How did a landing that seemed it would be so right wind up in a go-around that went so wrong? Look at the NTSB’s report on the July 29, 2015, accident involving a Socata TBM 700 at Milwaukee, Wisconsin, in which both occupants were killed, and you’ll see the agency’s take on it. But don’t expect enough to enable you to cope with the same situation should you ever find yourself in the middle of it. We’ll have to fill in the facts with a bit of supposition drawn from our own analysis in order to have a chance of doing that.
The TBM 700 is a complex single-engine airplane if there ever was one. It’s a pressurized turboprop, which can be configured with six or seven seats (the accident airplane had six) and has a maximum takeoff weight of 7,394 pounds. The maximum cruise speed is 300 knots; the typical maximum range is 1,585 nautical miles, and it can have you cruising comfortably at flight level 310. Its dimensions make it appear to be as big as a small house, at a length of 35 feet, wingspan of more than 41 feet and height of just over 14 feet. The accident airplane was imported into the U.S. and issued an FAA standard airworthiness certificate and registration number on December 2, 2009. The corporation in Boston, Massachusetts, that owned it at the time of the accident had purchased it on December 16, 2009.
The airplane had a four-blade, constant-speed, full-feathering propeller. The airplane was approved for flight into known icing conditions, and the maintenance records showed no open discrepancies.
The 53-year-old pilot held an airline transport pilot certificate for multi-engine land airplanes and a single-engine rating limited to operations requiring a commercial certificate or less. He had an instrument rating and was type-rated for Bombardier Challenger and Embraer Phenom 300 airplanes. The TBM 700 did not require a type rating. The pilot’s logbook showed that, as of nine days before the accident, he had logged 1,875 hours with 1,656 as pilot-in-command and 721 hours in TBM 700 airplanes. His third-class medical certificate was current and had no limitations.
The pilot lived in Wenham, Massachusetts, and the airplane was based at the Beverly Municipal Airport (KBVY), also in Massachusetts. Although it’s not mentioned in the NTSB’s narrative on the accident, a document prepared by the Milwaukee County sheriff’s office tells us that an investigator researched the pilot’s actions in the time leading up to the accident flight and also gathered some information from the FBO at KBVY.
According to his widow, the day before the accident, the pilot was at work in his office in Boston, and had a business dinner that evening. He got home at about 10 p.m. eastern daylight time. He had to be up fairly early the next day because of an appointment with his dentist. He went to work, stayed for a few hours, and came home to pick up his daughter. According to the FBO, they arrived at the airport at about 3 p.m. The airplane was topped off with 84 gallons of jet fuel, 42 gallons per wing. The full load would have been approximately 309 gallons. Takeoff from KBVY was at about 3:52 p.m., with a destination of Lawrence J. Timmerman Airport (KMWC) in Milwaukee. Flying distance was 866 nautical miles.
The airplane was on an IFR flight plan, but the weather was quite good. At KMWC, about 25 minutes before the accident, the surface observation was wind 270 degrees at 14 knots, clear sky, 10 miles visibility, temperature 29° C, dew point 6° C, and altimeter 29.93. In the hours preceding the flight’s arrival in the Milwaukee area, it also had been solid VFR, but the wind was gusty, up to 24 knots just two hours before. During the seven hours leading up to the time of the accident, the wind remained pretty much out of the west, varying from 250 degrees to 300 degrees.
The approach controller had cleared the flight for a visual approach to Runway 33R at KMWC. Just before 6:03:52 central time, the pilot was handed off to the Timmerman tower controller and radioed, “Timmerman, TBM 425 kilo juliet inbound runway three three right.” The controller instructed the pilot to “...continue on a visual to three three right, cleared to land.” At 6:04:02, the pilot acknowledged, “Cleared to land, five kilo juliet.”
Just over four minutes went by and, while about 2.5 miles out, the pilot radioed, “Can I get a wind check, please?” At 6:08:18, the controller responded, “Two three zero [at] one zero.” Three seconds later, the pilot radioed, “Three zero one zero, thanks, or two three zero.” The controller confirmed “Two three, two thirty.”
There again was a period silence until 6:09:56, when the pilot radioed, “Go around.” The controller responded, “Five kilo juliet, roger, left closed traffic.”
The tower controller told investigators that because the TBM 700 was the only aircraft he was handling at the time, he was watching the entire approach, go-around and descent. He said he first acquired it visually when it was about 3 miles out. He said that it appeared as if the airplane’s landing gear was fully extended. He said it appeared to be making a normal touchdown in the touchdown zone. He said that he heard a loud squealing noise, which went on for much longer than the typical tire squeal you may hear at touchdown. That’s when the pilot radioed he was going around. The controller said he heard the engine speed accelerate and saw the airplane maintain a level attitude over the runway until it passed Taxiway Charlie intersection. He said he then saw the airplane pitch up and enter a left-climbing turn. Then the airplane appeared to stall, and it descended into terrain in a left-wing-low attitude.
A witness who was walking toward the airport saw the TBM in a steep left bank. He said the landing gear was down but could not be sure about the position of the flaps. He remembers hearing engine noise and noted that, “while [the] bank stayed constant, [the] aircraft ‘slid’ down at a 45-degree angle.” He lost sight of it of because of terrain but heard a crash and saw a fireball.
