUSTAINED MINOR INJURIES.
Recommendation: THE NTSB RECOMMENDS THAT THE FAA: REQUIRE OPERATORS OF BOEING 727 AIRCRAFT EQUIPPED WITH SPERRY AEROSPACE SP-50 AND SP-150 AUTOPILOTS TO PERFORM THE MODIFICATIONS DESCRIBED IN SPERRY SERVICE BULLETIN (SB) 21-1132-121 (FOR SP-50 AUTOPILOTS) AND SB 21-1132-122 (FOR SP-150 AUTOPILOTS) IF THESE 727 AIRCRAFT ARE USED FOR COUPLED INSTRUMENT LANDING SYSTEM CATEGORY II APPROACHES AT FLAP SETTINGS LESS THAN 40.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: CHICAGO, IL, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA98MA023
Accident Reports: Ground Impact of American Airlines 1340
Report #: AAB-01-01
Accident Date: 2/9/1998
Issue Date: 6/1/2000
Date Closed: 1/14/2004
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Autopilot

Safety Recommendation History
From: NTSB
To: FAA
Date: 1/14/2004
Response: The Safety Board notes that Airworthiness Directive (AD) 2003-11-19 was published July 16, 2003. This AD, applicable to certain Boeing Model 727-100 and 727-200 series airplanes, requires, under certain conditions, replacement of the installed autopilot pitch control computer with a modified computer, testing of the modified system, and revision to the airplane flight manual. The publication of this AD meets the intent of Safety Recommendations A-00-41 and -42, which are classified "Closed--Acceptable Action."

From: NTSB
To: FAA
Date: 3/5/2002
Response: The AD that the NPRM proposes to adopt is fully responsive to the recommendations. Pending final issuance of the AD, Safety Recommendations A-00-41 and -42 remain classified "Open--Acceptable Response."

From: FAA
To: NTSB
Date: 10/24/2001
Response: Letter Mail Controlled 10/29/2001 2:29:16 PM MC# 2010880: On August 31, 2001, the Federal Aviation Administration (FAA) issued a notice of proposed rulemaking (NPRM) proposing to adopt an airworthiness directive (AD) applicable to Boeing 727-100 and 727-200 series airplanes. The NPRM proposes to incorporate a faster gain schedule for faster approach in response to Safety Recommendation A-00-41 and operating limitations that will mitigate pitch excursions on coupled Category II approaches for the Boeing 727 airplanes in response to Safety Recommendation A-00-42. Specifically, the NPRM proposes the following operating limitations: * Revise the Limitations Section of the Airplane Flight Manual to limit the approved approach flap setting to 30 degrees when conducting a Category II autopilot coupled instrument landing system approach. * Inhibiting Category II autopilot coupled instrument landing system approach if the middle marker system is inoperative. * Requiring disconnect of the autopilot at or prior to 80 feet (above the runway's touchdown zone elevation) during Category II autopilot coupled instrument landing system approaches. I have enclosed a copy of the NPRM for the Board's information. I will provide the Board with a copy of the final AD as soon as it is issued.

From: NTSB
To: FAA
Date: 8/20/2001
Response: The Safety Board believes that these actions will meet the intent of both safety recommendations and appreciates the effort that the FAA has undertaken to coordinate with Boeing to revise the operating limitations for the 727 airplane. Pending issuance and analysis of the NPRM and final rule that address the recommended actions, Safety Recommendations A-00-41 and A-00-42 remain classified "Open--Acceptable Response."

