Determine the density altitude by entering the chart at +25☏ proceed upward to the 3,500-foot pressure altitude line from the point of intersection move to the left edge of the chart and read a density altitude of 2,000 feet. Subtract the correction factor from the airport elevation to find pressure altitude: 3,894 – 394 = 3,500 feet MSL (pressure altitude)Ħ. Add the amount of difference to the amount shown for the 30.30″ Hg conversion factor: -348 + (-46) = -394 feetĥ. Determine amount of difference to be added to the 30.30″ Hg conversion factor: -92.0 x. Determine the difference between the two factors: -440 + 348 = -92 feetģ. Locate the settings immediately above and below the given value of 30.35″ Hg:Ģ. Since the altimeter setting that is given is not shown in FAA Figure 8, interpolation is necessary. Determine the density altitude by entering the chart at +81☏ move upward to the 5,876 pressure altitude line from the point of intersection, move to the left and read a density altitude of 8,500 feet.ģ- (Refer to Figure 8.) Determine the density altitude for these conditions:ġ. Add the correction factor to the airport elevation to find pressure altitude: 5,250 + 626 = 5,876 feet MSL (pressure altitude)Ħ. Add the amount of difference to the amount shown for the 29.30″ Hg conversion factor: 579 + 47 = 626 feetĥ. Determine the amount of difference to be added to the 29.30″ Hg conversion factor: 94 x. Determine the difference between the two conversion factors: 673 – 579 = 94 feetģ. Locate the settings immediately above and below the given value of 29.25″ Hg:Ģ. Determine the change in density altitude:Ģ- (Refer to Figure 8.) Determine the density altitude for these conditions:ġ. From the point of intersection, move left to the edge of the chart and read a density altitude of 5,500 feet.ģ. Proceed upward to the 5,000-foot pressure altitude line. From the point of intersection, move left to the edge of the chart and read a density altitude of 3,850 feet.Ģ. Proceed upward to intersect the 5,000-foot pressure altitude line. Referencing FAA Figure 8, use the following steps:ġ. (Refer to Figure 8.) Determine the density altitude for these conditions:ġ- (Refer to Figure 8.) What is the effect of a temperature increase from 25 to 50☏ on the density altitude if the pressure altitude remains at 5,000 feet? (Refer to Figure 8.) Determine the density altitude for these conditions:ģ. (Refer to Figure 8.) What is the effect of a temperature increase from 25 to 50☏ on the density altitude if the pressure altitude remains at 5,000 feet?Ģ. Try a few calculations on your own and see how you do, these are questions you will likely see on your Private Pilot FAA Knowledge Exam. The current density altitude at Big Bear is 9,019 this is more than 2,200 feet above the already high airport elevation. With the given information above we can determine the density altitude with our CX-2 flight computer, as the video below will demonstrate. Next I will need the current METAR (assuming it’s a nice summer day in August): This piece of information alone should start to raise some concerns regarding aircraft performance-this is pretty high. Using the AF/D I determined an airport elevation of 6,752 feet. For this example we will use Big Bear City Airport (元5). The first step is obtaining the airport data and current weather information. Understanding the effects of density altitude is one thing but knowing how to determine the density altitude at any given point is another, so today let’s cover how to determine your density altitude. If you take away one thing from that post remember this: Higher Density Altitude = Decreased Performance. Be particularly aware when your conditions are hot, high or heavy-all indications your density altitude is going to negatively impact your aircraft performance. Two very important altitudes were discussed Pressure Altitude and Density Altitude both of which are significant when determining aircraft performance. Monday’s post introduced us into the subject of aircraft performance, focusing on how the environment we fly in, specifically the atmosphere and altitude, can affect the overall performance of the aircraft.
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