jlunseth

Well, I would check the Aspen manual and see what it says about using the NAV mode of the autopilot with the Aspen. Perhaps the Aspen operates differently from the gpss + analog AP systems I am familiar with. So there are as I understand it, two ways these systems operate. With the autopilot in approach mode, the system is wired so that the AP uses the RWY "X" waypoint in the same way it would use an analog ILS signal. It uses the waypoint for guidance straight in to the waypoint. You set the course needle for the inbound course and it flies that course just as it would an ILS or a VOR approach - by flying straight along the course line to the endpoint. The AP itself is computing the course using the waypoint. The roll steering works differently. What I am familiar with is to put the AP in HDG mode and enable the roll steering. The gpss then gives constant guidance to the analog AP through the HDG bug, to essentially fool the AP to fly the course guidance provided by the Garmin and the gpss. That guidance does not need to be straight line guidance, and that is the beauty of roll steering. The roll steering + Garmin can, for example, anticipate interception of the final approach course and begin a turn to intercept rather than flying to the final approach course and then making the turn, which results in going through the course and correcting back. The roll steering + Garmin can also fly approach courses that are curved, and there are a few, particularly up in AK. The NAV mode, as I understand it, works in the same way as putting the AP in approach mode except with greater tolerance for course deviation, that is, it accepts a waypoint from the Garmin and then flies straight to that waypoint along the course you have dialed in with the course needle, as though flying to a VOR that you have tuned in and set a course to. The AP is computing the course and not using course information from the roll steering + Garmin (except for the endpoint). That is how my system works, and a couple of others I have flown with, but I have not flown with an Aspen, maybe it does something different. Definitely not an avionics guy, but my understanding is that the wiring is such that the signal bypasses roll steering and goes directly to the AP from the Garmin, if the AP is in APCH or NAV mode, and goes through the roll steering function only if the AP is in HDG mode and roll steering is enabled. I could be completely wrong, I have not flown with an Aspen, but I would look it up. Another explanation which I have run into is that when the gyro in the 256 begins to fail, it does that. When mine went it kept me persistently right of course at cruise but worked fine on approach. Eventually it began to fail on approach also, which is when I got it replaced and thereafter, no problem.

I don't think a rapid pull up is necessary. I think of the phenomenon this way. In normal flight the wings generate upward lift and the horizontal stabilizer generates counterbalancing lift that keeps the nose up or down to cause level flight. If the aircraft suddenly enters a steep dive, it is actually doing the beginnings of an outside loop. During the initial phase of that loop the lift from the wings is positive, that is, upward along the vertical axis of the aircraft if the aircraft were in normal flight. The angle of attack begins to change and at some point, who knows exactly where, the lift generated by the wing becomes negative, that is, in a downward direction were the aircraft in a normal horizontal position. I am certainly no aerodynamics engineer, but in my mind if the aircraft already has some movement in a horizontal direction and it starts to go vertical, the angle of attack may change to the top of the wing (negative angle of attack) before the aircraft reaches vertical. When, in this transition, the horizontal stabilizer fails, the counterbalance to the wing's lift is suddenly removed, the wing either does an immediate upward movement if the wing lift is still positive, or an immediate downward movement if the lift has gone negative. When it does so, the angle of attack of the - now high velocity - apparent wind also changes abruptly, it increases. That movement abruptly increases the lift being generated by the wing, and if that lift exceeds the load capacity of the wing, the wing fails. It does so either in an upward or a downward direction depending where in that incipient outside loop the aircraft is, that is, whether the wing is generating positive or negative G's at the moment of stab failure. That explains why, in some accidents, the departure of the stabilizer has caused a negative failure of the wings, and in this most recent one, a positive failure. However, neither failure mode necessarily requires a rapid pull-up by the pilot, it simply requires the departure of the counterbalancing stabilizer from the airframe. Could a pull-up start the sequence? Sure. Is it necessary? No. All that is needed is an abrupt change in the angle of attack caused by the loss of the counterbalancing stabilizer.

