Altimetry, temperature and thermodynamics

Question 1

True altitude corrects -

Answer 1

Indicated altitude for temperature error

Question 2

two altitude correction formulas:

Answer 2

4 x (height above surface / 1000) x ISA DEV or 4% change for each 10 degrees ISA DEV

Question 3

041200Z 33008KT 280V040 9999 FEW045 30/13 Q1025 NOSIG

Assume that the code applies to an aerodrome at position 25S 30E

what is the approximate density altitude at 7000feet?

(ISA temp lapse rate, a temp correction of 120 feet/degree C and pressure lapse rate of 27 feet/ hPa)

A
9500 feet

B
10000 feet

C
7300 feet

D
9200 feet

E
4400 feet

Answer 3

Height = the vertical distance above a specified datum, usually ground level
Elevation = the vertical distance above mean sea level (MSL) of a point on the earth's surface
Altitude = the vertical distance above MSL

These charts have a note on them that states: “BOXES REFER TO SPOT WINDS DEGREES TRUE AND KNOTS AT INTERSECTIONS OF THE LAT/LONG LINES COVERED BY THE BOX, TEMPERATURES DEGREES C, HEIGHTS ABOVE MSL (THOUSANDS OF FEET)”.

Step 1: Apply a pressure correction to get Pressure Altitude:
QNH = 1025
1025 - 1013 = 12 x 27 = 324ft
7000 - 324 = 6676 ft

Step 2. Apply the temperature correction:

ISA at 6676ft = 1.648°C

Our temperature = 23°C

23 - 1.648 = 21 degrees ISA deviation

21 x 120 = 2520 ft

Step 3: Calculate the density altitude:

Pressure Altitude + Temperature Correction = Density Altitude

6676 + 2520 = 9196 ft

Closest answer is 9200ft

Remember: Density altitude is PRESSURE ALTITUDE corrected for non standard temperature

Question 4

QFF is -

Answer 4

QNH corrected for non standard temperature

Question 5

Pressure Levels:

Answer 5

FL050= 850 hPa
FL10= 700 hPa
FL180= 500 hPa
FL300= 300 hPa