A poor question as well, sorry. I meant changing my orbit so when i re-enter i'll be heading a certain way (down the runway hopefully)
You could eyeball it using MapMFD, or get a bit more precise with BaseSync (in "closest approach", heading should be 90 degrees away from the runway heading) but this is really a poor way to go about it. I'm not a pilot IRL, nor even an experienced flight simmer (other than Orbiter) but I've practiced this a LOT. It probably isn't the "textbook correct" methods, but it works.
I haven't found HSI to be useful; as noted above, by the time you're close enough for it to give you a clue you are too close to use it! You'll be within visual range of the runway by then anyway.
First, for any who don't already know, you can find a runway's heading by adding a zero to the ends of it's designation. For instance, a runway with the designation 15/33 would have approach headings of 150 or 330 degrees, depending on which way you will be landing.
Second, you'll need to decide if you'll be using a HAC manouver, which I will call an alignment turn about 270 degrees, or coming "straight in". Generally, I'll use a HAC if my heading is more than 50 degrees from the runway heading.
An example of a HAC approach would be returning to Cape Canaveral from the ISS, when approaching from the south-west. In this case, I'll use Aerobrake to set my "endpoint" about 20k south of the Cape. I'll drop out of high AoA reentry into normal flight at about 800 m/s at about 20k altitude, and try to cross south of the runway at close to a 90 degree angle. I'll use external view, or aim the internal camera (with right mouse and drag) so I can see when I cross the runway's plane. Then I'll return to normal view, bank at least 60 degrees, and begin turning away from the runway. I'll watch the G-force reading on the 2D panel and try to hold a consistent G-force of about 2.5 Gs. The exact number isn't crucial, just keep it consistent through the turn. As you decellerate, if you keep the G-force consistent you turn will "tighten" as you go along, creating an inward spiral. 270 degrees later you'll be fairly closely aligned with the runway. It helps to use the Z and X keys to widen your FOV during the HAC so the runway comes into view sooner, then narrow it back down for precision tuning on final approach.
An example of a "straight in" approach would be returning from the ISS to the Cape when approaching from the north-west. Make sure that Cape Canaveral is targeted in MapMFD. Use Aerobrake and set your "endpoint" about 45k north by northeast of the Cape. Keep an eye on the "heading to base" on MapMFD, or the carat on the surface HUD's compass. Transition to normal flight like you did for the HAC approach, but turn toward the runway. Time the turn so that you are heading 150 degrees at the same time the carat is at 150 degrees, and adjust a bit right or left when the runway becomes visible. Once again, change your FOV as needed.
For final approach, try to fly fairly level until the end of the runway is about 15 degrees down (use the pitch ladder) then drop the nose to put the velocity ball a bit short of the runway, and use airbrakes as needed to reduce speed. NOTE: Some vessels such as the shuttle or DGIV need a steeper approach angle to avoid losing to much velocity and stalling short of the runway. As you get close to the runway, move the velocity ball gradually up to the end of the runway to reduce VS.
I suggest practicing getting the alignment correct and not worrying about the landing at first. Once you can get lined up on a regular basis, start experimenting to see when you should use airbrakes, and how much, so that you cross the end of the runway at a good landing speed (this varies with vessel and load). Managing the velocity is probably trickier than getting lined up, and will take a bit of practice with each vessel.
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