On the heels of the NTSB’s Nov. 14 release of its “Most Wanted” list of transportation safety improvements that included general aviation loss of control, the University of North Dakota, in partnership with the Aircraft Owners and Pilots Association (AOPA) Air Safety Institute (ASI), have launched a study of the use of a continuous turning approach or “circular pattern” as an alternative to the traditional “box” or rectangular traffic pattern.
Reduction of in-flight loss-of-control accidents continues to be identified by the NTSB as a most-wanted safety improvement.
Working with senior NTSB officials at a recent loss-of-control panel, the idea was formed that UND and AOPA team up to explore how simple procedural and training methodology changes in the landing pattern might improve safety and reduce loss-of-control accidents.
The hypothesis to be studied is that in contrast with a rectangular pattern, a continuous turn from downwind to final may provide for increased stability, reduced pilot workload, and a constant bank angle throughout the maneuver, helping pilots better manage angle-of-attack variances.
Additionally, the use of a continuous turning approach has the potential to reduce the likelihood of overshooting a runway during base-to-final turns, a scenario that has resulted in multiple stall/spin accidents due to aggressive corrective maneuvering.
Depending on the results of the study, this procedure may serve as a mitigating technique to reduce the likelihood of loss-of-control accidents during the landing phase of flight.
“It’s too early to say for sure if the continuous turn to final method will be a safer, more stabilized way to land. But what we do know is general aviation has been flying the rectangular pattern for decades, and based on substantial loss-of-control accident data in the landing pattern, we believe it’s time to conduct research to determine if there is a potentially safer alternative,” said George Perry, senior vice president of AOPA’s Air Safety Institute. “The U.S. military, commercial airlines, and many airline ab initio programs already utilize the continuous approach turn as the standard to support safe landing pattern operations. We should determine which is safer for general aviation, and this study will help us find the answer.”
“The research will consist of flight data analysis to evaluate differences between the circular pattern and the rectangular pattern,” noted Lewis Archer from UND’s aviation department. “Variables that will be analyzed include bank angle, airspeed, and runway overshoot.”
“Although the study is in its early phases, and it’s far too soon to draw any definitive conclusions, the new procedure has already been studied and practiced by a select group of UND instructor pilots and initial data collection has been going quite well.”
The study is ongoing, and both UND and the Air Safety Institute are hopeful that results will be available sometime in early 2017.
I use cicular type and think it is an easier way to fly the pattern, by far. Another key element of my technique is that I fully configure landing gear, flaps, cowl flaps, props and mixture at the abeam point. It makes for a tight pattern with correct trim being set early- the airplane transmits via stick forces if airspeed is in the zone for landing. I have 21,000 TT and currently fly a Grumman Widgeon. Other planes- Pitts, Cessna 180, Baron, Aztec and Helio Courier. Circle type is best in all of those. Airbus300/B757/B727 Carib/SA division. Douglas A4,A3 carrier ops: Configure at the abeam and get a stable approach and a happy landing. AGL alt: 900′ abeam/600’@90/300′ in the groove at start of final. Box pattern simply does not work as well due distractions and difficult cross check points.
I would argue that a constantly curving pattern from downwind to final means that you are less likely to overbank (i.e., pull back too much) and stall because you eliminate the sharper turns at the corners. I fly a high-wing airplane and am based at an airport with a tight downwind (mountains adjacent) and a 600-foot pattern altitude. Those who fly squared-off patterns here have more difficulties than those who turn constantly from downwind to final.
Very interesting. I’ve used circular pattern approaches in low wings and I think they are an advantage. The military, airline, and ab initio programs mentioned would be low-wing operators. But with small high wing aircraft, where you will have the runway out of sight for a substantial time, I don’t see how that could even be considered as a better way. If any test instructor finds the circular pattern works better in a high wing (i.e. Skyhawk), I would like to see details of the testing – i.e. were the tests done at a proper variety of unfamiliar airports in different weather conditions, or repeated at a familiar airport where the instructor could fly the pattern with his eyes closed. Using a constant bank angle wouldn’t reduce pilot workload but increase it because it would not keep the airplane on the proper groundtrack as the wind component changes from tailwind, crosswind, to headwind and the further you proceed on the wrong groundtrack, the adjustments eventually needed will increase. Overshooting base to final most likely starts with a poorly flown downwind where the aircraft gets blown by a crosswind too close to the runway. This study should also include and carefully evaluate the entire downwind leg of the pattern. In many cases that’s probably where the problem starts.
Wow. Innovation.
Rectangle sez: “But that’s the way we’ve always done it!”
Semicirc sez: “Siddown n shaddap!”
Buncha pilots say: “what took ya so long?”
???????? ?? ?? ?? ?