NTSB Factual Report

HISTORY OF FLIGHT

On March 8, 2013, about 0815 Alaska standard time, a Beech 1900C airplane, N116AX, operating as Alaska Central Express flight 51, was destroyed when it collided with rising terrain about 10 miles east of Aleknagik, Alaska. The captain and first officer were fatally injured. Flight 51 was a cargo flight operating under the provisions of 14 Code of Federal Regulations (CFR) Part 135. Instrument meteorological conditions (IMC) prevailed along the route of flight, and the airplane was operating on an instrument flight rules (IFR) flight plan. The flight departed King Salmon Airport, King Salmon, Alaska, about 0750, and was en route to Dillingham Airport (DLG), Dillingham, Alaska.

A postaccident review of Federal Aviation Administration (FAA) radar data and radio communication recordings revealed that, about 0803, the pilot requested the RNAV/GPS runway 19 approach to DLG and asked for routing directly to ZEDAG, the initial approach fix (IAF). At the time of the pilot's request, the airplane was about 30 miles southeast of ZEDAG at an altitude of about 5,900 feet mean sea level (msl). The on-duty Anchorage Air Route Traffic Control Center (ARTCC) radar controller cleared the airplane to fly directly to ZEDAG followed by the ZEDAG transition and the RNAV/GPS runway 19 approach. The controller told the pilot to maintain an altitude "at or above 2,000 feet msl until established on a published segment of the approach." The pilot read back, "Maintain two thousand until a published segment of the approach." About 6 minutes later, as the airplane descended toward the IAF, the pilot requested to enter the holding pattern while checking on runway conditions on another radio frequency, and the controller granted the request. At the time of the pilot's request, the airplane was at an altitude of about 2,200 feet msl. The airplane subsequently disappeared from the controller's radar display, and all contact with the flight was lost.

At 0830, the on-duty ARTCC operations manager notified the Anchorage rescue coordination center (RCC) of the missing airplane, and, at 0835, the FAA issued an alert notice. About 0854, a 406-MHz beacon activation notification was received by the RCC, and search and rescue operations were initiated. Initial attempts to reach the accident site were hampered by poor weather conditions.

On March 9, about 0606, aerial searchers located the accident site about 6 miles north-northwest of ZEDAG in an area of steep, snow and ice-covered terrain known as "the Muklung Hills." About 0703, a ground search party reached the accident site, which was at an elevation of about 1,996 feet msl.

FLIGHT CREW INFORMATION

Captain

The captain, age 38, held an airline transport pilot certificate with an airplane multiengine land rating and commercial pilot privileges with an airplane single-engine land rating and a type rating in the Beech 1900. His most recent first-class FAA medical certificate was issued June 11, 2012, with no limitations.

The captain was hired by Alaska Central Express on July 18, 2008, and, at that time, he had 260 hours of total flight experience. He completed his initial company training, including Beech 1900 second-in-command (SIC) ground training, on July 28, 2008, and was assigned to fly as SIC of Beech 1900 airplanes at the company's base in Anchorage. On September 7, 2011, he was upgraded to a Beech 1900 captain. The operator reported that the captain had accumulated 5,770 total flight hours, including 5,470 hours in the accident airplane make and model. His most recent airman competency/proficiency check, which was administered by a company check airman, was completed on October 20, 2012.

On March 5, the captain's duty day started at 0330 and ended at 1130, and he flew 4.4 hours. On March 6, his duty day started at 0330 and ended at 1300, and he flew 4.5 hours. On March 7, his duty day started at 0430 and ended at 1000, and he flew 3.3 hours. On March 8, the day of the accident, his duty day started at 0430, and he flew 1.6 hours before the accident.

First Officer

The first officer, age 21, held a commercial pilot certificate with airplane single-engine land, multiengine land, and instrument airplane ratings. His most recent FAA second-class medical certificate was issued August 9, 2012, with no limitations.

The first officer was hired by Alaska Central Express on November 12, 2012, and, at that time, he had 220 hours of total flight experience. He completed his initial company training, including Beech 1900 SIC ground and flight training, on November 30, 2012, and was assigned to fly as SIC of Beech 1900 airplanes at the company's base in Anchorage. The operator reported that the first officer had accumulated 470 total flight hours, including 250 hours in the accident airplane make and model. His most recent airman competency/proficiency check, which was administered by a company check airman, was completed on December 1, 2012.

On March 5, the first officer's duty day started at 1100 and ended at 2200, and he flew 7.4 hours. On March 6, his duty day started at 1200 and ended at 1930, and he flew 4.2 hours. On March 7, he was off duty. On March 8, the day of the accident, his duty day started at 0430, and he flew 1.6 hours before the accident.

