Weight and balance considerations
Handheld calculators lay to rest mathematical terrors so common to early days of student aviating--at least, according to some. Your local examiner probably has a few humorous stories about nervous applicants who couldn't get their modern-day abacus to work. At some point, said aviation hopefuls pulled out of some rumpled flight bag a far older technology with which to prove that the airplane was in fact not only within weight limits, but also within balance limits. I certainly have. Have you?
Although it might seem obvious, some private pilot applicants seem shocked to learn at the last moment that they must actually determine a weight and balance for their individual airplane during their practical tests. There are many reasons that what many consider a life-and-death issue becomes a mere detail, routinely overlooked during the course of flight training. These reasons (excuses, you say) range from student/instructor duos always flying the same airplane, with the same fuel load, thus complacency strikes--to the occasional students whose backgrounds lead them to prefer a quadruple wisdom-tooth extraction over facing the mathematical music inherent in weight and balance calculations. Yes, I admit to having been in that latter category. Needlessly so, it turns out.
As you prepare for your (or your student's) upcoming day with a DPE, there are some things you should know about what is fair game in this area during testing. The two basic facts are:
- Anything from the references listed in the practical test standards is fair game.
- Most (not all) DPEs are simply satisfied with the weight and balance for the airplane being flown for that checkride, and
- If an applicant displays or even hints at any weakness in knowledge about the vital importance of weight and balance to safe flight, there will most likely come deeper questioning.
What? That was three, and I said two? I lied!
Some people love working with numbers, and often these are virtuosos in calculating weight and balance using the computation method. One applicant was so numeral-enamored that he performed weight and balance figures mentally. Yes, he was correct in his findings--in every scenario. He finally lowered himself to my humble level, took pencil and paper in hand, and patiently explained every detail of how a real pilot predicts an airplane's performance for the impending flight.
Understand, however, that neither you (nor your student if your are the instructor) must demonstrate such an algebraic addiction. You need not demonstrate a mastery of numbers at all. Simply determine the weight and balance, which may include graph or table methods as well.
Because manufacturers also recognize the algebra allergy inherent in some of us, many graciously provide tables and graphs that have done the digit dirty work already. We simply need to understand how to use these. Naturally, we must understand the principles behind weight and balance before we can use tables and graphs with skill, or with comprehension beyond the mere rote repetition of a voice recorder. It is at this point that some pilot examiners see things fall apart.
Doing the weight and balance computations and chart or graph work is one thing, but explaining what happens if weight is excessive, or if balance is out of the limits, can be something else. Be prepared (or prepare your student) for friendly, chitchat queries about what if the airplane is overweight. Every pilot must know that higher takeoff and approach/landing speeds go hand in hand with overweight airplanes. Longer takeoff and landing rolls than the handbooks predict are also common.
There are other bad things that plague an overweight flying machine, but two of the most critical are higher stalling speeds and excessive stress on the landing gear during landings. If ever there was a reason for student pilots not to believe that they will experience everything they need to know with their flight instructors, this is one!
Adverse balance is even worse. Because an airplane's flight characteristics change in ways similar to those brought on by excess weight, sometimes students do not have a clear appreciation for the out-of-balance situation's cold threat. Stability and control become the key targets when an airplane's center of gravity wanders outside the fences that define its pasture.
The Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25) provides an accurate if not particularly exciting discussion of what a pilot can expect. You should read this not only for your upcoming checkride, but also for your flying career beyond testing day. It is not just your personal safety at stake! Flight instructors serve their students, the aviation community, and the general public very well when they insist that their students perform an actual weight and balance computation before every flight. Actual, in this case, means that variables occur such as hypothetically tossing on board a box of Florida oranges, or California avocados, or--all right, for once I'll refrain from bringing up a product from my beloved Nebraska. Let your imagination rule!
By varying the specified loading for successive flights, students avoid the complacency that comes with familiarity. This practice has the added benefit of preparing students for the inevitable changes in weight, balance, and loading. Weight shifting, as well as adding and removing weight, are aspects of airplane performance that are reasonable for private pilots to master. Interestingly, it is one of the few skills that an FAA publication--the Pilot's Handbook of Aeronautical Knowledge--says that pilots must be able to accurately and rapidly solve.
The formula again is simple; Weight Shifted over Total Weight equals Change of CG over Distance Weight is Shifted, so pencil-and-paper determinations are easy enough, but using handheld calculators or electronic flight computers makes the task a breeze.
Again, it is likely that most pilot examiners will not dive so deeply into this aspect of weight and balance, but it is possible.
Speculations and ramblings aside, your objective as a student pilot is safety--just as it will be as a private pilot, or an instrument pilot, or a commercial pilot, or an airline transport pilot. Just keep your dream out of the fields occupied by raging bulls.
Dave Wilkerson is a designated pilot examiner, writer/photographer, and historian. He has been a certificated flight instructor since 1981 with approximately 2,000 hours of dual instruction, and is a single- and multiengine commercial-rated pilot.
Related Articles
