Definition
Order backlog that has passed the customer-requested date but has not yet shipped (measured by amount or line count), with the same definition as OTD, always against the customer-requested date, not the supplier-committed date.
In detail
Past Due Backlog (PDBL) refers to the backlog of orders that have passed the customer-requested date but have still not shipped (definition consistent with OTD, based on the customer-requested date rather than the promised date), and is a key metric for measuring supply chain delivery performance. It reflects anomalies in planning, production, materials, and other areas, and directly affects customer satisfaction and corporate reputation. Unlike order backlog (normal in-transit), PDBL specifically refers to the overdue portion. It typically outputs a past due order list (including order number, days overdue, and reason) to drive root cause analysis and Kaizen actions.
Example in practice
An electronics factory tracked PDBL monthly and found that overdue orders for a certain product model were increasing. Through analysis, they found it was caused by delays in a key material supply. They formed a cross-functional team, collaborated with the supplier for improvement, and adjusted safety stock. One month later, PDBL significantly decreased and customer complaints reduced.