DCA (Washington) changed its 00-18 to 01-19 a few years ago.


Mxsmanic wrote:
Thomas Borchert writes:

Let's assume Runway23. It's designated when the real direction is 225.
Now, how much has the real direction to change upwards for it to be
designated 24?

Eleven degrees.

However, if it is designated 22 (it can be 22 or 23 if the real
heading is 225), an increase of only one degree in its true magnetic
heading would require a change to 23.

The rule is to round the true magnetic heading to the nearest multiple
of ten and then drop the last digit. If the true heading ends in 5,
you can round up or down (there is no preference).