Excursion
Excursion turns up in 2 fields: statistics, aviation. Here is what it means to the people in each one.
Excursion in statistics
Sudden departure of yield, defect counts or a key parameter from its normal band, big enough to trigger holds and an investigation.
Excursion is fab and plant shorthand for an abnormal event that moves a metric well outside its usual band, such as a particle spike on one tool, a yield drop on a group of lots or a parameter jump after a chemical change. Excursions start a familiar routine: hold affected material, define the scope, run commonality analysis across tools and steps, fix the cause and disposition the held lots. Teams track excursion count and lots affected as a key metric.
"We're calling it an excursion: 14 lots through etcher 6 since Thursday, all with the same bin 9 signature."
Excursion in aviation
A runway excursion is an incident where an aircraft veers off or overruns the runway surface.
An excursion occurs when an aircraft departs the paved surface of a runway or taxiway during the takeoff roll or landing rollout. This can happen due to crosswinds, mechanical failures, pilot error, or contaminated surfaces like ice and standing water. It often results in landing gear damage or getting bogged down in the surrounding mud.
"The airport is closed while recovery crews pull the 737 out of the mud after last night's excursion."