AIRCRAFT INFORMATION

The airplane, manufactured in 1992, was a twin-engine Beech 1900C equipped with retractable landing gear, two Pratt and Whitney PT6A-65B engines, and controllable-pitch propellers. Alaska Central Express maintained the airplane in accordance with an approved continuing airworthiness program, and the most recent required inspection was completed on March 7, 2013, when the airplane had accumulated 29,824 total hours.

The airplane was equipped with a Bendix/King KMD 850 multifunction display capable of providing audible and visual terrain warnings. The airplane was also equipped with dual Garmin 430W units capable of providing visual terrain warnings. Both warnings could be inhibited by the flight crew.

The airplane was equipped for instrument flight into icing conditions and could be operated by a single pilot. The airplane was not equipped with, nor was it required to be equipped with, a cockpit voice recorder or a flight data recorder.

WRECKAGE AND IMPACT INFORMATION

The airplane's wreckage was located in an area of steep, ice and snow-covered terrain on a southeast-facing slope. The terrain was rough and uneven, and high-wind conditions after the accident had created areas of drifted snow, moved lighter pieces of debris, and buried some debris. The initial impact point was at an elevation of about 1,996 feet, and the debris path extended about 900 feet uphill to an elevation of about 2,300 feet in a triangular/fan shape. About 700 feet from the initial point of impact, the major debris field was more than 400 feet wide, and single pieces of debris could be seen at greater distances in all directions. The debris path was on a magnetic heading of about 340 degrees. According to topographic maps, the peak elevation is 2,550 feet. The initial impact point was a rock outcrop protruding from the snow. Metal scrapings were found on the rock surface consistent with damage observed on the center of the airplane's fuselage. No indications of any wing impact were found near the initial impact point. The first structural piece was located about 400 feet from the initial impact point. Large sections of fuselage and expelled cargo were located about 525 feet from the initial impact point. The fuselage and cockpit were found separated into three large pieces.

Subsequent examination of the engines and propellers indicated that the propeller blades had all sheared off at the propeller hub, and the engines' exhausts exhibited signs of hot metal folding.

Damage to the Bendix/King KMD 850 and dual Garmin 430W units precluded testing, and the preaccident configuration of the units (including which functions were enabled or inhibited by the flight crew) could not be determined.

MEDICAL AND PATHOLOGICAL INFORMATION

Captain

A postmortem examination of the captain was performed under the authority of the Alaska State Medical Examiner in Anchorage on March 11, 2013. The cause of death was reported as multiple blunt force injuries sustained in an airplane crash, and the manner of death was an accident. However, the autopsy identified severe coronary artery disease with greater than 85% stenotic lesion in the distal left anterior descending artery. Nevertheless, there was no suggestion of medical impairment or incapacitation related to the probable cause of the accident.

A toxicological examination by the FAA's Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma, on April 30, 2013, revealed dextrorphan and doxylamine in urine and 0.016 ug/ml doxylamine in blood.

According to CAMI doxylamine is a sedating antihistamine available over the counter and by prescriptions and used to treat cold and allergy symptoms. Its therapeutic window is 0.050 to 0.150 ug/ml and it carries the following warning: "May impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery)." The absence of dextromethorphan or its metabolite in the blood suggests the cough suppressant was no longer having any effect on the captain.

Given that the toxicology testing identified a level well below the therapeutic window, there is no evidence that it was impairing the captain at the time of the accident.

First Officer

A postmortem examination of the first officer was performed under the authority of the Alaska State Medical Examiner in Anchorage on March 11, 2013. The cause of death was reported as multiple blunt force injuries sustained in an airplane crash. The manner of death was an accident.

A toxicological examination by CAMI on April 18, 2013, was negative for any alcohol or drugs.

METEOROLOGICAL INFORMATION

The DLG weather observation at 0745 reported cloud ceiling 1,500 feet overcast, wind from 100 degrees at 17 knots gusting to 30 knots, 7 miles visibility in light rain, temperature of 34 degrees F, dew point temperature of 32 degrees F, and an atmospheric pressure of 29.09 inches of mercury. IMC prevailed along the route of flight and in the holding pattern area for the DLG RNAV/GPS runway 19 approach.

AIR TRAFFIC CONTROL

DLG is southwest of the ZEDAG IAF, and the published DLG RNAV/GPS runway 19 instrument approach procedure indicates that the terminal arrival area (TAA) minimum altitude when approaching ZEDAG from the southeast (the direction from which the accident flight approached) is 5,400 feet msl within 30 nautical miles of ZEDAG.

One of three peaks in the Muklung Hills with an elevation of 2,550 feet is located about 6 miles north-northwest of ZEDAG. The published minimum safe altitude while flying in the holding pattern is 4,300 feet msl.

An annotated copy of the RNAV/GPS runway 19 instrument approach procedure and diagrams showing the airplane's route of flight are contained in the public docket for this report.

