Stalls in the Pattern

[WLIU]

"most pilots try to rudder around the base to final" - I am not willing to engage in that generality any more. It sounds good to folks looking for an easy point of blame, but my personal observation is that these days "most pilots" do not use the rudder for very much. The airplanes that are used for training hardly need any rudder inputs at all. The common rental aircraft need hardly any rudder inputs. So my conclusion is that it is unlikely that "most pilots" resort to over-ruddering the base to final turn. When I fly with other pilots I often find myself thinking that too many of my peers under use the rudder. I would find a theory that involved over banking or over elevator-ing, with inadequate rudder coordination more likely. That said, that sort of pilot error could simply result in a spin away from the turn rather than a spin into the turn, so without more info any theory could correctly explain the data.

Speculation on inadequate data produces questionable educational value.

Be safe,

Wes
N78PS

[Bill Greenwood]

The accident report does not give much info on the pilot, how many hours he had and how many in type, so it is hard to judge his experience level. but it does say he already made two landings that day. No weather data given, so I don't see where you guys are getting a tailwind on base as a factor.

Would an AOA indicator have helped. Well, if he had a clogged pitot or some airspeed indicator malfunction, and the AOA came from a separate source, it could have helped, but only if he looked at it.
I wonder if he really did 2 stalls and recoveries at low altitude on the previous approaches or if he might have been hitting wake turbulence from other planes as it was a fly in.

It seems strange that we don't know anything about radio talk with the advisory tower while he is doing the 3 approaches.

[rwanttaja]

The accident report does not give much info on the pilot, how many hours he had and how many in type, so it is hard to judge his experience level. but it does say he already made two landings that day. No weather data given, so I don't see where you guys are getting a tailwind on base as a factor.

Looked up the pilot's license information. He got his Private ticket just over three years ago. It's probable he had less than ~300 hours. This data isn't available in the preliminary, but this and any weather data will come out in the factual (~10 or so months from now). As Bill mentioned, he had landed fine twice earlier that day, and two other RANS landed about the same time without mishap.

Going to be out of pocket for a few days, but when things settle down, I may call the NTSB investigator for a bit more information.

I did check, it appears his passenger did not have a license.

Would an AOA indicator have helped. Well, if he had a clogged pitot or some airspeed indicator malfunction, and the AOA came from a separate source, it could have helped, but only if he looked at it.

I've never flown with an AOA, but the more I think about it, the better idea it seems.

In my experience, a clogged pitot makes the airspeed read too low, not too high. I had a clogged pitot line in my student days, and the biggest danger was me shoving forward thinking the plane was about to stall. The gauge indicated pretty much OK at pattern altitude, but when I descended on final the airspeed dropped (increasing static pressure with the decrease in altitude gave the same indication as decreasing pitot). I kept shoving the stick forward to try to "correct" it. Scared the bejesus out of me, especially when airspeed descended past zero. Take my word for it, the actual airspeed getting TOO slow never was a danger. :-)

However, if the static line stopped up, I think there'd be a danger of the airspeed reading too high. As the plane descended, the pressure on the pitot side would rise due to the higher atmospheric pressure, which would make the indicator read higher than actual.

I think I've got an old airspeed indicator sitting in the parts box. I might rig up a temporary mount and pitot/static connection and play around with various failures.

I wonder if he really did 2 stalls and recoveries at low altitude on the previous approaches or if he might have been hitting wake turbulence from other planes as it was a fly in.

It seems strange that we don't know anything about radio talk with the advisory tower while he is doing the 3 approaches.

The preliminary report is basically taken from the immediate interviews, so it may not reflect everything that was going on. Since it was an advisory, apparently unofficial, tower, there wouldn't be any recordings to listen to.

Ron Wanttaja

[Janet Davidson]

Wes,

Just a quick correction, the accident to which you refer in you first post was Swissair, not KLM. http://en.wikipedia.org/wiki/Swissair_Flight_111

[Frank Giger]

Hmmm, a lot to take in.

First, I'll agree that spin training and flying without looking at the dash is good sense. I'm just a humble Sport Pilot and had both. One doesn't need to go under the hood to get some basic panel failure training. I'm beginning to think my CFI is way under-rated.

Of course I won't talk about the time the geewhiz glass panel of a CTLS decided to go completely dark on takeoff as part of the syallabus, because it wasn't. I will never own a glass panel because of it. No danger of wrecking if they decide to crap out, but having absolutely nothing but a compass because all the other instruments (tac, oil pressure, RPM, plus all flight instrumentation) are in one point of failure is unacceptable to me.

The Champ with a standard six seems more reliable to me.

Second, I've stalled on final. Not in the turn, but on line up. Classic case of aimpoint fixation - I wanted to land on my imaginary mark and pitched up to slow down and increase descent.....a little power and easing the stick did it (since I wasn't jerking the stick around walked up to the stall) and I landed a little long. 5,000 feet of pavement and I'm being dumb, focusing on erping the numbers in an aircraft that only needs 500 feet of it.

I'll also say that when I made the mistake I desperately wanted to go-around. It's drilled into one - crashes are expensive, go-arounds are free, so if something isn't right do the latter. I didn't though...I just landed longer than I had planned, shook my head at how stupid I can be, and did another touch-and-go, which set me up for nearly the same scenario (my personal goal for the day was short field landings), but I didn't fall for it and resigned myself to "regular" landings.

Passengers matter, particularly if one is introducing them to GA. The most stressful landing I ever made was when I conned* my wife into getting into the Champ. A rough landing would have convinced her that my hobby was dangerous and I was crappy at it. It was also the second best landing I've ever made....but I was sweating bullets the whole time.

* I lied and told her I needed a "passenger endorsement" to fill out my ticket.

[steveinindy]

The autopsy should settle this...there are characteristic injuries to the hand of the person holding the stick at impact.

Ron Wanttaja

Ron, the so called control surface injuries to the hands and feet are poor indicators of who was actively in control at the moment of the crash. A lot of known pilots do not have them (poor sensitivity) and a lot of non-pilots have them from contact with cockpit structures during crashes (poor specificity). Les Folio addressed this in one of his articles out of the AFIP. I can send you a copy of you like. Basically unless you have a black box or the hand is clenched in cadaveric spasm around the controls, there does not appear to be a reliable indicator as to who was in control.

[rwanttaja]

Ron, the so called control surface injuries to the hands and feet are poor indicators of who was actively in control at the moment of the crash. A lot of known pilots do not have them (poor sensitivity) and a lot of non-pilots have them from contact with cockpit structures during crashes (poor specificity). Les Folio addressed this in one of his articles out of the AFIP. I can send you a copy of you like. Basically unless you have a black box or the hand is clenched in cadaveric spasm around the controls, there does not appear to be a reliable indicator as to who was in control.

Gotcha, understand. Lots of tubing and whatnot for the passenger to be clutching....

I heard the hand-injury thing at an NTSB presentation ~25 years ago, undoubtedly the state of the art is improved.

Ron Wanttaja

[steveinindy]

Gotcha, understand. Lots of tubing and whatnot for the passenger to be clutching....

I heard the hand-injury thing at an NTSB presentation ~25 years ago, undoubtedly the state of the art is improved.

Ron Wanttaja

Well, among the folks who actually bother to read the forensic literature, yes it has. You still hear folks- including NTSB investigators and even their safety and survivability folks- treat it like gospel because it is so ingrained in the literature (there are references to it that I have found dating back to the 1920s) and lore of aviation pathology and crash investigation that you can't convince them otherwise. That is a major problem with these folks in that they treat the practice of investigation more like a religion rather than a scientifically grounded exercise.

You can also get similar injuries from someone's arms and legs flailing during the crash deceleration. This is an area that really needs to have more research before it is finally dismissed or is able to be applied in a more rigorous manner. Myself and a couple of colleagues (a forensic pathologist and a forensic radiologist respectively) are working on a retrospective review to see if we can do something about that.

[Mayhemxpc]

Just a couple of anecdotes about rudders, ASIs and low-time pilots...

Some years ago, when providing flight instruction at a Civil Air Patrol National Flight Academy, I overheard this joke told between the student pilots (All 16 and 17 year old cadets): "Why does an airplane have rudder pedals? To give the flight instructor something to say." At another iteration of the NFA, all 12 airplanes taxied out for departure together, shortly after a squall line came through (after pre-flight, before starting engines.) One of the first planes off quickly called back for a priority landing having experienced complete pitot/static failure. (There is more to that, but for another time.) We were number two for take-off and due for the line-up check. I asked the student, "Everything OK? Are we ready for take-off?" "Sure" came the reply. I then asked, "Do you really think we are doing 40 knots just sitting here?" While he was flummoxed, I advised all the other planes to drain their pitot static systems as part of the run-up check that morning.

Ruddering through the turn is possible but, as pointed out above, not too likely (the turns may have still been uncoordinated.) Blocks in the pitot-static system CAN cause a false high reading. That said, a pilot should be able to fly a light aircraft base to final SAFELY -- and land without looking at any instruments.

I will be very interested in reading the final report.

[Bob Dingley]

Ron, the so called control surface injuries to the hands and feet are poor indicators of who was actively in control at the moment of the crash. A lot of known pilots do not have them (poor sensitivity) and a lot of non-pilots have them from contact with cockpit structures during crashes (poor specificity). Les Folio addressed this in one of his articles out of the AFIP. I can send you a copy of you like. Basically unless you have a black box or the hand is clenched in cadaveric spasm around the controls, there does not appear to be a reliable indicator as to who was in control.

Just asking. I was told in the class room that whoever's cadaver had the highest CO2 level was likely the one on the controls at the time of impact. The FAA guys in the room agreed. Could this be another urban legend? The bone injuries were also covered as indicators.

Bob