A witness who was at the kitchen sink of her brother-in-law’s house said she heard a loud engine noise and looked out. She saw an aircraft so low she thought it might hit power lines or the house’s garage. The said the engine was not “sputtering” and there was no smoke. She said she saw a wing strike the ground, then the nose hit and the plane spun around. Then she saw smoke coming out, then flames, and then there was an explosion followed by a second explosion.
Runway 33R was 4,103 feet long by 75 feet wide. Investigators examined numerous slash marks in the surface. They obviously had been created when the propeller of the accident airplane cut into the asphalt. The first slash was measured at 1,384 feet from the runway’s threshold, about 215 feet beyond the end of the touchdown zone. They counted 22 slash marks over a distance of 25 feet and 7 inches. With the landing gear down, the airplane would have had to be in a significant nose low attitude for the prop to have dug in as it did. They did not find evidence that any portion of the airframe impacted the runway.
The main wreckage was located in an open field on the west side of the airport. The propeller assembly and the forward section of the reduction gearbox had separated from the engine. All four propeller blades remained attached to the hub assembly and exhibited S-shaped bends, tip curls, chordwise scratching and leading edge damage. The fractured propeller shaft exhibited features consistent with torsional overload.
The investigation did not categorize the prop damage so we’d know which damage was caused when the propeller was slashing into the runway and which damage was caused as a result of the crash. If it were possible to figure that out, we might have an indication of just how serious the prop damage was when the pilot attempted to climb and maneuver in his go-around. Investigators did determine that the engine was operating at a medium to high power output at the time of impact. It would be interesting to know whether the propeller blades had been in high or low pitch at the time the pilot was attempting to go around. No matter where you have the prop lever set in the cockpit while trying to go around, there are no guarantees those blades haven’t been forced to a different, less-efficient angle as a result of runway impact. If there was significant damage and the prop’s performance was severely degraded but the pilot didn’t know it, his mindset might have been that he had plenty of performance to spare. That might help explain how an experienced ATP wound up not having enough airspeed to avoid a stall during the climbing left turn.
It appeared that the pilot had the airplane properly configured for landing. In addition to the landing gear selector being found in the “down” position, measurements taken of the landing gear actuators were consistent with full extension. The flaps were extended to 34 degrees, according to measurements taken of the flap actuator jackscrews. That’s consistent with what you’d expect during a normal landing.
We do know for a fact that performance can be really bad when you have a damaged prop. A survivor of a prop strike accident told us so. A Cessna 172RG was on an instructional flight out of the Washington Memorial Airport in Marthasville, Missouri, on April 23, 2002. The private pilot was killed, and the instructor received serious injuries. During a touch-and-go, as the plane was in ground effect, the nose suddenly pitched down, and the prop hit the runway. The airplane started vibrating badly, and the flying pilot turned the plane over to the instructor, who was unable to control it. The instructor told investigators that the airplane made a sharp turn to the left and went nose down into the ground.
On May 19, 2016, the propeller of a Beech D35 that was landing struck Runway 10 at the Gatlinburg-Pigeon Forge Airport in Sevierville, Tennessee. A witness said the landing gear had been up and, after the propeller blades struck the runway numerous times, the airplane skidded along until the engine speed increased and the airplane lifted off. The witness said the airplane appeared to be very unstable in ground effect, its performance dramatically deteriorated. It was observed to pitch up, roll to the left, and crash to the ground. The pilot, who was the only occupant, was killed.
About the only thing the NTSB tells us that may indicate all was not benign on board the TBM during its final approach was the pilot asking for a wind check and then making a mistake in reading back the wind direction. Although the airport observations indicate that the wind had calmed down from what it had been earlier, it is possible that the airplane was doing a bit of bouncing around or the pilot was having some difficulty with crosswind correction. However, given his ATP certificate and experience in the TBM 700, that’s hard to fathom. One also has to be skeptical about a sudden gust of wind forcing the nose down and the prop into the asphalt, at least from the information and hourly weather observations we have available.
In fact, the NTSB lays the whole thing squarely at the feet of the pilot. The Safety Board determined that the probable cause of this accident was the pilot’s improper pitch control during the landing, which resulted in the propeller striking the runway, and his failure to maintain adequate airspeed during the subsequent go-around, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall at a low altitude.
I find it interesting that the NTSB didn’t do much with the medical aspects of this investigation. The toxicology report states that the use of the drug ibuprofen by the pilot was detected. It’s a common drug used for pain, fever, muscle aches, headaches and toothaches. Could this have been related to the pilot’s visit to the dentist? Could the pilot have been in pain or discomfort? Or fatigued as a result of the business dinner the night before, and the morning dental visit, and going to the office before the flight? Does that sort of thing make you make a mistake in reading back the wind or predispose you to not recognize when an approach is becoming unstabilized?
Just because the NTSB didn’t provide all of the answers in this investigation doesn’t mean we can’t consider the possibilities on our own. We don’t even need to come up with all of the facts to do something useful for our safety: Just speculating about the possibilities should help us become a bit more defensive and thoughtful about the situations we might face in our own flying. Regardless of what the NTSB did or didn't say in its report, one possibility we might come up with on our own is that if you have a prop strike, the objective should be to get the rest of the airplane on the ground and keep it there.
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, visit www.ntsbreporter.us or write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.