NTSB · Safety Recommendation
Safety Recommendation A-21-021
Recommendation
TO FOREFLIGHT: Update your traffic alerting algorithms so that traffic targets for which there is no altitude information are assumed to be at the same altitude as the ownship (that is, the aircraft receiving the target data).
Safety Issue and Context
On May 13, 2019, about 1221 Alaska daylight time, a float-equipped de Havilland DHC-2 (Beaver) airplane, N952DB, and a float-equipped de Havilland DHC-3 (Otter) airplane, N959PA, collided in midair about 8 miles northeast of Ketchikan, Alaska. The DHC-2 pilot and four passengers sustained fatal injuries. The DHC-3 pilot sustained minor injuries, nine passengers sustained serious injuries, and one passenger sustained fatal injuries. The DHC-2 was destroyed and the DHC-3 sustained substantial damage.
The DHC-2 was registered to and operated by Mountain Air Service LLC, Ketchikan, Alaska, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135 as an on-demand sightseeing flight. The DHC-3 was registered to Pantechnicon Aviation LTD, Minden, Nevada, and operated by Venture Travel, LLC, dba Taquan Air, Ketchikan, Alaska, under the provisions of Part 135 as an on-demand sightseeing flight. Visual meteorological conditions prevailed in the area at the time of the accident.
According to information provided by the operators, both airplanes had been conducting sightseeing flights and were both converging on a scenic waterfall before returning to the Ketchikan Harbor Seaplane Base (5KE), Ketchikan, Alaska, when the accident occurred. Automatic dependent surveillance-broadcast (ADS-B) tracking data for both airplanes revealed that, at 1217:15, the DHC-3 was about level at 4,000 ft mean sea level (msl) on a track of 225°, and the DHC-2 was 4.2 nautical miles (nm) south of the DHC-3, climbing through 2,800 ft msl, on a track of 255°.1 About 1219, the DHC-3 started a descent from 4,000 ft, and the DHC-2 was at 3,175 ft and climbing.
During the next 1 minute 21 seconds, the DHC-3 continued to descend on a track between 224° and 237°, and the DHC-2 leveled out at 3,350 ft on a track of about 255°. The airplanes collided at 1221:14 at an altitude of 3,350 ft, 7.4 nm northeast of 5KE.
Response History
December 13, 2024 · NTSB Correspondence · ForeFlight
We note that you have updated ForeFlight’s traffic alerting logic so that traffic targets with missing altitude information are assumed to be at the same altitude as the aircraft receiving the target data, and that an alert indicates that the target’s altitude is unknown. We also note that you have updated your Pilot’s Guide to include this information.
We believe these actions satisfy the intent of Safety Recommendation A-21-21, which is classified CLOSED-- ACCEPTABLE ACTION.
Thank you for your efforts to improve aviation safety.
November 1, 2024 · Recipient Response · ForeFlight
-From Kevin Sutterfield, Chief Revenue Officer, ForeFlight: I am pleased to report that we did take action back in 2021 regarding the NTSB safety recommendation we received (but we likely failed to update you on our progress). I’m including details below and have attached a screenshot for your visualization. Thank you again for your time and for the productive dialogue on the future of aviation safety. We look forward to our ongoing collaboration in pursuit of safer skies.
In 2021, the ForeFlight Mobile application was updated to: (1) display traffic targets not reporting altitude on the map (even with the "Hide Distant Traffic" setting enabled), and (2) produce visual and aural alerts for traffic targets with missing altitude, as depicted in the attached screenshot. As recommended by the NTSB, the updated alerting logic assumes traffic targets with missing altitude information are at the same altitude and the alert indicates that the target's altitude is unknown.
May 21, 2021 · NTSB Correspondence · ForeFlight
The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant accidents in other modes of transportation—railroad, highway, marine, and pipeline. We determine the probable cause of the accidents and issue safety recommendations aimed at preventing future accidents. In addition, we carry out special studies concerning transportation safety and coordinate the resources of the federal government and other organizations to provide assistance to victims and their family members affected by major transportation disasters.