This article is from the Aviation FAQ, by Geoffrey G. Peck firstname.lastname@example.org with numerous contributions by others.
Aviation data changes on a day-to-day basis. Your best bet is to
use the comprehensive flight planner which is available from GTE
DUATS (see Q10). GTE has a staff which maintains the database on
a daily basis, and the flight planner is a thorough and complex
piece of software. It is also the only known flight planner which
has been tested and approved by the FAA; this was done as part of
the FAA-required DUATS review process.