FLYING LESSONS for January 2, 2014 suggested by this week s aircraft mishap reports FLYING LESSONS uses the past week s mishap reports to consider what might have contributed to accidents, so you can make better decisions if you face similar circumstances. In almost all cases design characteristics of a specific make and model airplane have little direct bearing on the possible causes of aircraft accidents, so apply these FLYING LESSONS to any airplane you fly. Verify all technical information before applying it to your aircraft or operation, with manufacturers data and recommendations taking precedence. You are pilot in command, and are ultimately responsible for the decisions you make. FLYING LESSONS is an independent product of MASTERY FLIGHT TRAINING, INC. www.mastery-flight-training.com Share safer skies. Forward FLYING LESSONS to a friend. This week s lessons: A reader wrote me over the holiday: I went through the [Pilot s Operating Handbook] for my 1985 [Beech Bonanza] F33A to create a table of airspeeds to be used as a reference [which the reader attached to his email]. My intent is to make it a decal to stick on the yoke. I believe I did all of the calculations correctly for my aircraft, but cannot find anywhere to validate them. Have you done calculations like these before? The pilot s tables listed book airspeed numbers when applicable, and computed figures when the POH provides no specific guidance. In typical light airplanes, most performance and airframe safety speeds decrease at the rate of roughly 1% for each 2% reduction in airplane weight below the certificated maximum gross weight. I replied: Your numbers are consistent with those I came up with for mid-80s F33As while I was running Bonanza pilot training at Beech Field in the early 1990s. A few comments: 1. The V A figure [design maneuvering speed, also the turbulent air penetration speed] is more important than most pilots realize. A critical but almost never-discussed concept: we need to slow to V A when we suspect the possibility of turbulence. V A speed provides protection against overstressing the airplane in turbulence, but we do not get a "free bump" before we have to slow down. In other words, the first moderate to severe bump can over stress the airplane, so we can't wait until we actually encounter the turbulence to start thinking about slowing to a weight-adjusted V A. We must use knowledge of weather and active weather and PIREP monitoring to slow to V A before the first severe turbulence encounter. 2. Another critical by rarely mentioned consideration: turbulence encounters will result in airspeed variations, both upward and downward. To protect against airframe overstress, you must fly at an airspeed such that the highest airspeed excursion is still below V A as adjusted for the airplane's weight. It's common to see airspeed variations of 10 to 15 knots in a Bonanza-class airplane at low cruise (near V A ) airspeeds. Therefore, computed V A is NOT your target speed. It's the NEW AIRSPEED REDLINE. If you anticipate encountering turbulence strong enough that you must slow to V A, you must actually slow to 10 to 15 knots below the computed V A, so that you do not exceed V A in the airspeed excursions. 3. Practice the power settings and configurations that result in your target airspeeds in level flight, and commit those conditions to memory. Putting retractable landing gear down is an excellent idea; it helps slow the airplane, but also by moving the center of gravity forward in many designs (nose wheel swinging out) and downward, and also by introducing three additional fixed vertical stabilizers (the gear legs) into the airstream, you greatly increase the airplane's stability in turbulence. Further, the additional drag of extended gear resists acceleration in bumps and if turbulence pushes you into a downward attitude.
Renowned aviation educator (and FLYING LESSONS reader) Rod Machado wrote what I think is the very best explanation ever of the relationship between airplane weight and V A, expressed in the context of changing angles of attack (AoA) for given phases of flight at different weights. See http://flighttraining.aopa.org/magazine/1999/march/199903_flying_smart_a_new_look_at_maneuvering_speed.html I also addressed the pilot s tabulated figures for weight-adjusted takeoff and landing speeds, which in this case came directly from POH sources. 4. With a type-knowledgeable CFI, practice slow flight, approach to landing stalls, power in stalls and accelerated stalls at a safe altitude until you are very familiar with the feel if the airplane and its control requirements at high angles of attack. Then, still with the instructor, practice (still at a safe altitude) the landing and takeoff profiles using the speeds you've derived for your Bonanza. Only then, return to the airport and practice takeoffs and landings actually using those speeds. Most pilots, in my experience, fly at much faster airspeeds (lower angles of attack) than the "book" or derived numbers. Pilots that have had stall-related accidents may have been trying the numbers for the first time, while under the very real pressures of seeing the tree line coming up fast, or the runway threshold shrinking because the target speed results in a higher rate if descent that they're used to. For example, the Beech F33A POH calls for a 900 feet per minute rate of descent at the tabulated 50-foot [ over the fence ) speed in the Associated Conditions of the Landing Performance chart. Most pilots would be sorely tempted to pull back on the controls seeing the ground come up so fast unless they are familiar with the profile increasing angle of attack and sink rate, with a trend toward stalling the airplane. It takes practice to do it right. Waiting until needing maximum performance for real isn t a good success (or survival) strategy. A false sense that the airplane can attain a certain takeoff or landing performance without actually flying the proper speeds is equally inefficient in resulting in success. Comments? Mastery.flight.training@cox.net