Originally Posted by
ahramin
When flying a visual circuit yes, turns are 90°. If the runway direction is 180°, downwind track is 360°, base is 90°, and final is 180°. It's very simple and there's no need to worry about air masses.
Give any aircraft 25kts tailwind on base, and you will see the effect of the 90° turn thinker. He will overshoot final and end up high on glideslope. Happens on c172, but also on simple LOC intercepts on Boeing 737 unfortunately... because your track line when you start the turn does not give you any clue of the track line leaving the turn. Track lines don’t anticipate future wind, they are a depiction of your actual situation. Even though track changes are 90°, your aircraft will have to turn more, and we fly the required HDG changes. If your APFD used 25° bank standard on vectors... you will overshoot. (777 was crazy in this respect as far as I remember)
Again, we can provide track changes to ATC, no problem. But to maneuver and to know how much, we need HDG on our display. This is how our visual brains are trained when we learn to fly, and this is transfered in IFR through headings.