# what is the actual force causes this issue according to IAS that shows normal descend speed?

When we have tail wind during approach , with respect of Aerodynamic forces that effect on airplane , the whole part of fuselage move forward due to tailwind, also we have about 70kts IAS (in general aviation) . In this situation we unable to make normal descend as the same as no wind condition . Now my question is : what is the actual force causes this issue according to IAS that shows normal descend speed?

• It's not a force. It's a velocity that causes the differences. Assuming you are defining "normal descent" as given glide path relative to the ground, rather than a given descent rate. Jul 21 '20 at 17:28
• If you are just going for a given descent rate and you don't care about the glide path w/ respect to the ground, then the basic premise of the question is flawed; there is no issue at all; the required combinations of angle-of-attack (or pitch attitude) and power setting are identical in the cases with and without the tailwind. The question could use more clarification as to whether your goal is a given vertical speed, or a given glide path with respect to the ground; and if the former, then the question needs improvement because it is based on a flawed premise. Jul 21 '20 at 21:54
• Related, but probably contains too much detail until the more basic priniciples are thoroughly understood -- aviation.stackexchange.com/a/56259/3468 Jul 21 '20 at 22:11
• Anyway, will wait till the question is a bit clearer before attempting to convert some of these comments into an actual answer. Jul 21 '20 at 22:29
• Are you asking why you need less power when trying to descend on a given glide slope (with respect to ground) w/ a tailwind, than in no wind, using the same airspeed in both cases? And in more detail what is the force that causes this difference, or if it's not a force, then what is causing the difference? Critical to specify what you are holding constant (I'm guessing glide path respect to ground, and airspeed) and what you are allowing to vary (I'm guessing power, and vertical speed, and naturally groundspeed too.) But it's not clear from the question as it stands at present. Jul 21 '20 at 22:33