In response to such airline concerns, as well as to
various complaints about the limitations of the ATFM
system during the 1980s and 1990s, the FAA has been
engaged for the past 10 years in developing the Collaborative
Decision-Making (CDM) Program. After an
initial planning period of about five years, CDM was
fielded for the first time in 1998 in connection with the
FAA’s Ground Delay Programs (GDPs), which go into
effect whenever long air traffic delays are anticipated
at an airport due to poor weather or other reasons,
thus often necessitating ground holding. CDM marks
a truly fundamental innovation in the ATM system,
possibly the most important one in at least 30 years.
The three main elements on which it is based are: (a)
a dedicated data communications network (“CDMnet”),
which facilitates the continuous exchange of
information between the FAA and the airlines (plus
any other CDM participants) about the current and
near-future states of the ATM system; (b) the use of a
common database and a common set of software tools
by all CDM participants; and (c) the partial decentralization
of decision making. With respect to (c), it is
the FAA’s responsibility to forecast the capacity that
will be available at each part of the ATM system during
the relevant time horizon, as well as to allocate
this capacity among the individual airlines and the
other ATM system users. And it is the responsibility
of each individual airline to decide how it will use its
allocated share of capacity at each part of the system.
This is a somewhat simplistic description of what, in
practice, is a complicated process that employs several
types of distributed decision-making techniques,
such as rationing by schedule (RBS) and schedule
compression—see Wambsganss (1996) and Vossen et al.
(2003) for details.