Unicom

September 2000 Issue




Twice as Nice

The “Twice Bitten” article was good [Proficiency, July], but I remain curious about the accident statistics on twins. Fatalities, per the stats, are four times as high for a twin when an engine fails than for a single as you noted. Not hard to understand during takeoffs. But how do the stats include the numerous instances of engine failure in a twin that never make it into the database because the plane landed without incident?

My own admittedly limited database contains many instances. When an engine fails during cruise and landing phases of flight, I bet more singles don’t land safely. What should I draw from the stats? Is my sense of “twin security” while flying over water and at night false?

-Michael Grasley
Via e-mail


One thing we didn’t make clear in recounting the study was that it covered engine failures that resulted in an accident, not all engine failures. Many twins land safely on one engine, just as many singles deadstick in to a fate that doesn’t meet the NTSB’s criteria to be called an accident, either. It’s anyone’s guess just how many that is. Although such studies help put some perspective on risk, don’t let them make your decisions for you. Remember what Mark Twain said on the matter of statistics.

As for your sense of security, consider the fact that the vast majority of accident causes have nothing to do with sudden mechanical problems in the engine(s). You may or may not be safer in a twin. It depends on where you fly, how you fly, and how you make decisions related to flying.

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Weighty Issue
I thought “Twice Bitten” [Proficiency, July] was an excellent article but would like to point out what I believe to be a small error. Mr. Leis states that “In addition, actual Vmc decreases with increased altitude and decreased aircraft weight.” In fact, Vmc increases with decreased aircraft weight. Although high gross weight decreases climb performance, it improves controllability in so far as Vmc is concerned.

-John L. Worling
Via e-mail


Mr. Leis replies: According to the FAA Flight Training handbook, “An increase in the airplane’s gross weight may be expected to have an adverse effect on stability, regardless of location of the center of gravity. The stability of many certificated airplanes is completely unsatisfactory as the gross weight is exceeded.”

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Vmc is What You Make It
Raymond Leis’ article on multi training and safety was informative and covered a lot of ground [Proficiency, July]. In the sidebar “Counter Fit”, he builds an excellent case for the left engine being the “critical” one on a twin where both engines turn the same way. Having only the right engine operative is the most adverse situation; thus, the left one is critical, since its loss has the most impact.

I’ve been a multi instructor for some years and teach in Hawaii. Because of our above-standard temperatures, much of the time density altitude will put Vmc below stall and I limit the student’s rudder with my feet to simulate Vmc at a higher airspeed.

This does two things: It helps avoid the trauma of a single engine stall and it also teaches the student to recognize loss of directional control rather than fix on the airspeed indicator while he or she waits for the magic red radial. I also teach that there is no such thing as a single-engine go-around in a light twin and it is a pity that so many light twin AFM’s suggest that a single-engine go-around is an acceptable maneuver.

Once the power on the operating engine has been reduced significantly on the approach and the aircraft is configured to land, the go-around/missed approach is an extremely risky maneuver in an aircraft that may have a 200 fpm climb at sea level with one engine feathered and flaps and gear retracted. I would rather the pilot recognize that at some point on the approach he or she is committed to land.

-Hank Bruckner
Honolulu, Hawaii

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Log That Inop Equipment
It seems to me that Chip Wright’s article “How Much is Enough” [Systems Check, July] gives a fine description of the philosophy of “deferring” inoperative items. However the article also gives the impression that no further action is required to “defer” when operating under Part 91. FAR 91.213 is quite explicit in requiring the item to be removed or deactivated and placarded with appropriate entries made in the maintenance records as per Part 43.

-Jaime Alexander
Council Bluffs, Iowa


It’s true that FAR 91.213(d)(3) requires further action, but we’d be willing to bet that half the airplanes on our local ramp don’t meet the letter of that regulation – just check out the number of squawks on any prebuy inspection sheet. The paperwork is what it is. We figure most readers have already realized that anything other than washing the airplane needs to have a paper trail.

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I’m Not Dead Yet, Part I
I just read “The Death of Airmanship” [Commentary, July]. I can scarcely describe the resonant chord that it struck in me. I have been involved in general aviation safety for over a quarter of a century, first as the owner and chief flight instructor of a flight school, and then as an underwriter for Avemco. I, too, have been deeply concerned with the deterioration in basic airmanship that I have observed during that time.

While some would debate the causes of this lack of basic airmanship, I think you covered them well in your commentary. Money and technology do indeed often work against the exercise of airmanship. You are also exactly on target when you state “... there’s a more insidious problem eroding the safety of GA flying – the reluctance of pilots to take responsibility for their own safety.” I see the tragic consequences of this reluctance every day.

Finally, your suggestions for improving airmanship are also on target. Our loss records support your points with almost mathematical precision. If everyone would follow your recommendations, the accident rate would be reduced dramatically. If that lower rate resulted in fewer claim payments (a strong likelihood), the impact on insurance premiums would also be significant. Thank you for your insightful column. I hope that it is widely read and distributed.

