- Date
- January 31, 2000, 16:20 local (Feb 1, 2000, 00:20 UTC)
- Place
- Port Hueneme, CA
- Injuries
- 88 fatal
- Damage
- Destroyed
- Phase of flight
- Enroute
- Aircraft
- N963ASDouglas MD-83
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 29, 2003
- Report
- Board-adopted at Board Meeting
- Investigation class
- Class 1
- NTSB office
- Major Investigations Division
- Safety recommendations
- Yes
- FAA report
- 20000131004739A
- Case key
- 48551
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
A loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines' insufficient lubrication of the jackscrew assembly. Contributing to the accident were Alaska Airlines' extended lubrication interval and the Federal Aviation Administration's (FAA) approval of that extension, which increased the likelihood that a missed or inadequate lubrication would result in excessive wear of the acme nut threads, and Alaska Airlines' extended end play check interval and the FAA's approval of that extension, which allowed the excessive wear of the acme nut threads to progress to failure without the opportunity for detection. Also contributing to the accident was the absence on the McDonnell Douglas MD-80 of a fail-safe mechanism to prevent the catastrophic effects of total acme nut thread loss.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The Board's full report is available at http://www.ntsb.gov/publictn/publictn.htm.
On January 31, 2000, about 1621 Pacific standard time, Alaska Airlines, Inc., flight 261, a McDonnell Douglas MD-83, N963AS, crashed into the Pacific Ocean about 2.7 miles north of Anacapa Island, California. The 2 pilots, 3 cabin crewmembers, and 83 passengers on board were killed, and the airplane was destroyed by impact forces. Flight 261 was operating as a scheduled international passenger flight under the provisions of 14 Code of Federal Regulations Part 121 from Lic Gustavo Diaz Ordaz International Airport, Puerto Vallarta, Mexico, to Seattle?Tacoma International Airport, Seattle, Washington, with an intermediate stop planned at San Francisco International Airport, San Francisco, California. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
Factual narrative
The Safety Board's full report is available at www.ntsb.gov/publictn/publictn.htm.
On January 31, 2000, about 1621 Pacific standard time, Alaska Airlines, Inc., flight 261, a McDonnell Douglas MD-83 (MD-83), N963AS, crashed into the Pacific Ocean about 2.7 miles north of Anacapa Island, California. The 2 pilots, 3 cabin crewmembers, and 83 passengers on board were killed, and the airplane was destroyed by impact forces. Flight 261 was operating as a scheduled international passenger flight under the provisions of 14 Code of Federal Regulations Part 121 from Lic Gustavo Diaz Ordaz International Airport (PVR), Puerto Vallarta, Mexico, to Seattle?Tacoma International Airport (SEA), Seattle, Washington, with an intermediate stop planned at San Francisco International Airport (SFO), San Francisco, California. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
The accident airplane arrived at PVR about 1239 on the day of the accident. The inbound pilots stated that they met the accident pilots outside the airplane and briefly discussed its status.
Flight data recorder (FDR) information from the accident flight indicated that during taxi for takeoff, when the FDR started recording, the horizontal stabilizer was at the 7° airplane-nose-up position, which was the takeoff pitch trim setting. About 1337, the accident airplane departed PVR as flight 261. A National Transportation Safety Board review of FAA air traffic control (ATC) tapes and FDR data from the accident flight indicated that the first officer was the pilot flying immediately after the airplane's departure. The flight plan indicated that flight 261's cruising altitude would be flight level (FL) 310.
FDR data indicated that during the initial portion of the climb, the horizontal stabilizer moved at the primary trim motor rate of 1/3º per second from 7º to 2º airplane nose up. According to FDR data, the autopilot was engaged at 1340:12, as the airplane climbed through an altitude of approximately 6,200 feet. Thereafter, the FDR recorded horizontal stabilizer movement at the alternate trim motor rate of 1/10º per second from 2° airplane nose up to 0.4° airplane nose down. At 1349:51, as the airplane continued to climb through approximately 23,400 feet at 331 knots indicated airspeed (KIAS), the cockpit voice recorder (CVR) recorded the horizontal stabilizer move from 0.25° to 0.4° airplane nose down. This was the last horizontal stabilizer movement recorded until the airplane's initial dive about 2 hours and 20 minutes later. At 1353:12, when the airplane was climbing through 28,557 feet at 296 KIAS, the autopilot disengaged.
FDR information and airplane performance calculations indicated that, during the next 7 minutes, the airplane continued to climb at a much slower rate. During this part of the ascent, the elevators were deflected between -1° and ?3°, and the airplane was flown manually using up to as much as 50 pounds of control column pulling force. After reaching level flight, the airplane was flown for about 24 minutes using approximately 30 pounds of pulling force at approximately 31,050 feet and 280 KIAS. The airspeed was then increased to 301 KIAS, and the airplane was flown for almost another 1 hour 22 minutes using about 10 pounds of pulling force. At 1546:59, the autopilot was re?engaged.
According to Alaska Airlines documents, ATC and CVR information, and postaccident interviews with Alaska Airlines dispatch and maintenance personnel, the flight crew contacted the airline's dispatch and maintenance control facilities in SEA some time before the beginning of the CVR transcript at 1549:49 to discuss a jammed horizontal stabilizer and a possible diversion to Los Angeles International Airport (LAX), Los Angeles, California. These discussions were conducted on a shared company radio frequency between Alaska Airlines' dispatch and maintenance facilities at SEA and its operations and maintenance facilities at LAX.
