INSTRU Genuine mistakes I am making With Exam Questions
And Correct Answers With Rationales.
INSTRUMENTATION – GENUINE ATPL MISTAKES
Questions 1–25
Question 1
A blocked pitot tube (drain hole open) will cause the ASI to:
A. Read zero
B. Over-read in climb
C. Under-read in descent
D. Behave like an altimeter
Correct Answer: D
Rationale:
With pitot pressure trapped and static changing, the ASI behaves like an altimeter — a very common
exam trap.
Question 2
A blocked static port will cause the altimeter to:
A. Under-read in climb
B. Over-read in climb
C. Freeze completely
D. Read zero
Correct Answer: B
Rationale:
Static pressure remains higher → altimeter over-reads during climb.
Question 3
Which instrument is least affected by static system blockage?
A. VSI
B. Altimeter
, C. ASI
D. Turn coordinator
Correct Answer: D
Rationale:
The turn coordinator is gyroscopic, not pressure-based.
Question 4
The VSI operates on the principle of:
A. Differential pressure
B. Gyroscopic rigidity
C. Rate of pitot pressure change
D. Magnetic induction
Correct Answer: A
Rationale:
VSI compares instantaneous static pressure with delayed static pressure.
Question 5
A common VSI error during sudden level-off is:
A. Lag
B. Reverse indication
C. Over-reading
D. Precession
Correct Answer: B
Rationale:
The VSI briefly shows a descent when leveling off from climb — classic exam mistake.
Question 6
The attitude indicator’s rigidity in space is maintained by:
A. Precession
B. Pendulous vanes
C. Gyroscopic inertia
D. Magnetic field
Correct Answer: C
Rationale:
Gyroscopes resist changes due to rigidity in space.
And Correct Answers With Rationales.
INSTRUMENTATION – GENUINE ATPL MISTAKES
Questions 1–25
Question 1
A blocked pitot tube (drain hole open) will cause the ASI to:
A. Read zero
B. Over-read in climb
C. Under-read in descent
D. Behave like an altimeter
Correct Answer: D
Rationale:
With pitot pressure trapped and static changing, the ASI behaves like an altimeter — a very common
exam trap.
Question 2
A blocked static port will cause the altimeter to:
A. Under-read in climb
B. Over-read in climb
C. Freeze completely
D. Read zero
Correct Answer: B
Rationale:
Static pressure remains higher → altimeter over-reads during climb.
Question 3
Which instrument is least affected by static system blockage?
A. VSI
B. Altimeter
, C. ASI
D. Turn coordinator
Correct Answer: D
Rationale:
The turn coordinator is gyroscopic, not pressure-based.
Question 4
The VSI operates on the principle of:
A. Differential pressure
B. Gyroscopic rigidity
C. Rate of pitot pressure change
D. Magnetic induction
Correct Answer: A
Rationale:
VSI compares instantaneous static pressure with delayed static pressure.
Question 5
A common VSI error during sudden level-off is:
A. Lag
B. Reverse indication
C. Over-reading
D. Precession
Correct Answer: B
Rationale:
The VSI briefly shows a descent when leveling off from climb — classic exam mistake.
Question 6
The attitude indicator’s rigidity in space is maintained by:
A. Precession
B. Pendulous vanes
C. Gyroscopic inertia
D. Magnetic field
Correct Answer: C
Rationale:
Gyroscopes resist changes due to rigidity in space.
