VERTICAL SPEED INDICATOR - Dgca question bank for pilots

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#1. During a missed approach and go-around procedure the change of aircraft attitude plus raising of the landing gear and changing of flap settings can cause short term unpredictable errors in certain instruments. The instruments most likely to be affected in this case are:

the altimeter, artificial horizon and vertical speed indicator.

the airspeed indicator, machmeter and vertical speed indicator.

the machmeter, airspeed indicator, altimeter and vertical speed indicator

the vertical speed indicator, airspeed indicator and altimeter.

Altimeter
Vertical Speed Indicator (VSI)
Airspeed Indicator

These errors are often caused by transient pressure variations in the pitot-static system during rapid changes in configuration or flight dynamics.

#2. The vertical speed indicator indications may be in error for some seconds after starting or finishing a climb or descent. The error is a result of:

a combination of time lag and manoeuvre induced errors.

a combination of position error and manoeuvre induced errors.

manoeuvre induced errors only.

a combination of time lag and instrument error.

The vertical speed indicator (VSI) indications may be in error for some seconds after starting or finishing a climb or descent due to a combination of time lag and manoeuvre-induced errors.

Time Lag: The calibrated leak in the VSI causes a delay in responding to changes in static pressure, leading to temporary inaccuracies.
Manoeuvre-Induced Errors: Rapid changes in pitch, acceleration, or vertical movement during manoeuvres can affect the static pressure reading and momentarily distort VSI indications.

#3. The advantage of having the VSI dial presentation in logarithmic spacing rather than in linear spacing is that:

at low rates of climb or descent the pointer movement is much larger and so is more easily read.

readings are instantaneous.

a greater range of rates of climb and descent is shown.

the internal mechanism is simplified by deletion of the calibration choke.

The advantage of having the VSI dial presentation in logarithmic spacing rather than in linear spacing is that:

Greater sensitivity at lower rates of climb/descent: Logarithmic spacing allows for finer resolution near the zero mark, making it easier to interpret small changes in vertical speed accurately.
Compact representation of higher rates: Larger vertical speeds are compressed into a smaller range on the dial, providing a clear and uncluttered display.

#4. In the IVSI, lag error:

is overcome by feeding a sample of static pressure to the case and delaying it to the capsule.

is virtually overcome by using a special dashpot accelerometer assembly.

is overcome by the use of logarithmic presentation.

is only overcome when initiating a climb or descent.

#5. Because the VSI measures rates of change of static pressure and not actual values of static pressure, position error:

never affects VSI indications

may cause errors in the VSI during the take-off run.

may cause errors in VSI indications whenever airspeed is changed, if at the same time there is a change in position error.

may cause errors in VSI indications whenever airspeed is changed, even if there is no change in position error.

Lag in pressure changes: The VSI relies on pressure differentials, and rapid acceleration can cause a temporary mismatch in the static pressure readings.
Static port positioning: Incorrect or disturbed airflow around the static port during takeoff may introduce erroneous readings.

#6. When entering a steep turn, an IVSI is likely to show:

no change in altitude.

a slight climb.

a slight descent.

a slight descent at high airspeed only.

When entering a steep turn, an IVSI (Instantaneous Vertical Speed Indicator) is likely to show:

A brief climb: This is due to the sudden change in the aircraft’s flight path, which can cause a temporary pressure variation in the static system, leading to an erroneous indication of vertical speed.
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#7. If the static vent becomes blocked during a climb:

the VSI will stop at the rate of climb of the aircraft at the time of blockage.

the VSI will indicate a decreasing rate of climb.

the VSI will return to zero.

the VSI will indicate an increasing rate of climb

If the static vent becomes blocked during a climb, the Vertical Speed Indicator (VSI) will:

Indicate zero : Since the VSI relies on the difference in static pressure to measure vertical speed, a blocked static vent will prevent it from detecting any changes in pressure as the aircraft climbs. As a result, the VSI will either show zero (indicating no change in vertical speed) or hold the last recorded value, without reflecting the actual climb rate.

#8. In conditions of clear air turbulence:

the standard VSI is more sensitive.

the IVSI is more sensitive.

both types will react the same.

the vertical acceleration pump will not be affected.

he IVSI is more sensitive than a standard VSI and responds quickly to changes in altitude. In turbulent conditions, CAT can cause rapid changes in vertical speed, and the IVSI will likely show sudden fluctuations as it reacts to these brief altitude changes. These fluctuations may be momentary but could be more noticeable compared to a standard VSI due to the IVSI’s faster response time.

#9. Change of temperature as an aircraft climbs or descends:

will affect VSI readings whenever temperature lapse rate differs from standard conditions.

is compensated at the metering unit by means of a capillary and orifice

has no effect on the VSI as only static pressure is used in this instrument.

may be allowed for by use of tables or computer.

Capillary: This is a narrow tube through which air flows, and it helps control the rate of air movement to the instrument’s measuring element. It helps regulate pressure changes caused by temperature fluctuations.
Orifice: This is a small hole that restricts the flow of air, which is key in controlling pressure. It ensures that pressure changes are evenly distributed, preventing sudden changes that could lead to instrument error.

Together, the capillary and orifice compensate for temperature-induced pressure variations. When the temperature changes, the air density changes as well, which could cause discrepancies in altitude readings. These components help mitigate these errors, providing more accurate readings despite variations in temperature.

#10. Permissible limits of accuracy of the VSI are ……. when ……. within a temperature range of ……. and ……. outside this range.

+ 250 fpm, on the ground, -20°C to +50°C, + 300 fpm

+ 200 fpm, at any height, -20°C to +30°C, + 300 fpm

+ 250 fpm, at any height, -20°C to +50°C, + 300 fpm

+ 200 fpm, on the ground, -20°C to +50°C, + 300 fpm

+/- 200 feet per minute (fpm) when the aircraft is on the ground, within a temperature range of -20°C to +50°C.
+/- 300 feet per minute (fpm) outside this temperature range, ensuring the VSI’s accuracy is maintained within operational limits under varying temperature conditions.

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