Oddball question, but I was looking through my boarding passes and bag tags for CO for the past year, and the though occurred to me...
How long before a reservation system reuses PNR numbers, and are PNR numbers used in sequence?
I had assumed that it would be a ~1 year period, but looking at my trip back in march (Continental PNR VKX66Q) and the trip I'm leaving for on Monday (CO PNR V90N**), if PNRs are used in sequence, it would appear that it was more like 6 months).
Also, why is it that CSRs seem suprised when I know the PNR number for my itin but not the flight numbers*...
* (For example, I know I'm going to IAH at about 3:00 with V90N** on Monday, but don't ask me what flight that is)