They were very close. See [1]. They were over the centerline of taxiway C, and 85 feet AGL crossing taxiway W. Minimum altitude was 2.5 secs later. There were three planes ahead, an A-340, a B-787 (also 55 feet high at the tail), and some UAL jet of about the same size.
A few feet lower and there would have been a collision.
