Based on the premise 'By 8:33, it had reached its assigned cruising altitude of 31,000 feet.', does it logically lead to the hypothesis 'By 8:33, it hadn't climbed to above 20,000 feet.'
By 8:33, it had reached its assigned cruising altitude of 31,000 feet.###By 8:33, it hadn't climbed to above 20,000 feet.