Home » ASN News
Limitations of see-and-avoid, lack of warning alerts, led to Alaska midair collision
21 April 2021

Limitations of see-and-avoid, lack of warning alerts, led to Alaska midair collision

A midair collision of two air tour airplanes was caused by “the inherent limitations of the see-and-avoid concept” along with the absence of alerts from both airplanes’ traffic display systems, the NTSB concluded.

The two airplanes, a float-equipped DHC-2 Beaver operated by Mountain Air Service and a float-equipped DHC-3 Otter operated by Taquan Air, collided at an altitude of 3,350 feet about eight miles northeast of Ketchikan, Alaska, May 13, 2019. The DHC-2 pilot and four passengers died; the DHC-3 pilot suffered minor injuries, nine passengers were seriously injured, and one passenger died.

Ketchikan graphic 14APR21.jpg

Investigators determined that the pilot of the DHC-2 would not have had the opportunity to see and avoid the DHC-3 because his view was obscured by the cockpit structure, right wing and a passenger in the copilot’s seat. The lack of apparent motion of the DHC-2 when viewed from the DHC-3, and the obscuration of the DHC-2 by the window post for 11 seconds before the collision, made it difficult for the DHC-3 pilot to see the DHC-2 airplane.

Both airplanes’ traffic display systems were equipped with ADS-B Out and In.
Although the traffic display system installed on the DHC-3 depicted aircraft in the area, it could not provide aural or visual alerts to warn of a potential collision. The pilot of the DHC-3 last recalled looking at his traffic display about four minutes before the accident and did not identify any collision threats. A traffic alerting feature previously available in the DHC-3 was disabled by a 2015 equipment upgrade.

Unlike the DHC-3, the pilot of the DHC-2 airplane had access to a traffic display system that could provide aural and visual alerts, but the DHC-2 pilot would not have received any such alerts because the DHC-3 airplane was not broadcasting required altitude information.

Requiring all Part 135 operators, as well as all air tour operators in high-traffic areas, to be equipped with collision avoidance technology that provides visual and aural alerts, were two of the five new recommendations made to the FAA. The NTSB also reiterated a safety recommendation to the FAA for the sixth time in five years. That recommendation asked the agency to require all Part 135 operators to establish safety management systems. 

Loadsheet error factor in A320 tailstrike incident, Milan

Checklist interruption factor in Metroliner runway excursion, Canada

Pilot’s actions, maintenance issues contributed to fatal crash of historic B-17 airplane

The National Transportation Safety Board detailed in an accident report issued April 13 the circumstances that led to the crash of a Boeing B-17G airplane that killed seven people and injured seven others.

The NTSB determined the probable cause of the accident was the pilot’s failure to properly manage the airplane’s configuration and airspeed following a loss of engine power.

The Word War II-era Boeing B-17G airplane had just departed Bradley International Airport in Windsor Locks, Connecticut, Oct. 2, 2019, on a “living history flight experience” flight with 10 passengers when the pilot radioed controllers that the airplane was returning to the field because of an engine problem.  The airplane struck approach lights, contacted the ground before reaching the runway and collided with unoccupied airport vehicles; the majority of the fuselage was consumed by a post-crash fire.

Windsor Locks.jpg

Flightpath data indicated that during the return to the airport the landing gear was extended prematurely, adding drag to an airplane that had lost some engine power. An NTSB airplane performance study showed the B-17 could likely have overflown the approach lights and landed on the runway had the pilot kept the landing gear retracted and accelerated to 120 mph until it was evident the airplane would reach the runway.

The pilot also served as the director of maintenance for the Collings Foundation, which operated the airplane, and was responsible for the airplane’s maintenance while it was on tour in the United States. Investigators said the partial loss of power in two of the four engines was due to the pilot’s inadequate maintenance, which contributed to the cause of the accident.

The NTSB also determined that although the Collings Foundation had a voluntary safety management system in place, it was ineffective and failed to identify and mitigate numerous hazards, including the safety issues related to the pilot’s inadequate maintenance of the airplane.

The Federal Aviation Administration’s oversight of the Collings Foundation safety management system was also ineffective, the NTSB said, and cited both as contributing to the accident.

The NTSB recommended the FAA require safety management systems for the certain revenue passenger-carrying operations which included living history flight experience flights such as the B-17 flight.

The NTSB also issued recommendations to the FAA that would enhance the safety of revenue passenger-carrying operations conducted under Part 91, including those conducted with a living history flight experience exemption, which currently allows sightseeing tours aboard former military aircraft to be operated under less stringent safety standards than other commercial operations.

Report: Crew missed SIGMETs, factor in B757 low fuel emergency at Manchester

Iran issues final report on Ukraine International flight PS752 shoot down

Report: Utair Boeing 737-500 landed short and hit snow bank at Usinsk, Russia

Continued flight in poor weather led to 2019 Cessna Caravan floatplane crash in Canada

In its investigation report released today, the Transportation Safety Board of Canada (TSB) found that the decision to continue flying in poor weather led to the fatal July 2019 controlled flight into terrain occurrence on Addenbroke Island, British Columbia (BC).

On 26 July 2019, at around 9:30 local time, a float-equipped Cessna 208 Caravan aircraft, operated by Seair Seaplanes, departed Vancouver International Water Aerodrome, BC, for a visual flight rules (VFR) flight to a fishing lodge near Port Hardy, BC, with one pilot and eight passengers on board. At 11:04 local time, the aircraft struck the hillside of Addenbroke Island, 9.7 nautical miles from the destination. The pilot and three of the passengers were fatally injured. Four of the surviving passengers received serious injuries, and one received minor injuries. The aircraft was destroyed.

The investigation found that the flight departed the Vancouver International Water Aerodrome despite reported and forecasted weather conditions that were below VFR requirements near the destination, and that the decision to depart may have been influenced by group dynamics. After encountering poor weather conditions, the pilot continued the flight in reduced visibility, without recognizing the proximity to terrain, and subsequently impacted the rising terrain of Addenbroke Island.

Although the aircraft was equipped with advanced avionics devices (G1000), they were configured in a way that made the system ineffective at alerting the pilot to the rising terrain ahead. Additionally, the pilot’s attention, vigilance and general cognitive function were likely influenced to some degree by fatigue. Although the aircraft was equipped to capture flight data, Seair had not established a flight data monitoring (FDM) program, nor was it required to by regulation.

However, air operators are not alone in monitoring for safe operations. Following this occurrence, Transport Canada (TC) did not conduct any reactive surveillance, initiate new surveillance activities, escalate upcoming surveillance activities, or conduct targeted or compliance inspections. If TC does not apply sufficient oversight of operators, there is a risk that air operators will be non-compliant with regulations or drift toward unsafe practices, thereby reducing safety margins.

Following the occurrence, Seair contracted an aviation consulting company to conduct an operational and maintenance review, updated its standard operating procedures to highlight the limitations of the autopilot system, and added an acceptable use policy on personal electronic devices in the cockpit.

Report: Peruvian Boeing 737-300 veered off runway after unstable approach in storm

Incorrect crosswind technique factor in BAe ATP runway excursion, Birmingham