private void btntracuu_Click(object sender, EventArgs e)
 {
     TraCuuChuyenBay f = new TraCuuChuyenBay();
     f.Show();
 }
 private void traCứuChuyếnBayToolStripMenuItem_Click(object sender, EventArgs e)
 {
     TraCuuChuyenBay f = new TraCuuChuyenBay();
     f.Show();
 }