Achieving reliable delivery times also requires very high mechanical and computer
reliability. Not only must the system be able to be in operation a very high percentage of
the time (which has been the immediate focus of attention at Denver), but it must also
operate accurately. However, sufficient accuracy is not easy to achieve, either in
reading information, or in managing it in the computer.
Any system of identifying bags makes mistakes in reading or transmitting information
about destinations. These happen for all kinds of reasons. The baggage handler may place the bag on the conveyor with the label hidden; the bag may have two labels, one
left over from a previous flight; the label may be dirty, out of the field of view or focus of
the laser reader; the laser may malfunction, and so on. Anyone who has watched
checkout clerks in a supermarket read bar codes with laser guns has seen that laser
readers do not work right all the time.