Presentation on theme: "WEAPON SYSTEM PERFORMANCE INDICATORS 24 Feb 2004 Roy E. Rice, Ph.D., P.E. Chief Scientist, Teledyne Brown Engineering."— Presentation transcript:
WEAPON SYSTEM PERFORMANCE INDICATORS 24 Feb 2004 Roy E. Rice, Ph.D., P.E. Chief Scientist, Teledyne Brown Engineering
AGENDA General Concerns –Context for Metrics –Definitions/equations –Strengths and Weaknesses –Candidate Metrics Fighter Aircraft –Metrics to cover full spectrum Readiness/Availability Linkages of the Metrics Summary
CONTEXT FOR METRICS Metrics derived from Strategy-to-Task decomposition Wartime vs. Peacetime Metrics Metrics to Influence Design Parsimony of Metrics Mostly Aircraft related Metrics
FIGHTER AIRCRAFT METRICS 1.It doesn’t break very often, 2.When it does break, we can fix it quickly 3.We don’t have to take a lot of stuff with us to accomplish this Mission Reliability (MR) – measures effectiveness of mission Sortie Generation Rate (SGR) – measures optempo Logistics Footprint (LF) – measures how much “stuff” is required to support wartime operations
DEFINITIONS Sortie Generation Rate (SGR) - The number of sorties flown per aircraft per day for the entire number of Primary Authorized Aircraft (PAA). It is defined as Total Sorties per day divided by PAA. Function of: sortie schedule (series of ATOs), operational flying window, deck cycle (shipboard), aircraft turn around times, mission reconfigurations, taxi and towing task times, supply support, reliability, maintainability, adequacy of support equipment inventories, adequacy of maintenance training, quality control, and maintenance management. It’s scenario dependent. SGR is a wartime measure of the supportability and the operational usage of a unit (squadron) of aircraft.
DEFINITIONS Mission Reliability (MR) - Probability of completing entire sortie without failure of any Mission Essential Function - assumes aircraft was MC at start of sortie. Function of: sortie duration and mean-flying-hours-between-operational-mission- failure (MFHBOMF). Not a function of supportability of the aircraft. MR is a “snapshot” measure…only of Reliability of a single mission.
DEFINITIONS Logistics Footprint (LF) –e.g., “spares, support equipment, advance-party personnel, etc. to support a 30-day self sustained deployment at specified/required sortie rates… exclusive of POL and ordnance.” Must specify groundrules about what is included and what is not included in the LF; e.g., Tanks-racks, pylons (TRAP), bomb-builders, fuel trucks, etc. LF is a measure of how deployable and supportable a weapon system is.
Why no fewer than SGR, Log Footprint, MR? –SGR and Footprint only - inadequate MR will mean ineffective sorties –Log Footprint and MR only - repair times might be so high that we can’t generate adequate numbers of sorties –SGR and MR only - generate adequate numbers of effective sorties, but takes too long to get to the fight. O&S cost not captured Why no more than SGR, Log Footprint, MR? –SGR and Footprint constrain manpower down to reasonable numbers –SGR, Footprint, and MR constrain wartime spares usage –SGR and MR constrain peacetime spares pipelines down –SGR and MR constrain the values of MCMTOMF –Captures O&S cost drivers PARSIMONY
READINESS/AVAILABILITY METRICS Inherent Availability (A i ) Operational Availability (A o ) Operational Readiness (O.R.) Mission Capable (MC) Availability Readiness UPTIMEDOWNTIME
Available Unavailable System status Time Horizon Idle time Turnaround time Operating time Admin time Admin and logistics delay time Active repair time Time Down time Turnaround time AVAILABILITY
INHERENT AVAILABILITY (A i ) Inherent Availability, A i, addresses only those features that can be designed into a system. Thus, A i is generally defined as A i = ________Operating time__________ Operating time + Active repair time A i = _________MTBF_________ MTBF + MTTR
OPERATIONAL AVAILABILITY (A O ) However, (A i ) does not account for “operational realism.” Often, there are maintenance delays due to waiting on resources. These resources may be spare parts, support equipment, technical data, test equipment, or personnel. These “delay” times, as shown below the time line in the above figure, are thus included into Operational Availability, A o, in the following equation: A o = _________MTBF_________ MTBF + MTTR + MLDT + TAT where MLDT is “mean logistics delay time” which is all that other time below the line that consumes time and must be accomplished to return the aircraft to the “available” state. TAT is aircraft turnaround time.
OPERATIONAL READINESS (O.R.) Finally, once the aircraft is repaired, it may not be immediately placed in an operating state (may not fly immediately…it may sit in a hangar until sunrise). It is in an “available” state but just not being used. So, to account for this, the term Operational Readiness (O.R.) is used to express the “readiness” state of the aircraft. O.R. is defined as O.R. = ________MTBF + Mean Idle Time_______ MTBF + MTTR + MLDT +TAT + Mean Idle Time O.R. is now clearly seen as the portion of the total time line that the aircraft is above the line or in an “available” state.
DEFINITIONS Mission Capable Rate (MC Rate ) - Percentage of time within a particular reporting period in which the aircraft can accomplish at least one of its assigned missions as designated in the Mission /Minimum Essential Subsystems Listings ( MMESL). ( Readiness ) MC Rate = FMC + PMCS + PMCM Function of: flying hours over that reporting period, supply support, reliability, maintainability, adequacy of support equipment inventories, adequacy of maintenance training, quality control, and maintenance management. MC Rate is a dynamic measure of the readiness of unit or fleet of aircraft. Usually a Peacetime measure. Doesn’t drive design of the aircraft.
BASIC EQUATION MC = 1 - UTE [1/A o - 1] MC = Mission Capable Rate UTE = Utilization Rate of the aircraft (FH/possessed hours) = [SGR * ASD] / 24 A o = Operational Availability = MTBF / [ MTBF + MTTR + MLDT + TAT] 0 UTE A o MC 1.0
EXAMPLE 1 (notional) MC = 1 - UTE [1/A o - 1] Say the Aircraft X and Aircraft Y have an A o =.7 The Aircraft X has an SGR = 3.0 and ASD = 2, Aircraft Y has SGR = 2.0 and ASD = 1.5 Then MC(a/c X) = 0.893, MC(a/c Y) = 0.946 *** Both aircraft have same A o, but higher tempo of Aircraft X means a lower MC rate.
EXAMPLE 2 (notional) MC = 1 - UTE [1/A o - 1] Say the Aircraft X has an A o = 0.8 and Aircraft Y has an A o = 0.75 Aircraft X has an SGR = 3.0 and ASD = 2, Aircraft Y has SGR = 2.0 and ASD = 1.5 Then MC(a/c X) = 0.938, MC(a/c Y) = 0.958 *** Aircraft X has greater A o, but higher tempo of Aircraft X means a lower MC rate.
DISCUSSIONS ON COMPARISONS To compare MC rates on different aircraft is risky –Driven by tempo (UTE) –Holding tempo (UTE) constant for both aircraft is not realistic…PLUS, this just reduces to comparing A o –MC is a function of too many variables To compare A o is also dangerous –The many users (across services) rejected using Ao as a measure of readiness/availability because it doesn’t reflect tempo Better measure is a combination of measures (KPPs) We should encourage a comparison based on basic measures - Reliability, maintainability, MMH/FH