The following is an excerpt from the FAA Anchorage ARTCC transcript of the radio communications between the flight crew (call sign AER51) and the ARTCC specialist, beginning at 0803:33, when the flight crew requested an approach clearance to DLG and of a call between the ARTCC specialist and the DLG flight service station (FSS), which took place between 0804:19 and 0804:36:

0803:33 AER51: Anchorage Center Ace Air fifty one current weather down into

Dillingham requesting RNAV one nine approach any chance we can get direct

ZEDAG?

ARTCC: Ace Air fifty one cleared direct to the Dillingham Airport via direct

ZEDAG ZEDAG transition. Maintain ah maintain at or above two thousand until

established on a published segment of the approach. Cleared RNAV runway one

niner approach to Dillingham Airport. Remain this frequency.

AER51: We'll stay with you. Cleared to ZEDAG transition for RNAV one nine

approach into Dillingham. Maintain [ARTCC controller dialing the DLG

FSS] two thousand until a published segment of the approach Ace Air fifty one.

0804:18 ARTCC: Is Ace Air fifty one Beech nineteen hundred Dillingham one

seven two zero RNAV one nine.

0809:31 AER51: Anchorage Center Ace Air fifty one [we're] approaching ZEDAG we'd

like to hold waiting for more information if possible.

ARTCC: Ace Air fifty one say again?

AER51: Ace Air fifty one requesting hold at ZEDAG for runway conditions.

ARTCC: Ace Air fifty one hold north of ZEDAG as published expect further

clearance one eight zero zero upon your request.

AER51: Hold north of ZEDAG expect further clearance one eight zero zero.

We're still checking on runway conditions Ace Air fifty one thanks.

ARTCC: Ace Air fifty one roger.

0814:25 Dillingham FSS: Dillingham Radio reference Ace Air fifty one

ARTCC: Yeah

Dillingham FSS: Ah he said he was going to hold ah and wait for an update

on the runway conditions. I'm trying to get a hold of him. I've got an update on

the runway…been trying to get a hold of him.

ARTCC: Do you want me to relay to em?

Dillingham Airport FSS: Ah yeah we're just showing patchy thin water on

the runway now.

ARTCC: Okay I'll let him know. Thanks.

Dillingham Airport FSS: Alright thank you.

0814:50 ARTCC: Ace Air fifty one you up?

The flight's last radio transmission was made at 0809:51. During postaccident interviews, the controller who handled the flight stated that he did not expect the airplane to descend below 5,400 feet and that he did not notice when it did so. He stated that he did not notice the airplane's actual altitude when the pilot requested holding at ZEDAG. He stated that, when he cleared the pilot to hold at ZEDAG "as published," he expected the pilot to climb the airplane to 4,300 feet msl as shown in the profile view of the approach procedure.

Air traffic control (ATC) recorded automation data showed that the airplane's trajectory generated aural and visual minimum safe altitude warnings (MSAW) on the controller's radar display, which included a 1-second aural alarm at 0809:16 and a flashing "MSAW" indication in the airplane's data block that continued from 0809:16 until the end of the flight. The controller said that he was not consciously aware of any such warnings from his display. The controller did not issue any terrain conflict alerts or climb instructions to the flight crew. A complete ATC transcript and the ATC Group Chairman Factual Report are contained in the public docket for this report.

OPERATOR INFORMATION

Alaska Central Express is a 14 CFR Part 135 air carrier and holds on-demand and commuter operations specifications. The company headquarters is located at the Ted Stevens Anchorage International Airport, Anchorage, Alaska, and serves various communities throughout the Aleutian Islands and western, southwestern, and southeast Alaska.

Company policy requires flight crews to use approved checklists during all phases of flight. The Alaska Central Express BE-1900/1900C Normal Checklist includes a descent and approach checklist that specifies that the flight crew complete a briefing for the approach to be conducted. A typical instrument approach briefing includes, in part, referencing the published approach information and verbally verifying the navigation frequencies to be used, the headings to be flown, and the minimum safe altitudes for the various segments of the approach. The normal checklist also includes a prestart checklist that specifies a circuit breakers check/test to ensure power to all instruments and avionics. The after-start checklist requires an electrical system check, the post

NTSB Probable Cause

The flight crew's failure to maintain terrain clearance, which resulted in controlled flight into terrain in instrument meteorological conditions. Contributing to the accident were the flight crew's failure to correctly read back and interpret clearance altitudes issued by the air traffic controller, their failure to adhere to minimum altitudes depicted on the published instrument approach chart, and their failure to adhere to company checklists.

Also contributing to the accident were the air traffic controller's issuance of an ambiguous clearance to the flight crew, which resulted in the airplane's premature descent, his failure to address the pilot's incorrect read back of the assigned clearance altitudes, and his failure to monitor the flight and address the altitude violations and issue terrain-based safety alerts.