Dev, I did some searching and found a couple of others. They are not easy to find because they have been so few in number and the Mooney has been around long before the internet, therefore records are not necessarily in a searchable database, and I may not have found all. One was a one-line report of a spar failure in an M18C. "A72 Mooney M-18C 31 Mar 64 1 D Roanoke Rapids, N.C. USA. Wing failure (spar). Ref: NTSB file 2-1036" https://apps.dtic.mil/sti/pdfs/ADA137254.pdf The other was a J. https://aviation-safety.net/wikibase/44066 There may have been another J in California, I could not find enough of a record to verify. The Rocket and J were wing failures, but both were different from the current accident in that the failure of the horizontal stabilizer reportedly caused the wing to fail in the negative direction, that is, upward if the aircraft had been right side up at the time. In the Rocket incident the factory concluded that the failure of the stabilizer caused the aircraft to tumble up and over, hence the negative wing failure. As we know, structural integrity in the upward direction is about half that in the downward direction, or at least that is how the FAA rates normal category aircraft. The issue of concern to us as Mooney pilots is that there have been at least four incidents now, of failure of the horizontal stabilizer and elevator, which likely is a flutter issue, not a load issue. This video has been around forever and is worth watching for anyone who needs a lesson in the effects of flutter. Turn the sound off, the music is aggravating. The lesson is that we cannot exceed Vne. Not that any of us have been going around doing that just for fun, but rather, if put in a potential accident scenario we must obviously protect Vne at whatever cost. Also, I was the one who said 800 based on having looked at the weather off and on during the day, earlier than the accident. Scott Dennstaedt gave us a RAOB that put the ceiling at 1200 and there were a few others who provided more current weather. Not that an extra 400 feet would make that much difference to your point about the force required to fail the wing by pulling up. From the sparse accident history it does appear that failure of the wing can be caused by the failure of the stabilizer. It appears to me it would be fair to say, though, that this is the first time that has occurred in the positive direction rather than the negative (excluding the Mite accident in 72 - different wing).

I don’t think there is a reason to criticize the controller. The intercept altitude for the ILS 10R approach is 2700. The NTSB guy, in one of the interviews, says that is the approach the aircraft was on. The other intercepts (RNAV’s 10R & L)are 2700 and 2800. The aircraft was at or above intercept altitude at 17:39:39 on the ADSB graphic (and continuously before that), just 8 seconds before it impacted at 39:47. If you listen to the animated tape, tower called two or three times. Someone else earlier in the thread made the opposite comment, that the controller should have kept quiet. In this instance there was not time for the controller to make any difference.

Thanks Scott. The cell that was east later in the day, looked as though it would have passed well south of the accident site. It does not appear he ran into a cell.

The NTSB gave a press conference, I believe yesterday. Its on Facebook. https://www.facebook.com/KSTPTV/videos/978394926281658/?t=7 Not much additional informational that we do not already have, except the NTSB rep makes clear that it was the left stabilizer and elevator that departed the aircraft. He says nothing about the right assembly so I would assume that was on the aircraft when it impacted. Three people in the aircraft, sadly all deceased. Two in the house, fortunately uninjured. He says things like, "the plane was 10 miles out and on final" without saying the magic words "instrument approach," but he confirms there was a solid deck.

The tower cleared him to land on 10R according to the tape. The main approaches are the 10R ILS and the 10R RNAV. There is an RNAV to 10L, but the approach lights are at 10R, that is a nice, big long runway compared to 10L, and the 10L approach is not used much if at all. I have never flown it. Not significant to the accident since all the one-zero approaches start out in the area where the crash occurred, just information.

It would be helpful to have the Approach tape that preceded the tower communications. Approach on that side of the airport is 134.7. Approach would have cleared the pilot for the approach and would have done any vectoring, then handed him off to the tower when he was on the final approach course. If there was a warning about a cell on final, approach might have done that rather than tower.

Thank you for the actual weather Scott. He was landing on 10R according to the ATC recording, that would have put the aircraft right at intercept altitude for the ILS or the RNAV 10R into FCM. There was a cell that had passed to the east by the time I heard about this accident and looked at the wx at around 8 pm. It was small in diameter but the top was 37k or better. Is there a way to retrieve the NEXRAD at the time of the accident, which apparently was around 6:40 CDT? This is speculation, but the pilot deviated left of the final approach course a little, and that may even have been before he penetrated the deck if the deck was 2900. It is possible he was trying to avoid a cell sitting on the final approach course or a little south of it. That would help explain a deviation to the north to avoid the cell, then a correction back south to get on the final approach course, and then an immediate turn to the north if he ran into the cell again.

No, not that much, I remember the 600 down. There is a tower ride at an amusement park in that vicinity, which concerned me at the time. I experienced enough to say that it is very difficult to re-establish equilibrium in IMC when it becomes impaired. The AI is very important, partial panel is next to useless. If I can put in a plug, I decided a couple of years ago that the main area in which my training was lacking was recovery of severe upset in IMC. I went to APS in Pheonix and took their excellent upset recovery course, which included incipient spins on instruments. It was costly, fun, and I have not regretted it. However, even they focus on stalls and stall/spin recovery. Regaining instrument control from an uncontrolled accelerated descent or dive in IMC in severe circumstances - I am not sure anyone trains it.

