Accident Summary
On August 26, 2021, at approximately 1334 eastern daylight time, N413N, an Embraer EMB-505 (Phenom 300), sustained substantial damage during a landing at Elk River Airport (NC06) in Banner Elk, North Carolina. The two pilots were not injured. The flight was conducted as a Title 14 Code of Federal Regulations (CFR) Part 91 repositioning flight operated by Nicholas Services, dba Nicholas Air. The flight originated from Teterboro Airport (TEB), New Jersey, under an instrument flight rules (IFR) flight plan.
NC06 is a private, exclusive-use airport surrounded by mountainous terrain. All flights are restricted to daytime visual flight rules (VFR) operations. The airport's manual advises pilots to carefully read the Elk River Pilot Manual and view the video presentation of arrival and departure procedures.
The pilot-in-command (PIC) and second-in-command (SIC) reported this was their first flight into NC06. They prepared the night before by reviewing landing performance data for dry and wet runways, watching the airport video, and reading the manual. En route, they observed a small rain cell near the airport on weather radar. The SIC contacted airport security and was told the wind was calm with light rain. They planned to divert if unable to make the visual approach.
On approach, the PIC made visual contact with the runway and canceled the IFR flight plan. He began a visual approach to runway 12 using visual cues from the airport video and the precision approach path indicator (PAPI). After touchdown, the PIC applied full brakes, but the airplane did not slow and veered right. It departed the right side of the runway, crossed a small taxiway, and entered grass. The left wing impacted a sign, then a parked sport utility vehicle, which stopped the airplane. Substantial damage occurred to the left wing. The airplane came to rest near the threshold of runway 30, about 20 feet from a cliff.
Airport security video showed the landing roll, with spoilers visible on the left wing. Rain was falling, and water spray trailed the airplane.
Aircraft Information
The accident airplane was equipped with a combination cockpit voice and data recorder (CVDR), which was recovered and sent to the NTSB Recorders Laboratory. The hydraulic brake system delivers pressure based on pedal input. The pilot and copilot brake pedals are mechanically linked, with pedal position transducers sending signals to the brake control unit (BCU), which controls the brake-by-wire system with an antiskid function.
Meteorological Information
NC06 had no weather reporting equipment. At 1350, the nearest station (Watauga County Hospital Heliport, about 12 miles east) reported wind from 190 degrees at 7 knots, visibility 10 miles, temperature 28°C, dewpoint 18°C, and barometric pressure 30.30 inHg. Lightning was observed north and southwest. Multi-radar data estimated a rainfall rate of about 1/2 to 2/3 inch per hour near NC06 at 1348.
Airport Information
NC06 is a non-tower-controlled airport with an elevation of about 3,468 ft. Runway 12/30 is 4,605 ft long and 75 ft wide, asphalt. It has no centerline lights or runway end identifier lights but has a two-light PAPI system on the right side of runway 12. No instrument approaches exist. The visual approach to runway 12 is not straight-in; pilots must fly through a valley and make a left turn on short final.
The Elk River Airport Pilot's Manual warns of significant wind changes over the approach end of runway 12, higher terrain, and recommends a slightly higher approach angle. It emphasizes maintaining strict centerline alignment because of the 75-ft width and surrounding hills and trees. Go-arounds are not recommended due to the significant upslope and higher terrain at the departure end. Landing on runway 30 requires a steeper approach and landing on a downward slope.
Wreckage and Impact Information
The airplane sustained substantial damage to the left-wing attach point link fitting and leading edges of both wings. The BCU was tested and found to have no anomalies that would have precluded normal operation.
Tests and Research
The NTSB conducted a performance study using FDR data, ADS-B data, and aerodynamic information. The study analyzed the approach, landing, and braking performance on a wet runway, referencing the EMB-505 Pilot's Operating Handbook (POH). The POH landing performance criteria include steady 3° approach at Vref, idle thrust at the threshold, maximum braking after touchdown, and operative antiskid.
The study found that during approach, the airplane's flightpath angle averaged about -5°, decreasing to -8° during the left turn. At the threshold (1334:40), airspeed was 118 knots (Vref assumed 110 knots) at 86 ft radio altitude. Wings became level at 1334:41, 54 ft above and 313 ft past the threshold. Touchdown occurred at 1334:47, about 1,410 ft past the threshold, at 111 knots indicated (118 knots true, 121 knots groundspeed), indicating a 3-knot tailwind.
The airplane landed about 9 ft right of centerline and drifted to 29 ft right by 1335:05, 4,292 ft from the threshold and 313 ft from the runway end. Rudder deflected right up to 9.2° at 1335:01, then left to 31.6° at 1335:07, causing heading to decrease from 121° to 71.3° true. Drift angle increased, indicating tires yawed and likely unable to produce much braking force. Oscillations in heading and drift from 1334:53 to 1335:02 suggested aircraft-pilot coupling contributed to directional control difficulties.
