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 AIRCRAFTMETRICS

1. It doesn’t break very often,2. When it does break, we can fix it quickly3. 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.

POSTFLIGHT

FLYSORTIE

PREFLIGHTLOAD, ETC.

MISSIONSCHEDULE

AVAILABLEAIRCRAFT

WORKMAINTENANCE

TASKS

PEOPLE SPARESSE &

FACIL.

WORKSHOP

TASKS

CHECK IFFAILURES

YesNo

POSTFLIGHT

FLYSORTIE

PREFLIGHTLOAD, ETC.

MISSIONSCHEDULE

AVAILABLEAIRCRAFT

WORKMAINTENANCE

TASKS

PEOPLE SPARESSE &

FACIL.

WORKSHOP

TASKS

CHECK IFFAILURES

YesNo

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.

1.

2.

3.

4.

1.

2.

3.

4.

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.

READINESS/AVAILABILITYMETRICS

• Inherent Availability (Ai)

• Operational Availability (Ao)

• Operational Readiness (O.R.)

• Mission Capable (MC)

Availability

Readiness

UPTIME DOWNTIME

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Down time

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AVAILABILITY

INHERENT AVAILABILITY (Ai)

Inherent Availability, Ai, addresses only those features that can be designed into a system. Thus, Ai is generally defined as

 

Ai = ________Operating time__________Operating time + Active repair time

Ai = _________MTBF_________ MTBF + MTTR

 

OPERATIONAL AVAILABILITY (AO)

However, (Ai) 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, Ao, in the following equation:

  

Ao = _________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/Ao - 1]

MC = Mission Capable RateUTE = Utilization Rate of the aircraft (FH/possessed hours) = [SGR * ASD] / 24Ao = Operational Availability = MTBF / [ MTBF + MTTR + MLDT + TAT]

0 UTE Ao MC 1.0

EXAMPLE 1 (notional)

MC = 1 - UTE [1/Ao - 1]

Say the Aircraft X and Aircraft Y have an Ao = .7The 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 Ao, but higher tempo of Aircraft X means a lower MC rate.

EXAMPLE 2 (notional)

MC = 1 - UTE [1/Ao - 1]

Say the Aircraft X has an Ao = 0.8and Aircraft Y has an Ao = 0.75Aircraft 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 Ao, 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 Ao

– MC is a function of too many variables

• To compare Ao 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

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

Ai0.5 0.6 0.7 0.8 0.9 1.0

MCMTCF=3.0

=2.0=1.0=0.5

0.6 0.7 0.8 0.9 1.023456789102345678

1.0

0.9

0.8

0.7

0.6

0.5

1.0

0.9

0.8

0.7

0.6

SGR - 12 hour day SGR - 16 hour day

AoAo

=1.0=0.5

ASD=1.0ASD=2.0 ASD=2.5

ASD=1.0ASD=2.0 ASD=2.5

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

MFHBCF

15

20

25

30

35

40

45

6.7

8.9

11

13.3

15.5

17.8

20

MLDT=2.0

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

15

20

25

30

35

40

45

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

15

20

25

30

35

40

45

0.5 0.6 0.7 0.8 0.9 1.0

MCMTCF=3.0

=2.0=1.0=0.5

MFHBCF

6.7

8.9

11

13.3

15.5

17.8

20

Ai

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

0.6 0.7 0.8 0.9 1.0

1.0

0.9

0.8

0.7

0.6

0.5

Ao

=1.0=0.5

15

20

25

30

35

40

45

0.5 0.6 0.7 0.8 0.9 1.0

MCMTCF=3.0

=2.0=1.0=0.5

MFHBCF

6.7

8.9

11

13.3

15.5

17.8

20

Ai

MLDT=2.0

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

0.6 0.7 0.8 0.9 1.023456789102345678

1.0

0.9

0.8

0.7

0.6

0.5

1.0

0.9

0.8

0.7

0.6

SGR - 12 hour day SGR - 16 hour day

AoAo

MLDT=2.0=1.0=0.5

ASD=1.0ASD=2.0 ASD=2.5

ASD=1.0ASD=2.0 ASD=2.5

15

20

25

30

35

40

45

0.5 0.6 0.7 0.8 0.9 1.0

MCMTCF=3.0

=2.0=1.0=0.5

MFHBCF

6.7

8.9

11

13.3

15.5

17.8

20

Ai

1.0 0.95 0.9 0.85 0.8 0.75

ASD=1.0ASD=1.5ASD=2.0

ASD=2.5

Mission Reliability

MFHBOMF

0.6 0.7 0.8 0.9 1.023456789102345678

1.0

0.9

0.8

0.7

0.6

0.5

1.0

0.9

0.8

0.7

0.6

SGR - 12 hour day SGR - 16 hour day

AoAo

=1.0=0.5

ASD=1.0ASD=2.0 ASD=2.5

ASD=1.0ASD=2.0 ASD=2.5

SUPPORTABILITY(Assuming TAT = 0.5 hrs)

15

20

25

30

35

40

45

0.5 0.6 0.7 0.8 0.9 1.0

MCMTCF=3.0

=2.0=1.0=0.5

MFHBCF

6.7

8.9

11

13.3

15.5

17.8

20

Ai

MLDT=2.0

LINKAGE OF MEASURES

Combat Operations Normal Operations

Operational MetricLogistics FactorEngineering Metric

Sortie Gen.Rate

LogisticsFootprint

TATCombat

Mission CapableRate

MFHBCFMCMTCF

DMMSPA

DMMH/FH MFHBR

O&S Cost

DMMSPA

DMMH/FH MFHBR

MFHBMEMTTR MFHBME

MTTR

PFDPHM

PFIPHM

MFHBFAPHM

PFDPHM

PFIPHM

MFHBFAPHM

MissionReliability

MissionReliability

MFHBOMFMFHBOMF

MFHBCFMCMTCF

SUMMARY OF METRICS

• SGR, MR, LF– Opstempo, mission effectiveness, easily supported

– Wartime metrics

• Ai, Ao, O.R., MC– Readiness vs. Availability

– Peacetime metrics

– Strengths/weakness