Four digit flight numbers starting with 9 are often "extra sections" which are not ordinarily scheduled. https://www.travelersunited.org/today/whats-an-extra-s

Four digit flight numbers starting with 9 are often "extra sections" which are not ordinarily scheduled. https://www.travelersunited.org/today/whats-an-extra-section-another-reason-to-use-a-travel-agent/ https://www.travelersunited.org/today/whats-an-extra-section...