Debrief: Readers write about recent FLYING LESSONS: Reader Mike Busch writes about last issue s LESSONS derived from my recent attitude indicator failure experience: Tom, that's an interesting and unusual AI failure you encountered over the T-day weekend. In my experience, air-driven gyros seldom fail in-flight unless the failure is caused by loss of vacuum/pressure. The usual failure mode of the gyro itself involves contamination of the bearings (either spindle or gimbal bearings) or contamination of the pendulous erecting vanes, and those failure modes typically show up at engine start when the gyro fails to spin up or erect properly. If the gyro spins up and erects normally, then in my experience it usually operates properly for the duration of the flight. It will be interesting to find out the details of what caused your AI failure. I'm wondering if perhaps an air hose or connection failed, as opposed to a failure of the gyro capsule itself. Please keep us posted. See www.mastery-flight-training.com/20131219flying-lessons.pdf I suspected a loose hose connection as well, which is why I tried the back-up instrument air pressure pump even though system knowledge told me it should have no effect. Of course as I wrote last time it did not help. Our flying club director of maintenance, who is also a mechanic instructor for an international flight safety corporation, tells me the indicator failed [from] excessive friction in the bearings internally. He tells me he s learned from fleet operators that this is fairly common in the Honeywell/Bendix-King AIs employed in KFC150/225 autopilot/flight director installations. Good to know. Mike continues: I've found that it's a good habit to watch an air-driven AI carefully at engine start, and to listen to it carefully
after engine shutdown. An air-driven AI whose gimbal bearings are starting to fail will not "nutate" normally during startup, and one whose spindle bearings are starting to fail will sound noisy and nasty when spinning down. An air-driven AI with a sticky erection vane will typically go "hard over" upon engine start, although you might be able to get it to erect properly (one more time) either by increasing RPM (and thereby airflow) or by shutting down the engine, letting the gyro spin down fully, and then restarting. When you start to notice one of these warning signs, it's good to send the gyro out for repair or overhaul sooner rather than later. These things always get worse (usually rapidly) and then never cure themselves. Also, if such contamination-induced gyro failure seem to be recurring with inordinate frequency, the cause may be old air hoses that are starting to come apart inside and shedding shards of rubber into the instrument. The pneumatic system's filters do not protect air-driven gyros from contaminants originating from the hoses themselves. Excellent advice, Mike. Discrepancies don t repair themselves although indications may sometimes go into remission, only to return at the worst possible times. More from Mike: Last June, I experienced an autopilot failure [in a Cessna T310R twin] in the middle of a 45-day 6,500-nm trip that caused me to have to do more actual hand-flying in 10 days than I'd done in the previous 10 years. It was definitely a character-building experience. Fortunately, it occurred only days after I completed a 3-day recurrent training cycle in the sim (where all the flying was hand-flying and the sim was a lot less stable than the actual airplane), so at least the timing was optimal. Many times I ve heard pilots who have successfully dealt with inflight systems failures tell me they credit training they had received shortly before the actual failure event. Whether this means we should all train more frequently, or that pilots who train more frequently are better prepared, is irrelevant either way it suggests training far beyond the minimum required by regulatory authorities is a potential lifesaver. Good job, Mike, and thanks again. Reader Dave Van Horn continues: Good advice as always, Tom. One refinement: if you can't stay VMC, make your time in IMC as easy as possible. Give yourself every advantage. The first time I lost the AI in IFR I was between layers. I worked hard to stay that way the rest of the flight, requesting frequent altitude changes, while I practiced my partial panel skills. Finally, there was nothing left but the ILS and by that time I was feeling pretty comfortable partial panel. That's when I screwed up. ATC gave me a descent into IMC, then a vector to intercept the localizer. Those partial panel turns to intercept in IMC were much more challenging than I expected. I should have stuck with my first thought, which was to "unable" the descent into IMC and ask to be vectored to intercept the localizer at my between-layers altitude, however many miles out of the way that was. Then I would have done the turn and intercept in VMC and been on the ILS and stabilized, with nothing left but following the needles, before entering IMC. It would have taken longer to get it on the ground but it would have been a very worthwhile tradeoff. Indeed it would. Excellent advice yourself, Dave! Frequent Debriefer Tom Allen adds: Since owning my plane: three air pumps [have failed], one in IMC, and [my] AI [failed] while climbing out through a 300-foot ceiling. The AI checked OK in the preflight but froze right after liftoff and then started working again about one hour later. More evidence that points to the need for regular review of partial panel skills in a realistic training environment. Reader Bill Caton asks a decision-making question: If [you were] IFR I am thinking you would have diverted on a heading to the closest VFR weather? Correct, per item #9 of my partial panel checklist: 9. If you re in IMC, aim for VMC. Again, don t be a hero. Aim for clear skies. Reader Don Lawton is thinking: Thanks again for another thought-provoking issue of FLYING LESSONS Weekly. One statement got me thinking: "The airplane was trimmed for level flight before the AI failed, so it was still trimmed after..." In the case of an AI (or AH - I'm a vintage pilot) with a more subtle loss of function, is it possible that the autopilot may have tried to trim for what was no longer level flight while following the failing AI? The takeaway being the pilot might expect an out of trim condition when taking over from the AP. True, Don. I hinted at that in item #1 of my checklist:
