"Jose" wrote in message
.. .

It doesn't. It prevents the last digit from being cut off =unawares=. It
acts as a checksum of sorts. If all runways are two digits, then any
transmission missing a digit is suspect. If some are one and some are
two, then there are some cases where an error would not be noted; this is
especially the case with runway 2-20, both of which exist on most airports
for which one exists.


Wouldn't the gap in the transmission do that?