✈️ Aviation Brief — Issue #77
Weekly insights for student pilots and the instructors who train them.
THIS WEEK'S TOPIC
CA.II.C — Flight Instruments (Commercial Pilot ACS)
1. ACS STANDARDS SUMMARY
The examiner expects the commercial applicant to explain the pitot-static, vacuum/pressure, and gyroscopic systems and how they drive each flight instrument. The pilot must identify instrument errors caused by blockage, leakage, or failure; interpret what each instrument will do during those failures; and describe proper corrective action or cross-check techniques. The applicant must also explain compass errors (northerly turning, acceleration, magnetic dip) and demonstrate how to use the instruments as a reliable cross-check during normal and emergency operations.
2. THREE COMMON STUDENT MISTAKES
- Mixing up the effects of a blocked pitot tube versus a blocked static port on the airspeed indicator, often stating the ASI will read zero when only the static port is blocked.
- Describing gyroscopic precession as “the opposite direction of the applied force” instead of explaining the actual 90° reaction that occurs later.
- Believing the magnetic compass will show an immediate and accurate turn when rolling out on a northerly heading, instead of anticipating a lag of up to 30°.
3. CFI PRO TIP
Have the student cover the attitude indicator and fly a short pattern or basic maneuvers using only the remaining five instruments; this forces them to actually watch the altimeter, VSI, and turn coordinator for trends rather than fixating on the artificial horizon.
4. SAFETY SPOTLIGHT
NTSB reports and ASRS submissions continue to show incidents in which pilots misidentify a static-port blockage during descent and chase an erroneous altimeter and VSI, resulting in controlled flight into terrain or near-miss altitude deviations. The 1997 Beechcraft Baron accident near Grand Junction is one documented case where a blocked static port produced a 400-foot altimeter error that went unrecognized until late in the approach.
5. DID YOU KNOW
The pitot-static system on your training aircraft must be inspected and certified every 24 calendar months under FAR 91.411, even if the airplane is only used for VFR training.
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