FAA figures/8080-2H/Figure 8

Figure 8: Density altitude chart

FAA-CT-8080-2H · Sport, Recreational, Private & Remote Pilot supplement · asked on the Private Pilot, Private Pilot Helicopter test

FAA Figure 8Density altitude chartFAA-CT-8080-2H · Sport, Recreational, Private & Remote Pilot supplement
How to read it: Start at the outside air temperature on the bottom, go up to the pressure-altitude diagonal, then left to read density altitude. The right-hand table converts altimeter setting to pressure altitude.

6 FAA questions that refer to this figure

  1. Question 1 · Private Pilot

    (Refer to FAA-CT-8080-2H, Figure 8.) What is the effect of a temperature increase from 35 to 50°F on the density altitude if the pressure altitude remains at 3,000 feet MSL?

    • A.1,000-foot increase.
    • B.1,100-foot decrease.
    • C.1,300-foot increase.
    Show answer and explanation

    Correct: A. 1,000-foot increase.

    On Figure 8, follow the 3,000-foot pressure altitude line. At 35 degrees F it is at about 1,900 feet density altitude, and at 50 degrees F about 2,850-2,900 feet. The difference is roughly +960 feet, about a 1,000-foot increase, which matches the usual rule that density altitude rises about 65 feet per degree F. Warmer air always raises density altitude, so a decrease is impossible, and 1,300 feet overstates the chart's change.

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  2. Question 2 · Private Pilot Helicopter

    (Refer to FAA-CT-8080-2H, Figure 8.) What is the effect of a temperature increase from 35 to 50°F on the density altitude if the pressure altitude remains at 3,000 feet MSL?

    • A.1,000-foot increase.
    • B.1,100-foot decrease.
    • C.1,300-foot increase.
    Show answer and explanation

    Correct: A. 1,000-foot increase.

    On Figure 8, follow the 3,000-foot pressure altitude line. At 35 degrees F it is at about 1,900 feet density altitude, and at 50 degrees F about 2,850-2,900 feet. The difference is roughly +960 feet, about a 1,000-foot increase, which matches the usual rule that density altitude rises about 65 feet per degree F. Warmer air always raises density altitude, so a decrease is impossible, and 1,300 feet overstates the chart's change.

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  3. Question 3 · Private Pilot

    (Refer to figure 8.) What is the effect of a temperature decrease and a pressure altitude increase on the density altitude from 90 °F and 1,250 feet pressure altitude to 55 °F and 1,750 feet pressure altitude?

    • A.1,300-foot decrease.
    • B.1,700-foot decrease.
    • C.1,700-foot increase.
    Show answer and explanation

    Correct: B. 1,700-foot decrease.

    On the Figure 8 chart, 90 degrees F at 1,250 feet pressure altitude gives a density altitude of about 3,600 feet, while 55 degrees F at 1,750 feet gives about 1,900 feet. The density altitude therefore decreases by roughly 1,700 feet: the cooler air outweighs the 500-foot increase in pressure altitude. (Check: DA is about PA + 120 x (OAT - ISA) in degrees C: 1,250 + 120 x (32.2 - 12.5) = 3,610 and 1,750 + 120 x (12.8 - 11.5) = 1,906.)

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  4. Question 4 · Private Pilot

    (Refer to figure 8.) Determine the pressure altitude at an airport that is 1,386 feet MSL with an altimeter setting of 29.97.

    • A.1,341 feet MSL.
    • B.1,451 feet MSL.
    • C.1,562 feet MSL.
    Show answer and explanation

    Correct: A. 1,341 feet MSL.

    In the Figure 8 table the conversion factor is 0 for 29.92 and -73 for 30.0; interpolating for 29.97 gives about -46 feet. Pressure altitude = 1,386 - 46 = about 1,340 feet, matching 1,341 feet. Adding the correction instead of subtracting would give about 1,431 or more.

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  5. Question 5 · Private Pilot

    (Refer to figure 8.) Determine the pressure altitude with an indicated altitude of 1,380 feet MSL with an altimeter setting of 28.22 at standard temperature.

    • A.2,913 feet MSL.
    • B.2,991 feet MSL.
    • C.3,010 feet MSL.
    Show answer and explanation

    Correct: B. 2,991 feet MSL.

    The Figure 8 table gives +1,630 feet for 28.2 and +1,533 for 28.3, so 28.22 is about 1,630 - 19 = +1,611 feet. Pressure altitude = 1,380 + 1,611 = about 2,991 feet. (Temperature does not enter into pressure altitude.)

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  6. Question 6 · Private Pilot

    (Refer to figure 8.) Determine the pressure altitude at an airport that is 3,563 feet MSL with an altimeter setting of 29.96.

    • A.3,527 feet MSL.
    • B.3,556 feet MSL.
    • C.3,639 feet MSL.
    Show answer and explanation

    Correct: A. 3,527 feet MSL.

    For an altimeter setting of 29.96, interpolating between 0 (29.92) and -73 (30.0) in the Figure 8 table gives about -37 feet. Pressure altitude = 3,563 - 37 = about 3,527 feet. A setting above 29.92 always gives a pressure altitude lower than field elevation, which rules out the other two values.

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