1. Maintain control of the airplane. Do not retrim unless you (or the autopilot) was retrimming at the time the failure occurred. Keep the trim set until you need to change it with a change in flight conditions. Use very light control inputs and limit use of the ailerons. but you re correct in making the trim issue more completely understood. Thank you. Reader Alan Davis is back with this comment: Great piece on instrument failure, and your checklist is a good one. In doing a lot of [FAA] Wings [refresher] flying refresher stuff with instrument rated pilots, I have found that item #7 - Known combinations of power, flaps and gear along with pitch attitude - is one of the weaker areas. In fact, I can't tell you how many times folks come charging up on the marker with nothing done in preparation for an approach. Since we are doing proficiency work, I let them do it the first time, which usually results in a far less than satisfactory approach. Then we go out of the area to talk about it, and practice some pitch, power, configuration, and attitude work - including slowing to approach speed and getting out the first notch of flaps. They are usually amazed at the stability that results and then remember that that is the way they learned it - they had just forgotten. So, stable flight in various regimes, not just for approach, along with speed and configuration changes, are well worth the effort as part of the "prep" for the possible instrument failure as well as a good approach with or without an instrument, since stability of flight is the saving grace! Thanks for spreading the word with your expert instruction, Alan. Thanks to my friends at AVEMCO Insurance for three years of sponsoring FLYING LESSONS Weekly, which ended with 2013. This help has been instrumental in paying the bills to bring FLYING LESSONS to thousands of readers each week. If you have an aviation-related product or service you d like to highlight while at the same time showing your corporate support for pilot education to enhance aviation safety, please contact mastery.flight.training@cox.net for sponsorship information. Family and friends who have been my passengers have greatly benefitted from your experience and wisdom over 20+ years. Thanks for all you have done for us and continue to do. It is amazing how much the training you provided is top of mind for me on every flight. FLYING LESSONS continues the learning and keeps me freshened up! I hope you can keep it up for years to come. It is apparent it's a huge time and brain user. Alan Bassani It costs a great deal to host FLYING LESSONS Weekly. Reader donations help cover the expense of keeping FLYING LESSONS online. Be a FLYING LESSONS supporter through the secure PayPal donations button at www.mastery-flight-training.com. Why We Cancel Flights Thank you, generous supporters I ll soon return to the promised discussion of days to reduce as much as possible the number of flights that must be delayed, rescheduled or canceled, to get the most utility out of cross-country aircraft while keeping risk mitigation and safety as the primary goal it needs to be. I have some very concrete suggestions to attain this goal, but before we begin I invite FLYING LESSONS readers to help me make certain I have the topics covered. Here are the main reasons general aviation flights are delayed, rescheduled or canceled. Do you have comments or additions? Please let me know so that I may consider your input before starting the real discussion. REASONS FLIGHTS ARE DELAYED, RESCHEDULED OR CANCELED 1. Adverse weather 2. Aircraft maintenance issues 3. Pilot factors 1: Health, fatigue 4. Pilot factors 2: Certification, currency 5. Airspace issues: Temporary Flight Restrictions (TFRs), other airspace inaccessible to general aviation or available only with special authorization or requirements
Did I miss anything? Please let me know, at mastery.flight.training@cox.net so we can get to work on maximizing the safe utilization of our airplanes. Thanks! More NTSB Safety Alerts The National Transportation Safety Board has issued five new Safety Alerts that provide general aviation (GA) pilots with mitigating strategies for preventing accidents. These Safety Alerts follow five that were issued in March that focused on the most frequent types of general aviation accidents. Knowing these accidents, which sometimes include entire families, can be prevented is why General Aviation Safety is on our Most Wanted List of transportation safety improvements, said NTSB Chairman Deborah A.P. Hersman. These five [new] Safety Alerts remind pilots, mechanics and passengers of basic safety precautions to add to their checklists to ensure a safe flight for all on board. The new NTSB Safety Alerts are: Check Your Restraints Engine Power Loss Due to Carburetor Icing Armed for Safety: Emergency Locator Transmitters All Secure, All Clear (securing items in the aircraft cabin) Proper Use of Fiber or Nylon Self-Locking Nuts The new GA Safety Alerts, as well as 25 others issued since 2004 (including five video Safety Alerts), are available at http://go.usa.gov/2bea. Happy New Year, everyone! Share safer skies. Forward FLYING LESSONS to a friend. Personal Aviation: Freedom. Choices. Responsibility. Thomas P. Turner, M.S. Aviation Safety, MCFI 2010 National FAA Safety Team Representative of the Year 2008 FAA Central Region CFI of the Year FLYING LESSONS is 2014 Mastery Flight Training, Inc. Copyright holder provides permission for FLYING LESSONS to be posted on FAASafety.gov. For more information see www.mastery-flight-training.com, or contact mastery.flight.training@cox.net or your FAASTeam representative.