From: FAA
To: NTSB
Date: 6/12/2001
Response: Letter Mail Controlled 06/15/2001 4:32:32 PM MC# 2010503: The Federal Aviation Administration (FAA) completed its evaluation and plans to issue a notice of proposed rulemaking (NPRM) to address these safety recommendations. The NPRM will propose to incorporate a faster gain schedule for faster approach in response to Safety Recommendation A-00-41 and operating limitations that will mitigate pitch excursions on coupled Category II approaches for the Boeing 727 airplanes in response to Safety Recommendation A-00-42. The proposed operating limitations will include: · A change in the Airplane Flight Manual to limit the approved approach flap setting to 30 degrees, which is appropriate for the gain schedule that will be proposed by the NPRM. · Inhibiting Category II autopilot coupled instrument landing system approach if the middle marker system is inoperative. · ?Requiring disconnect of the autopilot at or prior to 80 feet during coupled instrument landing system Category II approaches. The FAA is working closely with Boeing to develop revised operating limitations. However, additional analysis and simulations are necessary to consider additional aspects like winds, airspeeds, flap settings, glide slope angles, and/or other parameters that could adversely affect autopilot performance and safety of flight. It is anticipated that the NPRM will be issued by December 2001. I will provide the Board with a copy of the NPRM as soon as it is issued.

From: NTSB
To: FAA
Date: 1/30/2001
Response: The FAA reports that it completed its evaluation of this safety recommendation and plans to issue a notice of proposed rulemaking (NPRM) proposing to perform the modifications described in Sperry SB 21-1132-121 for SP-50 autopilots and SB 21-1132-122 for SP-150 autopilots. The FAA also reports that the Airplane Flight Manual (AFM) will be changed to limit the approved flap setting to less than 40 degrees for coupled instrument landing system Category II approaches. The Safety Board notes that this response meets the intent of this recommendation. Pending implementation of a requirement for the modification described in the Sperry SBs, Safety Recommendation A-00-41 remains classified "Open-Acceptable Response."

From: FAA
To: NTSB
Date: 11/24/2000
Response: Letter Mail Controlled 11/28/2000 3:45:19 PM MC# 2001744 The Federal Aviation Administration (FAA) has completed its evaluation of this safety recommendation and plans to issue a notice of proposed rulemaking (NPRM) proposing to perform the modifications described in Sperry Service Bulletin (SB) 21-1132-121 for SP-50 autopilots and SB 21-1132-122 for SP-150 autopilots. These SB's change the time-based gain schedule and reduce the autopilot's pitch sensitivity at low altitude. In addition, the Airplane Flight Manual (AFM) will be changed to limit the approved flap setting to less than 40 degrees for coupled instrument landing system Category II approaches. I will provide the Board with a copy of the NPRM as soon as it is issued.

From: NTSB
To: FAA
Date: 11/13/2000
Response: The FAA is working with the Boeing Company, Sperry Aerospace, and some airlines to gather the required engineering data on aircraft equipped with Sperry Aerospace SP-50 and SP-150 autopilots to address these safety recommendations effectively. Since the Boeing 727 was originally delivered 21 years ago, airlines (including American Airlines) have made several modifications to the autopilot configuration. The FAA will analyze the engineering data and develop an appropriate course of action to address any safety issue found. Although the action being taken by the FAA is responsive to these recommendations, the Board is concerned about the timeliness of this action, and believes the FAA could be requiring that airlines currently perform the modifications described in the Sperry Service Bulletins, which were issued before the safety recommendation. Despite the delay, pending completion of the FAA's evaluation and its initiation of appropriate actions identified in that evaluation, Safety Recommendations A-00-41 and A-00-42 are classified "Open-Acceptable Response."

From: FAA
To: NTSB
Date: 8/9/2000
Response: Letter Mail Controlled 08/14/2000 3:27:27 PM MC# 2001057 The Federal Aviation Administration (FAA) is working with The Boeing Company, Sperry Aerospace, and some airlines to gather the required engineering data on aircraft equipped with Sperry Aerospace SP-50 and SP-150 autopilots to address these safety recommendations effectively. The Boeing 727 was originally delivered 21 years ago, and since then, airlines, including American Airlines, have made several modifications to the autopilot configuration. The FAA will analyze the engineering data and develop an appropriate course of action to address any safety issue found. It is anticipated that the evaluation will be completed and an appropriate course of action identified by October 2000.