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On March 5, 2015, at 1102 eastern standard time, Delta Air Lines flight 1086, a Boeing MD-88, N909DL, was landing on runway 13 at LaGuardia Airport (LGA), New York, New York, when it departed the left side of the runway, contacted the airport perimeter fence, and came to rest with the airplane’s nose on an embankment next to Flushing Bay. The 2 pilots, 3 flight attendants, and 98 of the 127 passengers were not injured; the other 29 passengers received minor injuries. The airplane was substantially damaged. Flight 1086 was a regularly scheduled passenger flight from Hartsfield-Jackson Atlanta International Airport, Atlanta, Georgia, operating under the provisions of 14 Code of Federal Regulations Part 121. An instrument flight rules flight plan had been filed. Instrument meteorological conditions prevailed at the time of the accident.
TO THE BOEING COMPANY: Collaborate with the Federal Aviation Administration and US operators of MD-80 series airplanes to (1) conduct a study to examine reverse thrust engine pressure ratio (EPR)-related operational data, procedures, and training and (2) identify industry-wide best practices that have been shown to be effective in reliably preventing EPR exceedances to mitigate the risks associated with rudder blanking.
Original recommendation transmittal letter:
Open - Acceptable Response
New York, NY, United States
Runway Excursion During Landing Delta Air Lines Flight 1086 Boeing MD-88, N909DL, New York, New York March 5, 2015
Addressee(s) and Addressee Status:
Boeing Company (Open - Acceptable Response)
Safety Recommendation History
We note that you are working with the FAA and several MD-80 operators to examine reverse thrust EPR-related operational data, procedures, and training and to identify industry-wide best practices that will prevent EPR exceedances and mitigate the risks associated with rudder blanking. We also note that, in response to A-16-31, you issued two temporary revisions (TRs) that add (1) a checklist item to the “descent/approach” procedures for the flight crew to identify and confirm appropriate reverse thrust EPR for reported runway conditions (1.6 EPR or 1.3 EPR), and (2) a checklist item to the “landing roll” procedures for the pilot not flying to call out the EPR values as they approach or exceed EPR limits appropriate for the briefed runway conditions. We do not consider the TRs to be an alternative to the action recommended in A-16-31, as you proposed; however, we believe that they could be part of the solution that is developed in response to A-16-30. Pending our receipt and review of the findings from your study and completion of the recommended actions, Safety Recommendation A-16-30 is classified OPEN--ACCEPTABLE RESPONSE.
-From Hillary D. Barr, Director, Product Safety, Chief Engineer, Air Safety Investigation: Boeing is supporting the collaborative effort discussed in safety recommendation A-16-30. Communication has taken place between the FAA, several MD-80 operators and Boeing. A meeting with all stakeholders has been scheduled for January 2017. In response to safety recommendation A-16-31, Boeing has considered the feasibility and propriety incorporating an advisory alert in MD-80 series models to aid pilots in avoiding engine pressure ratio (EPR) exceedances during reverse thrust operations on dry (1.6 EPR) and wet or contaminated (1.3 EPR) runway conditions. As you are aware, these values have been established to ensure rudder effectiveness. Service history has shown that exceeding these values has resulted in ‘rudder blanking’ and been a factor in runway excursions. Boeing believes that the complexity of installing such an alert (a blue advisory light) in the flight deck instrument panel somewhere in the proximity of the left/right or center main instrument panel and in view of either pilot would not be a practicable approach based on: • To be effective, any such alert would need to be able to distinguish between dry and contaminated runways in order to provide an alert when the appropriate EPR limits had been reached and/or exceeded. Such an alert would be complex to design and implement and would involve, at a minimum: o Modification of the interface with the air/ground logic o Modification of the interface with the EPR indicating system o A means to select whether the runway conditions are dry or wet/contaminated (e.g., a switch, manually selected by a flight crew member) that would have to be selected at a point in the approach/landing that would increase crew workload and potentially provide opportunities for erroneous selection of runway conditions that could mislead the crew at the point of landing/rollout. o Maintenance action to maintain operability of this ‘system’ by periodic inspections based on the design’s estimated reliability. o Consideration of whether MMEL dispatch capability would be required in the event of ‘system’ inoperability. o To also include an aural alert in combination with a visual alert would add further complexity to the design. Each of these design, operational, and maintenance changes could introduce the possibility of unintended errors and/or consequences that could affect flight safety. • Further, the introduction of an advisory light on the flight deck instrument panel and introduce human factors complexity which may diminish or erode any operational benefits: • A light in the location identified may not be easily observed by either pilot since it would be in limited space under the glare shield. o Crew monitoring the alert could be a distraction due to its location during the critical initial touchdown/landing rollout that would be over-and-above current crew duties, a human factors concern. o Requiring the pilot not flying (PNF) to monitor this alert would be added workload that diverted his or her attention from the current duty to inform and confirm to the pilot flying (PF) that ground spoilers have/have not been extended and whether/or not reverse thrust is available after touchdown. Boeing believes that an alternate approach to meeting the NTSB objective of this safety recommendation is appropriate. It has revised two operational procedures to address these issues. First, Boeing has revised the current Descent/Approach procedures. The current procedure includes a Landing Data and Briefing that has been revised to include an additional item for the flight crew to identify and confirm the appropriate reverse thrust limit for reported runway conditions (1.6 EPR or 1.3 EPR). Second, Boeing has revised the current Landing Roll procedures. The current procedure requires the PNF to announce the availability of reverse thrust. That procedure has been revised to require the PNF to call out the EPR values as they approach or exceed EPR limits appropriate for the briefed runway conditions. Such a PNF call-out solution is consistent with human factors information processing and workload considerations on the flight deck during landing. We believe these revised procedures address the NTSB’s recommendations. Accordingly, Boeing has issued two Temporary Revisions (TRs) and a new Operations Bulletin to the MD-80 model Flight Crew Operating Manual (FCOM) as follows: • TR 80-2-144 dated October 13, 2016; Includes an additional item in the Landing Data and Briefing step in the Descent/Approach Expanded Procedures checklist for the flight crew to identify and confirm appropriate reverse thrust EPR for reported runway conditions • TR 80-2-148, dated December 19, 2016; Adds an introductory sentence ‘After reverse thrust is verified…’ on the Landing Roll Expanded Procedures checklist that states: “PNF callout reverse thrust EPR values as they approach, or exceed EPR limits appropriate for the briefed runway conditions. Observe the following limitations:…”. • Operations Bulletin 80-2-015, dated December 19, 2016; Reverse Thrust EPR Control. This bulletin is similar in its message as Boeing’s Flight Operations Bulletin (FOB) MD-80-02-03, ATA: 78-30, Thrust Reverser, dated November 11, 2002.
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