![]() ![]() Radio or radar altimeters measure absolute altitude, usually up to 2,500 feet AGL. ![]() The vertical distance of the aircraft above ground level (AGL), which is true altitude minus terrain elevation. True altitude equals the indicated altitude when conditions are standard, which is rarely the case. The vertical distance of the aircraft above mean sea level (MSL), which is the indicated altitude corrected for non-standard temperature and pressure.Īirport, terrain, and obstacle elevations on aeronautical charts are true altitudes. Indicated altitude is mainly used for aircraft separation and standard operating procedures. Density-pressure altitude corrected for nonstandard temperature.The reading on the altimeter when the altimeter setting is set to the local barometric pressure.Īltimeters display altitude in feet in the United States and most of the world, but a few countries such as Russia use meters.Pressure-indicated altitude with altimeter set to 29.92.Indicated-shown on the aircraft’s altimeter when set to current altimeter setting.Note: Temperatures above standard and altimeter settings below 29.92 will increase density altitude and decrease aircraft performance. Density altitude in feet = pressure altitude in feet + (120 x (OAT – ISA temperature)).Or, in a pinch, here’s a quick density altitude formula: You can find these in the FAA’s Density Altitude pamphlet. The Koch Chart connects an airport’s pressure altitude with an airport’s temperature to calculate decreased rated of climb and increased takeoff distance percentages. Two other handy graphs are the FAA’s Rule-of-Thumb chart and the Koch Chart. In addition, the FAA’s Pilot’s Handbook of Aeronautical Knowledge (PHAK) provides a Density Altitude graph to help you convert OAT and pressure altitude into density altitude. There are various methods you can use.įor example, you should consult your aircraft’s pilot’s operating handbook (POH), but there are other tools that can help like an e6B, an electronic flight bag, or an online density altitude calculator such as NOAA’s. ![]() High density altitude conditions require calculating what your aircraft’s actual performance will be during takeoff, cruise, and landing. Note: Altimeter settings below 29.92 will increase density altitude and decrease aircraft performance. Then calculate the density altitude for the various temperatures listed on the poster for a quick and easy reminder of how a few degrees can affect your aircraft’s performance. For both printed and downloaded posters, at the top of the poster, fill out your airport’s name, elevation, and standard temperature. #DENSITY ALTITUDE PDF#In the meantime, please download a smaller 11x17" PDF version that has fillable text fields so it can also be easily modified for use at your airport. Once you submit the request form, we’ll mail the posters to you. Please request up to 10 printed 18x24" posters, large enough to prominently display at your airport, flying club, flight school, FBO, and backcountry strip. It’s a great reminder for you and other pilots of local conditions impacting density altitude and aircraft performance. The AOPA Air Safety Institute has developed a Density Altitude Poster to modify and use as a quick tool for knowing the density altitude values at your airport on a standard day. In a sense, it’s the altitude at which the airplane “feels” its flying. But when that airport’s outside air temperature (OAT) is 30 degrees Celsius (85 degrees Fahrenheit), the density altitude will be 8,000 feet and your airplane will perform as if it is taking off and landing at an elevation of 8,000 feet. For example, at an elevation of 5,000 feet above sea level, an airport’s standard temperature would be 5 degrees Celsius (41 degrees Fahrenheit). The standard temperature at sea level is 15 degrees Celsius (59 degrees Fahrenheit) and the temperature gradient from sea level is minus 2 degrees Celsius (3.6 degrees Fahrenheit) per 1,000 feet. Airport location, elevation, and temperatures that differ from international standard atmosphere (ISA) temperatures determine how density altitude will influence your aircraft’s performance at that airport. ![]()
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