How does the pitot-static system work?
The pitot tube senses total pressure; static ports sense ambient pressure.
- ASI uses both
- Altimeter and VSI use static only
DGCA Technical General · 35 questions
Pitot Statics: DGCA Technical General Questions and Answers
35 practice questions on Pitot Statics with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.
About this topic
Use this page to revise Pitot Statics for the DGCA Technical General paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 35 questions in the TrueHeading bank for this topic.
In short: The pitot tube senses total pressure; static ports sense ambient pressure.
Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.
Key concepts: Pitot Statics
5 ideas to know cold.
What happens if the pitot tube blocks?
ASI reads zero (drain open) or acts like an altimeter (drain blocked too): reading rises in a climb.
What if the static source blocks?
The altimeter freezes, the VSI reads zero, and the ASI is wrong in a climb or descent.
- ASI under-reads in a climb and over-reads in a descent
- An alternate static source in the cabin makes the instruments read slightly high (altimeter high, ASI high, VSI shows a momentary climb)
What does each pitot-static instrument use?
ASI: pitot and static. Altimeter: static. VSI: static. Mach meter: pitot and static.
- Blocked pitot with drain open: ASI reads zero
- Blocked static: altimeter frozen, VSI zero, ASI error
- Alternate static source: cabin pressure
Tip: ASI: both. Altimeter and VSI: static only.
How do pitot-static errors affect the instruments?
Position error (source location), instrument error, lag, and temperature/density effects.
- Position error varies with attitude and configuration
- Compressibility error: ASI over-reads at high speed
- Density error corrected for TAS
Practice questions: Pitot Statics
Tap “Show answer” after you have tried each one.
Q1At sea level (ρ = 1.225 kg/m³) the dynamic pressure at 60 kt is approximately:
- 583 Pa
- 2205 Pa
- 1167 Pa
- 292 Pa
Show answer
Answer: A. 583 Pa
q = ½ρV² with V in m/s (1 kt = 0.5144 m/s).
Q2At sea level (ρ = 1.225 kg/m³) the dynamic pressure at 80 kt is approximately:
- 519 Pa
- 3920 Pa
- 1037 Pa
- 2075 Pa
Show answer
Answer: C. 1037 Pa
q = ½ρV² with V in m/s (1 kt = 0.5144 m/s).
Q3At sea level (ρ = 1.225 kg/m³) the dynamic pressure at 120 kt is approximately:
- 4668 Pa
- 1167 Pa
- 8820 Pa
- 2334 Pa
Show answer
Answer: D. 2334 Pa
q = ½ρV² with V in m/s (1 kt = 0.5144 m/s).
Q4At sea level (ρ = 1.225 kg/m³) the dynamic pressure at 200 kt is approximately:
- 6483 Pa
- 12966 Pa
- 24500 Pa
- 3241 Pa
Show answer
Answer: A. 6483 Pa
q = ½ρV² with V in m/s (1 kt = 0.5144 m/s).
Q5At sea level (ρ = 1.225 kg/m³) the dynamic pressure at 250 kt is approximately:
- 5065 Pa
- 38281 Pa
- 20259 Pa
- 10130 Pa
Show answer
Answer: D. 10130 Pa
q = ½ρV² with V in m/s (1 kt = 0.5144 m/s).
Q6The pitot-static system measures:
- density directly
- dynamic pressure only
- total (pitot) pressure and static pressure
- temperature only
Show answer
Answer: C. total (pitot) pressure and static pressure
Airspeed uses pitot minus static; altitude and VSI use static only.
Q7If the pitot tube is blocked (inlet and drain hole blocked) in a climb, the airspeed indicator:
- reads zero
- over-reads
- under-reads
- is unaffected
Show answer
Answer: B. over-reads
Trapped pressure stays constant while static pressure falls, so the indicated speed increases in a climb.
Q8If the pitot tube inlet is blocked but the drain hole is open, the airspeed indicator:
- reads zero (gradually decreases to zero)
- reads correctly
- over-reads
- freezes at the current value
Show answer
Answer: A. reads zero (gradually decreases to zero)
Pitot pressure leaks out through the drain, so the indicator falls to zero.
Q9The alternate static source in an unpressurised aircraft usually takes pressure from:
- outside at the wing tip
- the pitot head
- the engine
- inside the cabin
Show answer
Answer: D. inside the cabin
Cabin pressure is normally slightly lower than outside, so the altimeter reads a little high and the airspeed slightly high.
Q10Instrument error is caused by:
- the position of the static vent
- density changes
- manufacturing imperfections and friction in the instrument
- compressibility
Show answer
Answer: C. manufacturing imperfections and friction in the instrument
Applied via calibration cards.
Q11Pitot heating is provided to:
- prevent ice blocking the pitot head
- increase the pressure
- cool the pitot tube
- warm the cabin
Show answer
Answer: A. prevent ice blocking the pitot head
It must be checked before flight.
Q12ADC (Air Data Computer) receives inputs of:
- oil temperature and pressure
- static pressure, total pressure and total air temperature
- GPS position only
- fuel flow and fuel quantity
Show answer
Answer: B. static pressure, total pressure and total air temperature
It computes altitude, CAS, Mach, TAS and VS.
More DGCA Technical General topics
Aerodynamics & Performance181 QFlight Controls & Stability38 QAirframe & Structures25 QPowerplant79 QPropellers32 QAircraft Systems116 QBarometric Altimeters61 QRadio Altimeters37 QVertical Speed Indicators (VSI)32 QAirspeed Indicators24 QAirspeeds41 QMach55 QGyroscope52 QAttitude Indicators20 QTurn and Slip50 QINS, IRS and FMS32 QEFIS24 QAutoflight23 QFlight Director21 QEICAS / ECAM24 QEngine Instruments29 QTemperature Indicators34 QFuel Systems35 QCompass54 QWarning & Recording Systems33 QTCAS39 Q
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