At 1549:56, the autopilot was disengaged; it was re-engaged at 1550:15. According to the CVR transcript, at 1550:44, SEA maintenance asked the flight crew, "understand you're requesting…diversion to LA…is there a specific reason you prefer LA over San Francisco?" The captain replied, "well a lotta times its windy and rainy and wet in San Francisco and uh, it seemed to me that a dry runway…where the wind is usually right down the runway seemed a little more reasonable."
At 1552:02, an SEA dispatcher provided the flight crew with the current SFO weather (wind was 180° at 6 knots; visibility was 9 miles). The SEA dispatcher added, "if uh you want to land at LA of course for safety reasons we will do that…we'll…tell you though that if we land in LA…we'll be looking at probably an hour to an hour and a half we have a major flow program going right now." At 1552:41, the captain replied, "I really didn't want to hear about the flow being the reason you're calling us cause I'm concerned about overflying suitable airports." At 1553:28, the captain discussed with the first officer potential landing runways at SFO, stating, "one eight zero at six…so that's runway one six what we need is runway one nine, and they're not landing runway one nine." The first officer replied, "I don't think so." At 1553:46, the captain asked SEA dispatch if they could "get some support" or "any ideas" from an instructor to troubleshoot the problem; he received no response. At 1555:00, the captain commented, "it just blows me away they think we're gonna land, they're gonna fix it, now they're worried about the flow, I'm sorry this airplane's [not] gonna go anywhere for a while…so you know." A flight attendant replied, "so they're trying to put the pressure on you," the captain stated, "well, no, yea."
At 1556:08, the SEA dispatcher informed the flight crew that, according to the SFO automatic terminal information service, the landing runways in use at SFO were 28R and 28L and that "it hasn't rained there in hours so I'm looking at…probably a dry runway." At 1556:26, the captain stated that he was waiting for a requested center of gravity (CG) update (for landing), and then he requested information on wind conditions at LAX. At 1556:50, the SEA dispatcher replied that the wind at LAX was 260° at 9 knots.
Nine seconds later, the captain, comparing SFO and LAX wind conditions, told the SEA dispatcher, "versus a direct crosswind which is effectively no change in groundspeed…I gotta tell you, when I look at it from a safety point I think that something that lowers my groundspeed makes sense." The SEA dispatcher replied, "that'll mean LAX then for you." He then asked the captain to provide LAX operations with the information needed to recompute the airplane's CG because "they can probably whip out that CG for you real quick." At 1558:15, the captain told the SEA dispatcher, "we're goin to LAX we're gonna stay up here and burn a little more gas get all our ducks in a row, and then we'll uh be talking to LAX when we start down to go in there." At 1558:45, the captain asked LAX operations if it could "compute [the airplane's] current CG based on the information we had at takeoff."
At 1602:33, the captain asked LAX operations for wind information at SFO. LAX operations replied that the winds at SFO were 170° at 6 knots. The captain replied, "that's what I needed. We are comin in to see you." At 1603:56, the first officer began giving LAX operations the information it needed to recompute the airplane's CG for landing.
At 1607:54, a mechanic at Alaska Airlines' LAX maintenance facility contacted the flight crew on the company radio frequency and asked, "are you [the] guys with the uh, horizontal [stabilizer] situation?" The captain replied, "affirmative," and the mechanic, referring to the stabilizer's primary trim system, asked, "did you try the suitcase handles and the pickle switches?" At 1608:03, the captai
Aircraft
- Registration
- N963AS
- Reported as
- Douglas MD-83
- Category
- Airplane
- Serial number
- 53077
- Airframe hours
- 26,584
- Engine
- Pratt & Whitney JT8D-217C, turbo fan
- Damage
- Destroyed
- Flight
- Part 121
- Operator
- Alaska Airlines Inc
- Airworthiness certificate
- Standard, Transport; Standard, Normal
- Last inspection
- Continuous airworthiness · January 13, 1999 · 4,177 hours before
- Departed
- PVR · Puerto Vallarta
- Destination
- SFO · San Francisco, CA
- Flight plan
- IFR
- Airport
- LAX · Los Angeles Int'n'l Airport
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew · 2
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 53
- Injuries
- Fatal
- Certificate
- Airline transport
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--w/ waivers/lim
- Last flight review
- November 23, 1999
- Seat
- Left
- Flight hours
- 17,750 total · 14,149 in this make and model · 14,149 as pilot in command · 133 in the last 90 days · 52 in the last 30 days · 3 in the last 24 hours
- Role
- Co-pilot
- Age
- 57
- Injuries
- Fatal
- Certificate
- Airline transport
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Last flight review
- April 25, 1999
- Seat
- Right
- Flight hours
- 8,140 total · 8,060 in this make and model · 142 in the last 90 days · 78 in the last 30 days · 3 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 230° at 8 knots
- Temperature
- 16 °F, dew point 12 °F
- Altimeter
- 30.17 inHg
Docket · 289
The files NTSB released with the investigation on December 14, 2000, on NTSB’s docket system: statements, records, photos and specialists’ reports. 303 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.