# NTSB ANC08IA026: Beech 1900, N111AX, Aniak, AK, December 17, 2007 - Type: NTSB incident investigation - Classification: Incident · Minor injuries · Incident investigation · Final report - Date: December 17, 2007, 19:40 local (23:40 UTC) - Place: Aniak, AK - Coordinates: 61.5816666666667, -159.543055555556 - Nearby events: https://openairdocs.org/map.md?lat=61.5817&lon=-159.5431&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor, 1 uninjured - Status: Completed, report July 30, 2008 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA-AL-ANC FSDO 03 - NTSB case key (mKey): 67272 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC08IA026 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/67272/pdf - Page: https://openairdocs.org/ntsb/ANC08IA026 ## Probable cause A hazardous leak from carbon dioxide cylinders due to the failure of the flight crew to properly load and secure the cylinders, resulting in crew incapacitation. Factors contributing to the incident were improper hazardous materials procedures used by the shipper, and a failure of the operator to properly train the flight crew in hazardous materials procedures. ## Analysis The flight crew of a cargo airplane had previously loaded a cargo of carbon dioxide cylinders, and then flew to an intermediate airport for fuel. The cylinders had a screw type valve, and a threaded metal safety cap to protect the valve. During the takeoff run after refueling, the crew aborted the takeoff, and taxied back to the airport ramp after hearing a "hissing" sound from the cargo area. Once on the ramp, the captain shut off the engines, but the flight crew lost consciousness before they could exit the airplane. Since the crew filed an IFR flight plan that was not activated, air traffic control personnel contacted the freight office to inquire about the status of the airplane. A freight agent noticed the airplane sitting on the ramp. He opened the door of the airplane, and found the first officer unconscious, inside the door. The captain was unconscious at the controls. He pulled both crewmembers out of the airplane, and ran for help. The flight crew regained consciousness while lying on the ramp, and walked to the freight building. The flight crew were treated at a hospital and released the following day. The first officer reported that as the captain was taxiing back to the airport ramp, he felt the effects of the gas release, and he and the captain opened the cockpit windows. Once stopped, he got up to open the forward door, but collapsed at the door. An FAA inspector examined the airplane, and discovered that the cargo compartment had two tank racks containing five bottles each, standing vertically along each side of the airplane. Two of the cylinders in the left side rack did not have any safety caps installed. Three of the cylinders in the right side rack also did not have any safety caps installed. The caps were found on the floor of the airplane. The inspector found that the middle tank of the three in the right side rack, had a partially open valve. The open tank valve was about 1/2 turn open, and was positioned against the interior side-wall of the cargo compartment. The FAA inspector also indicated that nine carbon dioxide tanks were lying on the floor of the cargo area. They were braced by chocks, but were not strapped down. The crew oxygen masks were not utilized, and the crew oxygen supply tank was full. An FAA Hazardous Materials Division inspector reported that cylinders of carbon dioxide are considered hazardous material because they are pressurized in excess of 40 psi. The inspector noted that the shipper had a responsibility to properly identify and declare hazardous materials that they were shipping, the carrier had a responsibility to properly train airplane crewmembers to identify and accept hazardous materials, and the flight crew had a responsibility to properly secure hazardous materials during transport. ## Factual narrative On December 17, 2007, about 1940 Alaska Standard time, the crewmembers of a Beech 1900 airplane, N111AX, aborted their takeoff from Aniak, Alaska, and taxied back to the airport ramp, when they heard a "hissing" sound from the cargo area. Once on the ramp, the captain shut off the engines. The captain and first officer lost consciousness before they could exit the airplane. The airplane was being operated as an instrument flight rules (IFR) cross-country nonscheduled cargo flight under Title 14, CFR Part 135, when the incident occurred. The airplane was operated as Flight 81, by Alaska Central Express, Anchorage, Alaska, and was not damaged. The airline transport certificated pilot was not injured. The airline transport certificated first officer received minor injuries. Visual meteorological conditions prevailed, and an IFR flight plan was filed from Aniak, to Anchorage, but was not activated. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on December 17, the director of operations for the operator reported that he received a call from a ramp agent at Inland Aviation, Aniak. Inland Aviation personnel provided ground handling and fueling for the flight. The agent reported that after the airplane left the ramp, he paid no further attention to it until he received a telephone call from Anchorage Air Traffic Control Center (ARTCC) personnel. ARTCC was inquiring about the airplane, as the crew had not radioed that they were airborne. The agent looked out of the freight building and noticed the airplane sitting on the ramp. The engines were stopped, and the airplane lights were "on" but dim. He opened the door of the airplane, and found the first officer unconscious, inside the door. The captain was unconscious at the controls. He pulled both crewmembers out of the airplane, onto the ramp, and then ran to call for help. The flight crew regained consciousness while lying on the ramp, and then walked to the freight building. Medical personnel provided care, to include 100 percent oxygen. The flight crew were flown to a hospital in Anchorage where they were released the following day. The crewmembers had no memory of events from the time they stopped the airplane on the ramp, until they woke-up on the airport ramp. The first officer reported that as the captain was taxiing back to the airport ramp, he felt the effects of the gas release, and both crewmembers opened the cockpit windows. Once stopped, he got up to open the forward door, but collapsed at the door. The director of operations indicated that the airplane initially departed Sheldon Point, Alaska, with an intermediate stop in Aniak for fuel and cargo, before continuing to Anchorage. At Sheldon Point, the crew loaded several large metal cylinders designed to hold compressed gas. Several of the cylinders were empty, but several were full of carbon dioxide. The cylinders have a screw type valve, and a threaded metal safety cap, which is used to protect the valve. Several cylinders were placed in metal racks along the left and right sides of the airplane's cargo compartment. Several others were placed on the floor. On December 18, a Federal Aviation Administration (FAA) inspector, Anchorage Flight Standards District Office (FSDO), inspected the airplane in Aniak. He reported that the cargo compartment had two tank racks containing five bottles each, standing vertically along each side of the airplane. Two of the cylinders in the left side rack did not have any safety caps installed. Three of the cylinders in the right side rack also did not have any safety caps installed. The caps were found on the floor of the airplane. The inspector found that the middle tank of the three in the right side rack, had a partially open valve. The interior of the airplane had a large amount of frost. The open tank valve was about 1/2 turn open, and was positioned against the interior side-wall of the cargo compartment. The FAA inspector also indicated that nine carbon dioxide tanks were lying on the floor of the cargo area. They were braced by chocks, but were not strapped down. The crew oxygen masks were not utilized, and the crew oxygen supply tank was full. An FAA Hazardous Materials Division inspector reported that the cylinders of carbon dioxide are considered hazardous material because they are a pressurized gas in excess of 40 psi. The inspector also indicated that the shipper has a responsibility to properly identify and declare hazardous materials that they are shipping, the carrier has a responsibility to properly train airplane crewmembers to identify and accept hazardous materials, and the flight crew has a responsibility to properly secure hazardous materials during transport. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hazardous materials leak/spill, takeoff - roll/run - procedure inadequate, other person (contributing factor) - loading of cargo - improper, flightcrew (cause) - inadequate training, company/operator management (contributing factor) - Miscellaneous/other, standing - engine(s) not operating - incapacitation(loss of consciousness), flightcrew - oxygen system,crew - not activated ## Aircraft - Registration: [N111AX](https://openairdocs.org/aircraft/N111AX), registered now, S/N UC-81, built 1989 (OpenAirDocs) - Reported make and model: Beech 1900 - Registry model: [Beech 1900C](https://openairdocs.org/model/beech-1900c) (registry code 1154161) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-60A](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-60a) (registry code 52043, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: UC-81 - Airframe hours: 48506 - Engines: Pratt & Whitney Canada PT6A-65B 1100 horsepower turbo prop - Damage: No damage - Flight: Part 135 - Registered owner: Alaska Central Express - Airworthiness certificate: Standard, Normal - Last inspection: Continuous airworthiness, December 1, 2007, 96 hours before - Departed: PANI, Aniak, AK - Destination: PANC, Anchorage, AK - Flight plan: IFR - Airport: PANI, Aniak ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: none; airline transport, flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review September 1, 2007; seat: left; flight hours: 19,100 total, 8,000 in this make and model - Co-pilot; age 30; injuries: minor; airline transport, flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 1, 2007; seat: rear; flight hours: 4,700 total, 600 in this make and model, 280 as pilot in command ## Weather - Conditions: Visual (VMC), Night/dark - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: -6 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20071217828769I](https://openairdocs.org/incident/20071217828769I), Dec 17, 2007: Beech 1900C, Aniak, AK, No damage. (-23) On taxi for takeoff aircrew heard a loud hissing sound from aft section of the aircraft. Aircrew taxied back to ramp area. PIC became incapacitated. SIC… ## Other investigations on N111AX (2) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC12CA042](https://openairdocs.org/ntsb/ANC12CA042), May 24, 2012: Beech 1900C (N111AX), McGrath, AK, substantial damage. Probable cause: The pilot's unstable approach and overrotation, which resulted in a tailstrike. - [NTSB ANC11LA004](https://openairdocs.org/ntsb/ANC11LA004), Oct 18, 2010: Beech 1900C (N111AX), Sitka, AK, substantial damage. Probable cause: A lightning strike which resulted in substantial damage to the elevator. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.