Here, regional aircraft leave US service youngest, wide-bodies oldest and narrow-bodies in between. Every median is later if only aircraft reported as withdrawn count, so the result depends on how an exit is counted.
What this shows: The chart plots Narrow-body, Wide-body and Regional on a vertical axis of Survival probability (%).
Conditions and method
Status: descriptive (the medians depend on how an exit is defined; counting only aircraft last filed as withdrawn puts every median later).
One curve point per age: the share of aircraft still filed at the year-end census at that age. An aircraft is one airframe under every tail number it was filed with, and a passenger aircraft converted to a freighter has not left. The median is the first age at which half are no longer filed. Under the six other rules tried for identifying an aircraft and dating its entry and exit, the medians move by no more than a year: narrow-bodies 24 to 25, wide-bodies 26 to 27 and regional aircraft 18 to 19 years.
Counting only aircraft last filed as withdrawn, the median age at leaving is 31 years for narrow-bodies (25 as plotted), 31 for wide-bodies (27) and 28 for regional aircraft (19).