The NTSB has released its final report on the October 25, 2002, accident in which U.S. Senator Paul Wellstone of Minnesota and seven others were killed at Eveleth, Minn. The twin-engine turboprop King Air A100 didn’t have a cockpit voice recorder, so there was no possibility of investigators learning what the pilot and copilot might have said to each other about the way things were progressing during the VOR approach to Eveleth. Investigators had to rely on other things to figure out what caused the airplane to experience an aerodynamic stall at a critically low altitude. In reconstructing the accident scenario, investigators used radar data, ATC audiotapes, aircraft performance numbers, interviews and a large body of experience derived from investigating other accidents.
Investigators found that the flight crew failed to recognize two things that should’ve prompted an immediate go-around during the VOR approach to runway 27 into Eveleth-Virginia Municipal Airport (EVM): low airspeed and full needle deflection on the CDI. The flight crew should’ve been flying at no less than 120 knots. The airplane operator’s procedures called for a non-precision approach to be abandoned if the airspeed deviated by more than 10 knots below 500 feet AGL. The airspeed remained below the required speed for about 50 seconds, reaching a low of about 76 knots. Procedures also called for an approach to be abandoned with a CDI deflection of more than three-quarters scale.
According to FAA records, the pilot called the Princeton Automated Flight Service Station (AFSS) for an abbreviated weather briefing for the flight from St. Paul Downtown Airport (STP) at St. Paul, Minn., to Eveleth at about 7:16 on the morning of the accident. The AFSS specialist informed the pilot that AIRMETs for IFR and icing conditions were current over the entire route. He also stated that cloud conditions at EVM were reported as scattered at 1,000 feet and overcast at 2,000 feet, and that visibility was reported as four statute miles in light snow. He added that between STP and EVM, the cloud ceilings were reported between 300 and 600 feet, and visibility was one to four statute miles in light snow and mist.
The pilot then asked for freezing level information and weather information for Duluth (DLH), Minn., in case he had to land there as an alternate to EVM. The AFSS specialist indicated that at that time, DLH was reporting an overcast cloud ceiling of 500 feet and visibility of two statute miles in light snow and mist. He added that the terminal forecast indicated an overcast cloud ceiling of 500 to 900 feet and visibility of one to three statute miles in rain or snow. At about 7:19 a.m., the pilot stated, “You know what? I don’t think I’m going to take this flight.”
According to Senator Wellstone’s campaign scheduler, the pilot contacted her at about 7:20 a.m. and informed her that they might experience icing conditions during the flight. When she asked the pilot what he’d do if icing became a problem, he told her that the airplane was equipped with de-icing equipment and, if necessary, that he could turn back toward warmer air to melt the ice or divert to Duluth. She said that the pilot did not indicate that he was thinking of canceling the flight.
At about 7:30, the pilot contacted the Part-135 charter company’s headquarters and asked the receptionist to inform the company’s scheduling office that the senator’s flight would be delayed because of the weather.
The pilot then contacted the FBO at STP and advised them that he’d be departing at about 1 p.m., instead of 9:20 a.m., and asked to be sure that the airplane would be available at that time. But when the senator’s campaign scheduler talked to the pilot again at about 8:00, they agreed to go ahead with the flight as originally scheduled.
According to FAA records, at about 8:18, the pilot contacted the Princeton AFSS for a weather update. He learned that the AIRMETs for IFR and icing conditions were still current. The pilot filed an IFR flight plan.
The copilot was first to arrive at the FBO. He went to the hangar to get catering items for the flight and to preflight the airplane. The accident pilot arrived at STP shortly before 9:00. By that time, the senator and his staff were already at the airport.
According to FAA Air Traffic Control (ATC) records, the flight departed STP at about 9:37 and was cleared to proceed directly to EVM at 13,000 feet.
