![]() This means that the temperature is 7 ☌ warmer than the given ISA temperature for that altitude. Using our example, to calculate the deviation from ISA:Ħ ☌ (actual OAT at 8000ft) -1☌ (ISA temperature at 8000ft) = Deviation of +7☌. Higher than ISA temperatures, in particular, will negatively affect performance in various phases of flight such as take off, cruise and climb, so be sure to check your aircraft’s performance graphs, especially if the temperature is high, the altitude is high, and you are carrying a heavy load. ![]() In order to determine how the aircraft will perform, we need to work out what the deviation is. If the actual OAT at 8000ft is 6☌, then we can see that there is a difference with the ISA temperature which is -1☌. So, as an example, if the chosen altitude is 8000ft then we calculate it like this:Ĩ x -2 = -16 now add +15 (which is the ISA temperature at MSL) = -1☌ For practical, and exam purposes, we can safely use a 2☌ decrease per 1000ft that we climb. Remember that according to ISA, the temperature will decrease by 1.98☌ per 1000ft from mean sea level (MSL). ![]() ![]() The first step is to check what the standard (ISA) temperature is for your chosen altitude. However, if the actual outside air temperature (OAT) differs from the ISA for the particular altitude or flight level that you are at, then this will affect your aircraft’s performance. Let’s start with a brain jiggle – ISA (International Standard Atmosphere) was created in order to standardise aircraft instruments, and thus provides a common reference for both pressure, and temperature. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |