I was always thinking of TAS increasing, not KIAS decreasing. And TAS was this mythical number that increased as you experienced decreased performance. This makes more sense.
Thank you for the video. I still can't go over one detail. Static port will also sense less pressure in higher higts. Since the indicated speed is diff between tube and static port, how come it decreases if the both sensors sense equally less. What am I missing?
Indicated airspeed is the difference between the pressure measured by the pitot tube and the static port. Both measure static pressure so this is canceled out. Pitot = static + ram pressure. Static is only static pressure, so the difference is only ram pressure. Which goes down as you go up, so indicated airspeed goes down when you go up for the same true airspeed.
Im still confused as to why indocated speed and true air speed are needed. Just doesn't make sense to me why anyone would need to know how fast the air molecules are moving as opposed to ground speed. To me ground speed is the only speed that is relevant. Thats the speed it takes to you arrive from point A to point B right?
Think about it like this, you need to know rate and number of the air molecules passing over the wings, because the rate at which they’re passing impacts whether you’re about to stall and airflow is about to breakdown or whether it’s about to rip your wings off - IAS. You need to know the speed of the air molecules passing in general so that you know how fast the actual aircraft is moving through the air, regardless of the number of molecules, their temperature etc in order to work out how was you will arrive somewhere - TAS.
I think it’s because all the ground speed you lose with a headwind still appears on your asi. Like 120kt ias with a 30kt headwind your ground speed is 90 kts but the extra 30kt headwind is still giving you the 120kt reading on your asi. So the wind is constantly affecting the Ram pressure which is why we calculate groundspeed. Don’t trust me on that though I’m kind of dumb lol.