-Jim Lauerman
Via e-mail


Editor’s note: Lauerman is executive vice president of Avemco Insurance Co.

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I’m Not Dead Yet, Part II
I emphatically agree with “The Death of Airmanship” [Commentary, July]. My experience so far as a part time instructor has mainly consisted of BFRs, and airplane checkouts for pilots who haven’t flown in a while or are stepping up to a new plane.

I am amazed at the lax approach that all but a rare minority display. After the initial run up, the published checklist is permanently stowed, and the airplane is flown like a blonde driving a Lexus doing her make-up. There is no well-ingrained procedure for engine failure, go arounds, or even simple pattern procedures and target airspeeds.

Your comments about financially successful pilots buying more airplane than they have the discipline to maintain proficiency in is, in my opinion, the reason physicians have such a poor reputation for safety.

To be concise, pilots need to fly with a highly systematic and regimented approach. At times this seems to take away some of the freedom that originally attracted us to the avocation, but anything less makes the pilot more likely to create his own emergency and less likely to be able to deal with it. A deadly combination.

I recommend to students to have fun at striving for perfection in all tasks, whether it is taxiing smartly on the center line or nailing airspeed on final and coming to a full stop in the specified distance. If you are not in the process of obtaining a new rating or endorsement, I recommend getting a half day or so of dual every six months from an instructor you have never flown with. The cumulative knowledge from this can be impressive.

Also, fly regularly, or don’t fly at all. Since I first discovered your publication in 1994 I have read every issue cover to cover and have used it to modify my own system of checklists and procedures. No doubt it has made my students and me vastly safer pilots.

-Frank Del Vecchio
Via e-mail


Good thing you didn’t say “like a blonde driving a BMW doing her makeup,” or my wife may have taken offense. Seriously, we can find no fault with your logic, but figure we’d run out of instructors pretty quickly – at least, instructors we’d want to fly with.

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Student Sword Swallower
I felt a need to respond to “Gag Reflex” [Editor’s Log, July]. Most of us share your squirmy feeling, maybe rooted in our own misgivings about our own misdeeds (in the past, of course), when confronted by such perfectionistic behavior.

But seriously, who would you rather have sitting up front when you are depending on him to get you there in the DC 10 or whatever? Well, if it’s good enough then, why not you too?

Seems like it’s hard to have too much professionalism in any activity in which you put your life on the line. Yet, I tend to wonder why your pilot friend doesn’t a) move up through Commercial, to ATP (they have that for single engine, too), and b) get his CFI and let us start seeing more really safe pilots in GA.

And for your nausea, my advice as a physician is: Go for it. With enough practice, you’ll probably become a sword swallower.

-R.C.Thompson
Via e-mail

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Is That the Best You Can Suggest?
For years, I have been reading articles similar to “Avoiding a Belly Slide” [Risk Management, June] that urge pilots to “do the checklist” and establish routine procedures. The unintentional gear-up landing rate doesn’t seem to have improved. I question whether the checklist and cockpit routine are sufficient solutions to the problem of gear-up landings.

Any safety system that is dependent on the actions of a single human being is designed to fail. Obviously, this statement puts the whole state of general aviation safety in jeopardy as most of it is conducted single-pilot. But within GA operations, specific tasks – like extending and retracting the landing gear – can be evaluated as systems and provided with other safety barriers that are not human-dependent.

It is a classic error in general aviation safety that we do not routinely take a systems approach. The message to general aviation pilots in various safety media is simply “try harder.”

In commercial operations in highly standardized cockpits, I have seen entire checklists missed or important items like gear and flaps skipped by pilots who are neither careless nor reckless. But, in a Boeing, there are five barriers other than the pilot in command that would warn of an impending gear up landing. In many cases, simple systems are available for most retractable gear aircraft.

The flap actuated gear warning in my PA-30 cost less than $200. These systems are simply not being installed. I blame this at least partially on a pilot-centric safety message. We need good checklist habits and normal procedures in general aviation as you have discussed, but we also need to step back and examine systems and design barriers for those costly and senseless errors like inadvertent gear ups.

-Chris Burns
Via e-mail


We agree in principle that there are many design improvements that can make GA safer, but practical execution of all of them is impossible. Taken to extremes (and who’s to say where that extreme is?) we’d all be flying airplanes with space shuttle-like redundancy. But who can afford that? Plus, putting in place the hardware to monitor everything (including failure modes) would add weight and complexity to airplanes that can scarcely handle more.

Good hardware can make a big difference if applied judiciously, but it’s far from a cure-all.

The whole matter of inadvertent gear-ups, frankly, has us a bit mystified. An airplane zipping down final with the gear tucked away just doesn’t look right, feel right, sound right or fly right. Maybe if you’re just transitioning into the airplane you wouldn’t notice, but if you’ve been flying it for years …