Altimetry Flashcards
In what atmosphere is an altimeter calibrated to read?
ISA atmosphere
What is the definition of the ISA?
Average conditions of atmosphere at 40N latitude, from the sea level to 105 000 feet.
State 6 numerical specifications for the ISA up to 65000’?
MSL Temp = 15 Celsius MSLP = 1013,25hpa or 29,92 in of Hg Lapse rate = 1,98 Celsius/1000feet Tropopause Temp = -56,5 Celsius Tropopause height = 36 089,24 feet Stratospheric lapse rate = 0 Celsius/1000feet
What us the Temp in the ISA at 40T feet
-56,5 Celcius
What is the magnitude of error for pressure deviations from ISA standard?
30’ per hpa OR 1000’ per inch of Hg
True or False?
An altimeter indicates altitude by sensing temperature changes
False
True or False?
When flying at constant indicated altitude, true altitude is constant
False
True or False?
When flying along a constant pressure surface, the indicated altitude is always constant (no change to altimeter setting)
True
True or False?
When flying along a constant pressure surface the true altitude is always constant
False
True or False?
When flying at the same indicated altitude towards lower MSL pressure, you will gain true altitude.
False
True or False?
When flying at the same indicated altitude with the same MSL pressure at the surface, but temperature below you increasing, you will gain true altitude.
True
Without changing altimeter setting, by how much would your true altitude change if you were to fly from a 960hpa low to a 1040hpa high?
PC = (1040-960) * 30’/hpa = +2400 feet
An aircraft flying at FL300 from a warm airmass to a cold air mass should anticipate its true altitude to…
decrease
You are flying east and are experiencing starboard drift. Where is the low pressure?
East
2 aircraft are separated vertically by 2000’, both flying northward at constant indicated altitude. As they fly toward colder Temp, the actual vertical distance between the aircraft will….
remain constant
An aircraft flying from an area of high to low pressure and trying to maintain the same indicated altitude without adjusting the altimeter will experience….
decreasing true altitude
Increasing the Temperature below and through a layer will…
- Increase the separation between pressure level
- Raise the pressure levels
At altitude you observe a tail wind with no drift. Your true altitude is….
Staying the same
You are off from 0 MSL and clim to 10T indicated with the correct altimeter setting. At 10T the temperature is +6. What is the true altitude of the A/C?
Temp ISA at 10T=15-(2*10)= -5 \+6 - (-5) = 11 10 000 - 0 = 10 000 4 * 11 * 10 = 440' True altitude = 10000 + 440 = 10440' ASL
The altimeter setting at Edmonton is 29,92’’ and at Winnipeg it’s 30,62’’. If you flew from Edmonton to Winnipeg without updating your altimeter, the true altitude would be…
1000’ per inch of Hg
30,62 - 29,12 = 1.5 * 1000 = +1500 feet
At Calgary the elevation is 3000’ and the surface temp is -35. At indicated 17000, the temp is -30. What is your true altitude?
Temp @ 17000 = 15 - (2*17) = -19 -30 - (-19) = -11 17000 - 3000 = 14000 4 * -11 * 14 = -616 * 1.5 = -924 17000 - 924 = 16 076'
You are flying at indicated 10T over Calgary. You have 29.92’’ on your altimeter and report an OAT of -20. Calgary’s elevation is 3000’. Calgarys’s altimeter setting is 29,42’’ and surface temp is -30. What is the true altitude of the aircraft?
**Pressure 1st, Temp 2nd** 29,42-29.92 = -0.5 * 1000 = -500 (donc 9500') 15 - (2*9.5) = -4 -20 - (-4) = -16 9500 - 3000 = 6500 4 * -16 * 6.5 = -416 * 1,5 = -624' 9500' - 624' = 8876'
