Does 'Just before 8:14, it had climbed to 26,000 feet, not quite its initial assigned cruising altitude of 29,000 feet.' offer a contrasting position to 'It climbed to 30,000 feet by 8:13.'
Just before 8:14, it had climbed to 26,000 feet, not quite its initial assigned cruising altitude of 29,000 feet.###It climbed to 30,000 feet by 8:13.