FDR data showed the pilot applied brakes after touchdown, with left brake more aggressive initially. Brake pressures peaked 4 seconds after application. From 1334:52 to 1335:01, brake pedals were symmetrical; then right brake was released and left brake deflected for differential braking to yaw left. The airplane crossed into grass at 1335:10 at about 30 knots groundspeed. It came to rest at 1335:16, 4,752 ft past the threshold (147 ft past the runway end) and 147 ft left of centerline.
The performance study determined that the airplane exceeded some POH landing criteria due to the unique approach characteristics at NC06. The maximum wheel braking friction coefficient was significantly less than that implied in POH wet-runway landing distances. If the POH wet-runway braking coefficient had been achieved (with maximum braking maintained from brake application), the airplane would have stopped on the runway with about 290 ft remaining, even with higher-than-nominal airspeed. If it had crossed the threshold at Vref instead of Vref+8 knots, with the same achieved braking coefficient, it would have stopped with about 265 ft remaining. The study noted that friction is shared between braking and cornering; maneuvering for directional control increases stopping distance. The airplane was unable to stop on the paved runway due to the combination of airspeed above Vref, lower-than-assumed runway friction, and cornering forces required for directional control.
Organizational and Management Information
Nicholas Air holds operations specifications for Parts 91 and 135. The General Operations Manual (GOM) does not distinguish between Part 91 and Part 135 flights but states that aircraft repositioning after a revenue flight may be operated under Part 91. The GOM does not specify whether landing weight procedures can be changed for Part 91 flights.
Destination airport runway length requirements for Part 135 are incorporated in the GOM. The accident airplane could only have been dispatched to NC06 with wet conditions under the Destination Airport Analysis Program (DAAP), which allows using 80% of available runway length instead of the 60% required by 14 CFR 135.385(b), but 25% of unfactored dry landing distance must be added for wet conditions.
Section 4.5.3 of the GOM describes steps for landing performance planning using an application by Aircraft Performance Group (APG). Input includes airport, aircraft, systems, landing flap, wind, temperature. For pre-departure planning, zero wind is entered; for inflight, applicable wind component is used. The application provides maximum allowable landing weight from approach climb, field length, and structural limits, for both 60% and 80% factors.
APG provided output for accident conditions: for wet runway, limiting weights were 13,267 pounds (60% factor) and 17,042 pounds (80% factor). The expected landing weight was 15,210 pounds, so only the 80% factor allowed the landing.
The PIC stated he uses the 60% factor for both Part 91 and 135 flights, even though the 80% factor could be used for Part 91. The GOM requires prior permission from the Director of Operations for DAAP use; no evidence of consultation exists.
Nicholas Air's DAAP is regulated by 14 CFR 135.23(r), which requires the GOM to consider airport facilities and topography when establishing safety margins. The GOM does not specifically require that, but the FAA stated it is not an omission because a different section (135.385(b)(2)) assumes landing on the most suitable runway considering wind, ground handling, landing aids, and terrain.
The NTSB learned of another Nicholas Air pilot who made an unsuccessful approach to NC06 11 days earlier. That pilot submitted an SMS report stating that after negotiating terrain on short final, they were 100 ft over the runway and halfway down, so they performed a missed approach and diverted. The pilot opined that the airport should not be used for Part 135 operations. In response, an FAA inspector asked who reviewed the report. The vice president of flight operations stated he reviewed it but was not sure who else, and said the company would not change based on one report.
Additional Information
The accident flight was conducted under Part 91. The corresponding regulation (91.103) requires pilots to become familiar with all available information, including runway lengths at airports of intended use and landing distance information.
On March 11, 2019, the FAA issued Safety Alert for Operators (SAFO) 19001, recommending a conservative approach to landing distance, including using the most adverse braking action report or runway condition code and adding at least 15% safety margin to computed unfactored landing distance when the runway is contaminated or not the same as preflight calculations.
At the calculated landing weight of 15,210 pounds, the unfactored dry landing distance was 2,757 ft. With the 60% factor, minimum runway length would be 4,595 ft. For a wet runway with the 60% factor and an additional 15% safety margin (689 ft), total required runway length would be 5,284 ft. With the 80% factor, the calculated landing distance would be 3,446 ft, and with the 15% safety margin, 4,135 ft.
The NTSB's performance study concluded that the airplane was unable to stop on the paved runway because the combination of airspeed above Vref, lower-than-assumed runway friction, and cornering forces for directional control increased the required stopping distance beyond the available distance.