AIR TEMPERATURE MEASUREMENT - Dgca question bank for pilots

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#1. Converted into degrees Celsius – 40°F is:

-56.5°C

-40°C

-20°C

-108°C

#2. In an aircraft thermometer with an electrical resistance sensor to measure the air temperature, the resistance wire element is probably:

plutonium

platinum

potassium

beryllium copper

#3. Flying at high speed at high altitude, the difference between ram air temperature and static air temperature is:

likely to be less than when flying low and slow.

due to adiabatic cooling.

due to adiabatic warming.

proportional to the square of the absolute temperature.

Flying at high speed at high altitude, the difference between ram air temperature (RAT) and static air temperature (SAT) is typically:

RAT is generally higher than SAT due to the compressibility effects and dynamic heating that occurs when an aircraft is moving through the air at high speeds.

The difference can be significant, particularly at high altitudes and high speeds, where the air pressure and temperature drop, but the kinetic energy from the aircraft’s speed increases the air temperature in front of the aircraft.

#4. Aircraft air temperature thermometers are shielded to protect them from:

solar radiation.

accidental physical damage on the ground or hailstones in flight.

airframe icing.

kinetic heating.

Aircraft air temperature thermometers are shielded to protect them from:

Solar Radiation: Shielding helps prevent direct sunlight from artificially warming the thermometer and affecting its readings.
Engine Heat: Proximity to engine exhaust can cause higher temperatures that would lead to inaccurate measurements.
Airframe Heat: Heat generated by the aircraft’s structure during flight can also affect the accuracy of temperature readings.
Precipitation and Debris: Shields can protect sensors from moisture, ice, and other particulates that could impede their function.
Wind Chill Effects: Shielding helps to provide a more accurate representation of the actual air temperature rather than the temperature influenced by wind chill.

#5. At a true airspeed of 500 knots, a ram rise of air temperature can be expected of:

50°C

25°C

5°C

16°C

Summary

This formula provides a quick and practical way to estimate ram air temperature rise while flying.
It’s noted that while this approximation is useful for in-flight calculations, it’s not as precise as other methods (like those provided in the CRP5).
This approximation can help pilots make quick decisions when a nav computer or lookup table isn’t readily available.

#6. An air temperature probe may be aspirated in order to:

prevent icing.

measure air temperature on the ground.

compensate for thermal soaking at the ramp position.

reduce the effect of solar radiation.

An air temperature probe may be aspirated in order to:

Improve the accuracy of temperature readings by ensuring proper airflow over the sensor.
Prevent heat buildup or stagnation around the probe, which can lead to erroneous readings.
Reduce the effects of radiation or heat from surrounding structures.
Enhance the probe’s response time by ensuring a consistent air supply for faster adjustments to temperature changes.

#7. Total Air Temperature is:

the maximum temperature attainable by the air when brought to rest, adiabatically.

the temperature indicated on the air temperature thermometer plus the ram rise.

the static air temperature minus the recovery factor.

the recovery factor plus the ram rise.

Total Air Temperature (TAT) is the temperature of the air measured by an aircraft in flight, which includes both the static air temperature (SAT) and the additional temperature rise due to the aircraft’s motion through the air (ram effect).

It is higher than the static air temperature because of the compressional heating and friction caused by the aircraft’s speed. TAT is used to calculate the true air temperature and other important performance parameters.

#8. The difference between static air temperature and total air temperature is known as:

corrected outside air temperature.

the ram rise.

the recovery factor.

hot ramp radiation.

The difference between Static Air Temperature (SAT) and Total Air Temperature (TAT) is known as ram rise or ram air temperature rise. This difference occurs due to the compressional heating of the air as the aircraft moves through it, especially at higher speeds.

#9. A direct reading aircraft thermometer usually consists of a bimetallic helix protruding into the airstream. Movement of the pointer over the temperature scale will depend upon:

difference in electrical resistance of the two metals.

increase in pressure as airspeed increases.

increase in adiabatic cooling as airspeed increases.

different coefficients of expansion of the two metals.

A direct reading aircraft thermometer, typically consisting of a bimetallic helix protruding into the airstream, operates based on the expansion and contraction of the bimetallic strip in response to temperature changes. The movement of the pointer over the temperature scale depends upon the differential expansion of the two metals in the helix as they heat or cool, causing the strip to twist, which moves the pointer to indicate the temperature.

#10. A remote reading thermometer depends upon ……. to indicate changes in temperature:

change of electrical resistance of the two metals.

change of electrical resistance with temperature.

change of electrical resistance with change in pressure.

change of electrical capacitance with change in temperature.

A remote reading thermometer depends upon electrical resistance or thermocouple voltage to indicate changes in temperature. In resistance-based thermometers, the temperature is measured by detecting changes in the resistance of a metal wire, usually platinum, as the temperature changes. In thermocouple-based systems, the temperature is determined by measuring the voltage generated by the junction of two different metals exposed to temperature variations.

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