Dani Ramos: How do we win?
Grace: We win... by keeping you alive.
Dani: What did you tell them?
T-800: I told them you coming here makes this place unsafe for them. Also, the day I warned them might come, has come. My past has caught up with me. And...I won't be back.
Sarah Connor: I'll be back.
Grace: Who are you?
Sarah Connor: My name is Sarah Connor. I've never seen one like you before. Almost human.
Grace: I am human.
Grace: Why do you care what happens to her?
Sarah Connor: Because I was her.
Dani Ramos: Two days ago, I had this nice, simple life. And now it's a nightmare.
Sarah Connor: My name is Sarah Connor. August 29th, 1997 was supposed to be Judgment Day. But I changed the future. Saved 3,000,000,000 lives. Enough of a résumé for you?
Grace: No. You may have changed the future, but you didn't change our fate.
Answer: The simplest answer is, this is a movie, and movies often exaggerate, change, or fabricate details that logically could never occur in real-life. This is a perfect example of a deliberately faked action sequence that is contrived solely to entertain the audience by employing a 'suspension of disbelief.' It's more exciting and suspenseful to be able to see the plane crash, even though, as you point out, it realistically would be miles away by that time.
raywest ★