Does the foundation laid by 'By 8:33, it had reached its assigned cruising altitude of 31,000 feet.' logically support 'By 8:33 is was on its delegated cruising altitude of about 30,000 feet.'
By 8:33, it had reached its assigned cruising altitude of 31,000 feet.###By 8:33 is was on its delegated cruising altitude of about 30,000 feet.