Instrument sources, scanning and failure interpretation
Instrument teaching begins with the source of each indication. A conventional airspeed indicator compares pitot and static pressure, an altimeter responds to static pressure and a vertical-speed indicator interprets pressure change through its mechanism. They share information sources but do not respond identically to every blockage. Specify the inlet, drain and static-port condition before predicting a result; saying only that the pitot tube is blocked leaves an important ambiguity.
Separate failure cases
When ram air is blocked while an open drain vents the pitot line, the pressure behavior differs from a fully sealed pitot line. With both inlet and drain blocked and the static source available, trapped pitot pressure can produce an apparent airspeed increase during a climb. This is not evidence that every blocked inlet makes the indicator behave like an altimeter. A blocked static source can freeze a conventional altimeter near the indication at blockage while also distorting other instruments using that source.
An alternate static source may use cabin pressure in an unpressurized installation. The actual correction and effects depend on the installation. The usual lower cabin pressure can produce a higher indicated altitude and airspeed and a transient vertical-speed change; the aircraft documentation remains the authority for its use and corrections. Do not reverse the altitude effect merely because the word alternate suggests a lower reading.
Gyros and electronic displays
Gyroscopic attitude and heading systems can have vacuum, electrical or other designed sources. Do not assert that every modern display uses a vacuum pump. A failure can develop gradually, and a convincing attitude display is not independently validated by the learner's confidence. Identify which indications share sensors, power or data before treating two agreeing displays as independent confirmation.
Teach relationships and control
An attitude-instrument scan links attitude, power and performance rather than staring at one indication. A primary-and-supporting model and a control-and-performance model organize attention differently, but both require interpretation of the actual maneuver and consistent supporting evidence. An altimeter is not the primary pitch-performance instrument for every maneuver simply because it measures height.
Use a bounded ground scenario to ask what remains reliable, what conflicts and what additional evidence is needed. Physical sensations without a useful visual horizon can be misleading; this does not make a failed instrument trustworthy. Actual unusual-attitude recovery, equipment operation and emergency actions require the approved aircraft guidance and qualified practical instruction, not an unqualified sequence memorized from an isolated practice question.