# NTSB SEA99LA014: McDonnell Douglas MD-11, N801DE, Portland, OR, November 11, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 11, 1998, 11:20 local (19:20 UTC) - Place: Portland, OR - Coordinates: 45.570053, -122.590736 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.5701&lon=-122.5907&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 124 uninjured - Status: Completed, report September 28, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 48387 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA014 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/48387/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=48387 - Page: https://openairdocs.org/ntsb/SEA99LA014 ## Probable cause The flight crew's entry of an incorrect weight figure in the Flight Management System (FMS) computer, resulting in the approach being flown at an improper (low) Vref speed and an excessively nose-high attitude through the landing flare. ## Analysis The flight crew inadvertently entered an incorrect weight figure into the Flight Management System (FMS) computer. This resulted in the approach being flown at 136 knots instead of the correct airspeed of 151 knots. At this airspeed, the aircraft proceeded along the flight path at a pitch attitude of about eight (8) degrees instead of the three or four degrees that would have occurred at the correct airspeed. At this reduced airspeed and excessive attitude, the tail clearance during the flare was reduced to the point where the airframe contacted the runway surface. ## Factual narrative On November 11, 1998, at 1120 Pacific standard time, a McDonnell Douglas MD-11, N801DE, operated by Delta Air Lines as a 14 CFR Part 121 scheduled passenger flight, experienced a tail strike while landing at Portland International Airport, Portland, Oregon. The flight was landing on runway 10R after arriving from Cincinnati, Ohio. Visual meteorological conditions prevailed, and an instrument flight plan had been filed. There were no injuries to the 11 crew members or 113 passengers, but the aircraft sustained substantial damage to the belly skin and stringers. The flight crew stated that they were unaware the aircraft had experienced a tail strike until maintenance personnel at the arrival gate advised them that there was damage to the number 3 VHF antenna and the skin aft of the antenna mount. After the passengers were deplaned normally through the jetway, the damage was further evaluated, and it was determined that the aircraft would need to be ferried to Atlanta for permanent repair. During the investigation, it was determined that the weight existing in the Flight Management System (FMS) during the approach and landing sequence was in error approximately 100,000 pounds. As confirmed by a review of the Flight Data Recorder (FDR) readout, the FMS weight was about 292,000 pounds, when in fact the actual aircraft landing weight was approximately 392,000 pounds. This error generated a final approach speed of 136 knots for an approach that should have been flown at 151 knots. This reduced speed resulted in the approach being flown at an eight (8) degree pitch attitude instead of the three to four degrees that would occur during an approach flown at the correct airspeed. The FDR data also showed that approximately 7 seconds before nose gear strut compression, the pitch attitude reached 10.9 degrees. According to the operator, while landing at this speed and attitude "... tail clearance tolerances are minimal." Although the exact FMS entry error was not determined, the most likely would be the crew missing the hundred thousand entry by one when inputting the takeoff gross weight, entering the empty weight into the zero fuel weight prompt, or entering the zero fuel weight in the aircraft takeoff gross weight prompt. According to the operator, as a result of the lessons learned from this accident, Delta Air Lines is putting additional emphasis on the MD-11 FMS loading procedures during flight training and line checks. In addition, Delta is implementing a program that stresses awareness of proper pitch attitude while in the final approach mode. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Dragged wing,rotor,pod,float or tail/skid, landing - flare/touchdown - aircraft weight and balance - inaccurate, flightcrew (cause) - airspeed(vref) - improper, flightcrew (cause) - rotation - excessive, copilot/second pilot (cause) ## Aircraft - Registration: N801DE (not matched to a registry record) - Reported make and model: McDonnell Douglas MD-11 - Category: Airplane - Serial number: 48565 - Airframe hours: 24332 - Engines: P&W PW 4460 60000 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Registered owner: Delta Air Lines, Inc. - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, November 10, 1999, 5 hours before - Departed: CVG, CINCINNATI, OH - Destination: PDX - Flight plan: IFR - Airport: PDX, Portland International, runway 10R, 11,000 × 150 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; airline transport, flight engineer, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 10,000 total, 4,082 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 140° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 6,500 ft broken - Temperature: 46 °F, dew point 43 °F - Altimeter: 30.00 inHg - Observed at: KPD, 1 nm away ## Docket (6 files) The files NTSB released with the investigation on January 26, 2000, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=48387. 1.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 438 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40456712&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Supplement E - Second Pilot Information (item 2, .PDF, 121 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40456711&FileExtension=.PDF&FileName=Supplement%20E%20-%20Second%20Pilot%20Information-Redacted.PDF - Supplement S - Aircraft Occupant and Injured Ground Personnel (item 3, .PDF, 58 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40115621&FileExtension=.PDF&FileName=Supplement%20S%20-%20Aircraft%20Occupant%20and%20Injured%20Ground%20Personnel-Master.PDF - Flight Data Recorder Factual Report (item 4, .PDF, 758 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40456713&FileExtension=.PDF&FileName=Flight%20Data%20Recorder%20Factual%20Report-Redacted.PDF - Statement of Captain (item 5, .PDF, 106 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40456714&FileExtension=.PDF&FileName=Statement%20of%20Captain-Redacted.PDF - Statement of First Officer (item 6, .PDF, 89 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40115625&FileExtension=.PDF&FileName=Statement%20of%20First%20Officer-Master.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.