About 10:01, the copilot contacted Duluth Approach Control and reported level at 13,000 feet proceeding direct to EVM. The controller responded, “King Air four-one-bravo-echo Duluth approach, when you have Eveleth weather, advise what approach you [would] like…the last report was from a Saab descended into Duluth…had light rime ice but earlier, just about an hour ago, a DC-9 had moderate rime between niner-thousand and one-one-thousand.”
The copilot acknowledged the transmission. About 10:02, the controller radioed to descend to and maintain 4,000 feet at the pilot’s discretion.
About 10:04, the copilot radioed that he had the current EVM weather and that he’d like the VOR runway 27 approach. The controller advised, “Expect vectors for the approach.”
The copilot acknowledged the transmission. About 10:06, the controller asked the flight crew what they intended to do in the event of a missed approach.
The pilot responded, “Well, let’s hope we don’t have that. If we do have a missed approach, we’ll go up and circle and figure this out; I’ll hold at the VOR.”
About 10:09, the copilot reported leaving 13,000 feet for 4,000 feet. Radar data indicated that the airplane was approximately 34 miles south of EVM at this time. At about 10:12, the controller instructed the flight crew to descend to 3,500 feet at the pilot’s discretion. The VOR runway 27 approach procedure prescribes 2,800 feet as the initial approach altitude, but the controller said that he assigned an initial approach altitude of 3,500 feet to ensure that he didn’t lose radar contact with the accident airplane.
By 10:17:35, the airplane had leveled off at 3,500 feet and was on a 360-degree assigned heading with the airspeed decreasing through about 190 knots calibrated airspeed (KCAS).
At 10:18:13, when the airplane was less than a 1⁄2-mile south of the published VOR runway 27 approach course, the controller advised, “One-zero miles from the VOR, turn left heading three-zero-zero. Maintain three-thousand-five-hundred ’til established on the final approach course cleared for the VOR runway two-seven approach Eveleth.”
The copilot acknowledged the instruction. Radar data indicate that the airplane began turning left while maintaining 3,500 feet and slowing through about 164 KCAS. Almost immediately after the airplane began its left turn, it overshot the approach course and traveled for almost one mile north of the course as it continued the turn until it established a ground track of about 262 degrees.
At 10:19:12, the controller stated, “King Air one-bravo-echo, change to advisory frequency approved; advise cancellation of IFR with the Princeton flight service when on the ground.” The copilot acknowledged the instruction. The airplane began its descent from 3,500 feet. The decrease in airspeed stopped at about 155 KCAS and increased to about 170 KCAS. Vertical speed increased through 1,000 feet per minute (fpm) as the airplane descended through 3,200 feet. The airspeed stabilized briefly at about 170 KCAS and the vertical speed peaked at about 1,400 fpm.
At 10:20:06, as the airplane passed through the approach course about five miles east of the runway 27 threshold, a slight right turn was initiated and the airplane’s airspeed and vertical speed decreased. The airplane established a ground track of about 269 degrees and maintained this track until the end of the radar data at 10:21:42.
The last two radar returns indicated that the airplane had slowed to about 76 KCAS at 1,800 feet. One witness saw the airplane to the west of his location (approximately 4 1⁄2 miles east of the runway 27 threshold) “just beneath a low layer of clouds” and that “the top of the airplane may still have been in the clouds.” He stated that he noticed the landing gear was down, but that he couldn’t remember if any lights were illuminated on the airplane. The airplane impacted the ground about 1.8 miles southeast of the approach end of runway 27. The wreckage location was about 1⁄4-mile south-southwest of the last radar return. Investigators and inspection flights by the FAA found slight misalignment and “bends” of signals from the Eveleth VOR. However, the Safety Board determined that these discrepancies wouldn’t have contributed to the accident. The Safety Board also found that icing was not a factor in the accident based, in part, on interviews with pilots who had been flying in the area.
The NTSB determined the probable cause of this accident was the flight crew’s failure to maintain adequate airspeed, which led to an aerodynamic stall from which they didn’t recover.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.