Editing Latency (engineering) (section)

==Workflow==
Any individual [[workflow]] within a system of workflows can be subject to some type of operational latency.  It may even be the case that an individual system may have more than one type of latency, depending on the type of participant or goal-seeking behavior.  This is best illustrated by the following two examples involving [[air travel]].

From the point of view of a passenger, latency can be described as follows.  Suppose John Doe flies from [[London]] to [[New York City|New York]].  The latency of his trip is the time it takes him to go from his house in England to the hotel he is staying at in New York.  This is independent of the throughput of the London-New York air link &ndash; whether there were 100 passengers a day making the trip or 10000, the latency of the trip would remain the same.

From the point of view of flight operations personnel, latency can be entirely different.  Consider the staff at the London and New York airports.  Only a limited number of planes are able to make the transatlantic journey, so when one lands they must prepare it for the return trip as quickly as possible.  It might take, for example:
*35 minutes to clean a plane
*15 minutes to refuel a plane
*10 minutes to load the passengers
*30 minutes to load the cargo

Assuming the above are done consecutively, minimum plane [[turnaround time]] is:
:35 + 15 + 10 + 30 = '''90'''

However, cleaning, refueling and loading the cargo can be done at the same time. Passengers can only be loaded after cleaning is complete. The reduced latency, then, is:
:35 + 10 = 45
:15
:30
:Minimum latency = '''45'''

The people involved in the turnaround are interested only in the time it takes for their individual tasks.  When all of the tasks are done at the same time, however, it is possible to reduce the latency to the length of the longest task. If some steps have prerequisites, it becomes more difficult to perform all steps in parallel. In the example above, the requirement to clean the plane before loading passengers results in a minimum latency longer than any single task.