This has motivated the development of numerical
approaches to the problem of computing airport
delays analytically. In another landmark paper,
Koopman (1972) argued—and showed through examples
drawn from New York’s Kennedy and LaGuardia
Airports, at the time among the world’s busiest—that
the queueing behavior of an airport with k “runway
equivalents” (i.e., k nearly independent servers) can
be bounded by the characteristics of the M(t)/M(t)/k
and the M(t)/D(t)/k queueing models, each providing
“worst-case” and “best-case” estimates, respectively.