Stochastic properties of total air traffic control voice communication time

Abstract

Past studies of air traffic controller communication workload have considered stochastic properties of individual communication transmission or sets of transmissions. This paper asserts that most of the stochastic variation in total communication workload is due to fluctuations in the number of required communication transmissions rather than fluctuations in the transmission lengths themselves. Both the length of transmission and the number of transmissions are assumed to be random variables. Thus, total communication workload is formulated as the sum of a random number of random variables. Expressions are derived for the mean and variance of total communication workload. An example is solved using data from related air traffic control research. Finally, suggestions are presented for incorporating statistical fluctuations in controller workload into workload capacity concepts.