Availability of Weapon Systems with Air-attack Missions

Abstract

During air-attack operations, i.e., air-to-air and land-air operations in battles, maintaining a high level of availability of weapon systems (aircraft and weapons) becomes important from the point of view of winning the battle. Availability may depend on severity of combat operations, attrition factors (battle damage failures and reliability related failures), and logistic delays in weapons deployment and in the repair process. In this paper, a simulation model is developed for availability of weapon systems considering air-to-air and land-air combat operations, multiple failures causing aircraft failure and logistic delays in weapons deployment, and in the repair process. The availability of aircraft and the availability of weapons are separately derived from simulation and the product of them is denoted as combined availability for analysis. The results are analyzed in terms of fluctuations in availability on specified days of battle such as 1, 7, 14, and 21 days from the graphical output. The simulation procedure employs discrete event simulation technique using Monte Carlo methods. The time to failure distribution and the time to repair distribution for the major subsystems of the aircraft and helicopters is considered to be Weibull and exponential respectively. The logistic delay time distribution for weapons replenishment and for logistic factors, spares, crew, and equipment, is considered to be lognormal. Assuming a certain range of values for air-attack missions and for the number of sorties to be generated and a set of reliability and maintainability parameters for the considered major subsystems of the aircraft, the simulation for availability is analyzed. The number of aircraft (both fixed wing and rotary wing) for different missions is varied. The possible reduction in availability due to changes in logistic factors, considering two extreme cases noted as optimistic and pessimistic is specifically examined through simulation runs. The results obtained indicate the pronounced decrease in availability of weapon systems and their fluctuations due to multiple failures and logistic delays in weapons replenishment and in the repair process. The results are, however, highly sensitive to a combination of reliability, maintainability, and logistic delay parameters.