Logistics Response Time (LRT)
DAU GLOSSARY DEFINITION
- The amount of time (measured in mean days) that elapses from the date a customer establishes a requisition to the date the customer receives the material that was ordered.
- It is a supply chain metric that measures the time between the date a requisition is established and the date the requisitioned materiel is received and posted by the requisitioner. LRT measures that elapsed time in days.
- It is the time that is consumed from the point when a system support requirement is first identified until that requirement has been satisfied. This may include the time required for the provisioning and procurement of a new item, the time to ship an item from inventory to the location of need, the time required to acquire the necessary personnel or test equipment for maintenance, etc..
- DoD Performance Based Logistics (PBL) Guidebook: A Guide to Developing Performance-Based Arrangements
- Defense Logistics Agency (DLA) Manual 4000.25, Defense Logistics Management System (DLMS), Volume 6, Logistics Systems Interoperability Support Services
- Logistics Engineering and Management, 6th edition, by Benjamin S. Blanchard
As can readily be seen from the above definitions, LRT is not consistently defined, and is often confused with other frequently-used response metrics such as Customer Wait Time (CWT) and Mean Logistics Delay Time (MLDT). Some organizations define LRT to include all the time beginning at identification of a failure or malfunction and ending upon the satisfaction of any logistics requirements--including personnel, spares, or any other need identified to correct the malfunction. It also includes corrective maintenance time. Others - such as the DLA definition above - are focused solely on the supply system.
Therefore, as with other metrics (particularly those used in a PBL environment), care must be taken to appropriately define the parameters of the metric and achieve a common understanding of that definition among the various stakeholders. As noted in the Product Support Manager (PSM) Guidebook, ..."these metrics must be mathematically and qualitatively described before they are useful." Additionally, also per the PSM Guidebook, they should be:
- Linked to system level required sustainment metrics objectives
- Appropriate to scope and responsibility
- Specify unit of measure
- Specify acceptable range or threshold
- Motivate desired long-term behavior
- Understood and accepted
- Easy to collect data and verify
- Readily assessed
- Analyzed to provide timely feedback
In summary, LRT is but one of many possible expressions of downtime and as such potentially may be used as an element of an Operational Availability (Ao) calculation. To re-emphasize, if used in such a calculation, LRT must be carefully defined as to what elements of downtime it includes and how it is measured, i.e., when the clock starts and when it stops.