Is there some evidence he was not on an approach or had not filed IFR? Flightaware does not have that information. I don’t see how that would have been possible that day. His cruise was at 5,000, there would have been a solid cloud deck between him and the ground, and at 5,000 he might have been in the clouds there also. As I mentioned earlier in this thread, all the approaches to 10R & L start in the vicinity of the crash and at the altitude he was flying (2,900 vs. intercept altitudes of 2,700 or 2,800 depending on the approach). The course he flew looks like a vtf to 10R at FCM with a light deviation left of course starting near Victoria, but could have been an RNAV to either 10R or L. @Shad, your graphic is very helpful. I have to say that I have experienced similar altitude excursions on approach into FCM because of heavy convective activity, although it was on the other side of the airport, south over the Minnesota River. If there was a cell passing through that area, and there may have been, then those altitude excursions are more violent and exaggerated for the most part, than what I experienced, but they do not surprise me. Down 600, up 400, all in less than a minute or so it seemed. FCM tower got me the heck out of there. In my case the autopilot disconnected because it could not maintain control, it is one thing to hand fly in those circumstances and another to have control turned over in those circumstances with no notice.

Thank you mhirvnak, that makes the most sense of all. Bear in mind the break out altitude was low all day, somewhere around 800. A witness would not have seen the plane until it broke out. The pilot may not have understood his attitude until he broke out. He may have tried to pull up and then everything went, or I suppose it is possible the stab departed because of flutter and that did it. Which one, we will probably never know. I think we do know now that the wing is not invulnerable.

It would depend on where the center of gravity is, with the possibility that the load may have shifted in severe turbulence. Also possible that the engine us running and the prop is acting to try to lift the nose, sort of like a helicopter blade would. Yes, normally you would be correct and I am only presenting it as a possibility. I like A64’s word, “shuttlecock,” better than my description. If you think of the aircraft as falling like a shuttlecock instead of flying, then all of our normal aerodynamic ideas convert to something else. I also am mindful of the early witness description that the aircraft was spiraling, could be a stall/spin or could be a shuttlecock descent - or like many eyewitness descriptions could just be wrong.

I personally don’t agree that that is the case. The wing root area that is painted maroon on the underside extends too far up the side of the cabin, as though the wings are folded in the first picture. But it is certainly a valid question to ask. Hopefully, the NTSB will have the original video and excellent tools to examine it with, and can ultimately give an answer.

I see there is a post suggesting there might have been an abrupt pull up by the pilot. That is a possibility, but in light of the fact that the stab and elevator departed, their loss may have caused an abrupt pullup motion. The pilot may have had no control at that point. Whether the loss of the stab and elevator caused a pullup, or an encounter with severe shear conditions inside a thunderstorm caused simultaneous loss of multiple aerodynamic surfaces, we cannot know at this point. As for dxb’s thoughts, honestly, I think this has been a very professional debate so far. All the right questions have been asked including his. Anyone who has ever been part of a scientific debate knows that it is healthy to have multiple strong and competing views involved, that is what, hopefully, leads to finding out what the real facts are. I am impressed with the quality of this discussion, maybe the NTSB will see it and it will prompt some science-based questions during the investigation. Bear in mind that this is the only time as far as any of us know, that there has been some evidence that a Mooney wing failed in flight. There had better be some strong questions asked on all sides.

With respect, the aircraft is not flying at all towards the end of the flight and in the video. It is falling like a leaf. The vertically folded wings would have the effect of keeping the aircraft upright. There would be a “parachute effect,” that is, the wings would cause drag in an upward direction, keeping the belly down. It may even have been rotating around a vertical axis. The aircraft is nose up simply because its center of gravity is behind wherever the center of the upward drag effect of the wings is.

https://kstp.com/news/ntsb-resumes-investigation-into-small-plane-crash-that-killed-3-victoria/6202221/ This is a video from a local TV station showing an NTSB rep stating that the elevator and horizontal stabilizer had departed the aircraft prior to the crash, it is a little after 1:50 on the video. Several others have mentioned this, but it seems to be getting ignored in the “artifact” debate. The lack of a stab and elev would explain the nose up attitude seen during the fall in the crash video. As the NTSB rep says, lacking a horizontal stabilizer and elevator the plane would not continue to fly. The video also shows the right wing being handled by two workers. That is immediately after the NTSB rep speaking in the video. The wing is upside down with the flaps visible. It is a little difficult to see all of the tip, which is partially blocked by a pickup, but there is no apparent damage to the wingtip area that would have been caused by that wing hitting the ground first with the plane tilted right. The wing is essentially intact except for the maroon colored “wingwalk” area. For those just tuning in, I am putting “wingwalk” in quotes because I know that there is no wingwalk on the port side, but it helps to explain the area of this wing that was painted maroon top and bottom - about the first two feet from the fuselage on both sides. Early reports are pointing towards an inflight breakup, whether the wings folded or not we will know soon enough.

