The National Transportation Safety Board (NTSB) has released a safety alert advising on the risks and preparation necessary to perform circling instrument approach procedures. The alert, “Circling Approaches: Know the Risks,” was released as the NTSB has been preparing a report on its investigation of the July 2021 Bombardier Challenger 605 accident in Truckee, California, that involved an unstabilized circle-to-land approach. In addition, the Safety Board released the alert to coincide with the Air Charter Safety Foundation’s (ACSF) Safety Symposium last week.
Board member Michael Graham was among the slate of speakers at the ACSF event, providing an overview of the publicly available facts in the Truckee accident. He cited that accident—as well as ones that involved the May 2017 Learjet 35A crash in Teterboro, New Jersey, and the December 2022 Learjet 35A accident at Gillespie Field in El Cajon, California—in the development of the safety alert.
In the alert, the NTSB noted that since 2008, 10 accidents involving Part 91 and 135 operators have occurred during a circling approach and have resulted in 17 fatalities. These approaches can be riskier because they require maneuvering at low altitude and low airspeed, increasing the opportunity for loss of control or collision with terrain, according to the Safety Board.
Further, circle-to-land maneuvering often results in an unstabilized approach, the agency added. While sometimes necessary, pilots don’t always evaluate the risks before accepting them, it further noted.
The safety alert advises operators to fully understand the risk involved, consider their own experience and limitations such as weather and runway configuration, and know that they may be able to request alternatives. Further, the NTSB recommends scenario-based training in realistic environments for such approaches and stresses the need for a comprehensive briefing before performing such an approach.
In outlining the facts of the Truckee accident, Graham noted a number of issues that were uncovered during the investigation ranging from the fact that four passengers were aboard even though only three were on the manifest, the captain was not a U.S. citizen but had an incorrect visa, the captain and copilot did not appear to have received basic indoctrination training nor an operating manual, and there was no record of a weight-and-balance calculation. The operator had its Part 135 certificate for 13 days and this was the first time the crew had flown together.
The crew had briefed on a straight-in RNAV approach to Runway 11 but initially accepted an RNAV Runway 20 approach that ATC had given them. They never briefed for that approach and ultimately requested a circle to Runway 11 because Runway 20 was too short. ATC offered for the flight crew to enter the left downwind leg for Runway 11 or to cross over the airport and enter the left downwind for the corresponding Runway 29.
The crew opted to maneuver to enter the traffic pattern for Runway 11. But the aircraft passed the centerline and entered a steep left turn in a nose-down attitude and crashed as it was maneuvering too close to the ground with an incorrect configuration and speed. All six aboard died.
There were options that could have provided for a stabilized approach, the NTSB noted, such as requesting the original approach they planned for, briefing for the approach they initially accepted, or performing a missed approach.
Graham pointed to a Flight Safety Foundation finding that runway-aligned approaches are 25 times safer than ones that are not. As far as the guidance, Graham emphasized, “If you are going to do a circle-to-land approach, you need to understand your risk and before you even think about doing one of these, [you should] know your…personal experience level. Are you comfortable with the limitations of the weather? The capabilities of the aircraft? If you’re not comfortable with the approach, don’t accept it.”