Anatomy of a Cirrus Stall Accident

if you've ever looked closely at a Cirrus aircraft you've probably wondered about this split leading edge hello everyone I'm Paul Berta le reporting for Aviation Safety and AB web the split leading edge is part of what Cirrus calls its passive safety concept as you know every aircraft has a stall angle of attack for most wings that's about 17 degrees but since the early days of the Wright brothers we as pilots have been struggling with the ability to control roll through a stall and that's what this split leading-edge does Sears his idea was to build in a slightly lower angle of incidence on the outer panel than on the inner panel the effect of this is that the inner panel stalls first the outer panel continues to fly and you maintain roll control with the ailerons now if you've ever flown a Cirrus and you've done stall demos you know that this works exactly as advertised however as the accident we're going to dissect in this video shows it's not foolproof if you use abusive control inputs even the split leading edge won't protect you here's the setup this accident occurred in February of 2008 at Lindsay Oklahoma which is just south of Oklahoma City the flight took place close enough to Will Rogers Airport to be tracked by terminal approach radar according to the NTS b--'s accident report the pilot of the Cirrus sr22 took off with an instructor to complete a flight review the airplane evidently flew northwest of the airport and performed some maneuver before turning back toward the airport it's at this point that things began to unravel although the pilots intentions are unknown he appears to have flown a path that would have put the airplane on a right downwind for runway 1 as shown in this graphic the wind that day was out of the East at 5 knots so either runway 1 or 1 9 would have been suitable whether he intended to use runway 1 or not the pilot then made a sharp right turn with a steep Bank that essentially put the airplane on a left base for runway 1 9 but on a heading angled slightly away from the perpendicular base leg a few seconds later he made a sharp turn back to the left possibly in an attempt to line up with runway one nine or perhaps to enter left downwind for runway one the accident report isn't clear either way it didn't work out the airplane crashed a quarter mile north of the airport killing both aboard had there been no witnesses this accident might have been just another of dozens like it where an airplane digs a smoking crater for no apparent reason but there was a witness and a very good one like all recent model series aircraft the sr22 had a glass panel suite the avid ein Integra despite the post-crash fire the NTSB retrieved enough data from the Integra to reconstruct this flight in this video here's what the investigators found at this point in the fight the Cirrus is descending for that abortive right downwind significantly it's altitude is fifteen hundred and twenty feet which is only 555 feet above ground level and well below pattern altitude at this point it's entering the right turn and reaches a bank angle of 47 degrees the angle of attack increases from six point five degrees to 10 degrees in nine seconds that's a moderate pitch rate increase but hardly aerobatic manoeuvring the wings weren't yet heavily loaded because the airplane was still descending slightly a second later as the airplane was flying through the runway centerline it rolled sharply left through wings level to a left bank angle that reached sixty degrees the angle of attack increased from 10 degrees to 17 degrees at this point the airplane is at 223 feet AGL despite the sr22 stall resistant wing the flight data indicates that the entire left wing was above the stall angle of attack this may have increased drag on the wing and adduced more left yawning moment essentially an incipient spin the left aileron would have almost certainly been out of the game at this point surprisingly two seconds later the airplane rolled violently right pitched down and crashed when it reviewed the data carefully the investigators found out why a fraction of a second before the final right roll started the data showed a clear right yaw moment and that's evidence of right or top rudder application if the pilot sensed an incipient spin to the he might have countered it with full right rudder but unless the wing is unloaded to break the stall that's not counter spin input its a snap roll entry and that's apparently what happened in this accident here are some final observation you might say that this video shows that the more things change the more they stay the same the accident we've seen in this video is very typical of the type of stall spin or stall accident that airplanes have been doing the traffic patterns for years for some reason we can't seem to learn that steep banks and high load factors in the traffic pattern invite disaster they should be avoided at all cost it's that simple to find out more about this accident see the January 2010 issue of aviation safety at aviation safety magazine comm elsewhere on Ave web you can hear a podcast with John King and rich stole two veteran instructors disgusting stall spin accidents I'm Paul Berger le reporting for aviation safety and AB Webb thanks for watching

Channel: AVweb

Views: 745,485

Rating: 4.8649025 out of 5

Keywords: AVweb, general aviation, Cirrus, SR22, stall, stall/spin, NTSB, Lindsay, Oklahoma, Paul Bertorelli, aircraft accident

Id: 7nm_hoHhbFo

Length: 5min 32sec (332 seconds)

Published: Fri Dec 18 2009

Reddit Comments

[u/smeezy]

Sobering. But I wonder what prompted those crazy maneuvers? And with a CFI on board, no less.

[u/[deleted]]

My .02: This accident started long before the stall happened. We don't know what they were trying to do with that maneuvering, but it doesn't seem from the data that they did either. It was a bad plan from the start. If you need 60+ degree banks to line up with the runway, you've already failed. Go around and try again.

My argument falls apart a bit if the engine wasn't running, but that didn't seem to be the case in this crash.

[u/[deleted]]

Why is that bikini chick in all these aviation "Related videos" at the end of everything?

[u/SDPilot]

This calls for "Pull the chute" comments.