If you look at the picture of the aircraft in the hangar on aircraft.com, the first two or three feet - basically the wingwalk area - is painted maroon top and bottom. The same color shows at the bottom of the folded wings. The NTSB will have the full video and will make a determination.

No, I am sorry, but the speculation that the impact caused the wings to fold is not accurate. Go into the video in youtube, hit settings and set the video to play at the lowest speed (0.25). At 17:40.04 hit the “k” key which stops the video. Then use your right and left arrow keys to step through the video. These controls do not work perfectly every time, but if you play with them you should be able to watch the aircraft fall at slow speed. You may have to exit the video and enter again to get the controls working properly. Both the right and left wing are folded vertically before the tail of the aircraft strikes the ground. The leading edge of the right wing is plainly visible behind the left wing. It also appears that the flaps and ailerons may be gone but I am not going to speculate on that, the NTSB will figure it out. The time stamp on the video obscures the crucial point where the ailerons would be at the fixed wingtip, so it is difficult to see whether that point is protruding backwards with no aileron attached. The quality of the video is quite good on my screen.

Dev, look at the video and the freeze frames someone was kind enough to put up. The wing is already folded before the aircraft strikes the ground, they do not fold at the moment of impact.

I completely agree Anthony. However, I remember reading somewhere that the up and down drafts in a tstorm can cause virtually instantaneous changes in the airspeed that the wing experiences. In other words, the aircraft may be traveling horizontally at Vne, but is struck by up or down drafts many times that speed, which means the wing is well over Vne. Especially so in the “sheer wall” between where the storm is sucking up warm moist air, and where it is dumping down cold air and rain. This is why we all stay away from red cells. We get violent microbursts and straight line winds here in the summer. Not all the time and not everywhere, but they certainly happen and can be violent. A64 is right on that one. Having been in that spot at that airport before, and this is sheer speculation, that is what would cause the pilot to be less than responsive on the radio. Way too much going on and you are just trying to keep the white side up, the greasy side down, your head off the headliner, and some space between you and the earth. Here is the panel. It was a standard 6 pack with 530 and 430W’s. The specs say it had a stormscope. https://www.aircraft.com/aircraft/1207543/n9156z-1991-mooney-m20m-bravo

The tower controllers at FCM are just exceptional, I fly with them nearly everyday. Over several years I have listened to them deal professionally with all manner of unusual situations, including me on one or two occasions, and I have found myself in extreme turbulence on final there from which that tower quickly rescued me. I am going to speculate that tower called two or three times in succession at the end of that tape because it had just lost the aircraft off the scope. They were trying to help.

He was right on the button for one of the approaches into FCM until the last few seconds of the flight. Intercept altitude is 2700 or 2800 depending on which approach and the RNAV 10L allows descent to 2100 in that area, the others keep you at 2700. The field is 906 and there is not much in the way of terrain out west, where he was. Clearly from his contact with tower something was going on, health or distraction in the cockpit. He had to be on approach at some point, it was hard IMC all day yesterday (and still is as I write this). However, the flight track was deviating slightly left of course - about 400 - 600 yards, then trying to return to course, then turning 180 due north away from the approach course in the last moments. Could have been a cell on the approach course he was trying to avoid, and heavy turbulence, but if there was, ATC or FCM tower would already have warned him. There would have been no bounce, there are trees and structures on the other side of that street that the plane came from, he would have hit something. I just walked that street a little over a week ago and had dinner about two blocks left of where the plane ended up. Yes, thoughts and prayers to everyone involved.

It does look like at least the left wing is folded completely vertical and possibly the right wing. Need to look at both photos to see it. I looked at NEXRAD at about 8 pm. There was a small cell that had moved through the south metro, high 30 thousands, relatively small in diameter. It was well east of the metro by the time I looked and should have crossed south of the accident site, but it might have crossed there. ATC and/or tower would have warned about it if it was sitting on the final approach course if they followed their normal practice in this area. Maybe someone could find the tower or approach control tapes. Tower is 119.15 and approach is 134.7 in that area. PS I found the video. Both wings are definitely folded in the air.

The course near the Twin Cities looks like a vectors to final to either the ILS 10R although it could possibly be a VTF to one of the two RNAVs to either 10R or L. It appears from the very end of the course that the aircraft had intercepted the final approach course around Lake Waconia and was inbound. There is a slight deviation left of course immediately before the flightaware track prematurely ends, pretty much exactly where the accident site is, south of Lake Auburn or Stieger Lake, right in Victoria. It appears the aircraft was correcting back to the final approach course. I don’t see a 9600 FPM descent speed though, the last descent speeds in flightaware are in the hundreds of fpm. It was a well equipped aircraft according to aircraft.com. 530W/430W and KFC150 unless further updated. That system should have been able to fly the aircraft right down to the runway on autopilot.