PLT216: Total Energy Compensated Variometer
What code PLT216 covers, why the FAA tests it, and how to study Total Energy Compensated Variometer before your checkride.
Recall flight instruments - total energy compensators
What this means for your checkride
An uncompensated variometer indicates rising or descending air accurately only when the pilot holds a constant airspeed, because a pull-up or pushover changes pressure altitude and produces false climb or dive readings known as stick thermals. A variometer with a total energy system senses those airspeed changes and cancels most of the stick-thermal effect, so the pilot sees air mass movement despite changing airspeed. Common designs use a venturi, a slot, or a total energy probe placed in undisturbed airflow and connected to the static side of the variometer, or a diaphragm compensator plumbed in from the pitot line.
Pilots must understand why a compensated variometer reads air mass movement more reliably than an uncompensated one during pull-ups and pushovers.
Total energy compensation does not subtract the glider's own sink to show pure air mass movement; that is the job of a Netto system. Compensation only removes the error caused by airspeed changes.
Where to study it
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.