Page 142 - Planning and Design of Airports

Air Traf fic Management 111

FAA for use in the United States. The separation rules are prescribed
for IFR operations and these rules apply whether or not IMC condi-
tions prevail. Minimum separations are a function of aircraft type,
aircraft speed, availability of radar facilities, navigational aids, and
other factors such as the severity of wake vortices [3].

Vertical Separation in the Airspace
The minimum vertical separation of aircraft outside of the terminal
area from the ground up to and including 41,000 ft AMSL is 1000 ft.
In 2005, vertical separation minimums above 29,000 ft AMSL were
reduced from 2000 to 1000 ft under the reduced vertical separation
minima (RVSM) program. Implementation of this program allowed
for additional jet routes thereby increasing the capacity within the
NAS. Within a terminal area a vertical separation of 500 ft is main-
tained between aircraft, except that a 1000-ft vertical separation is
maintained below a heavy aircraft.

Assigned Flight Altitudes
To formalize the separation of air traffic in the airspace, air traffic
control assigns flight altitudes to aircraft based on their direction, or
more precisely magnetic heading, of flight, and whether or not they
are flying under VFR versus IFR rules.
Aircraft flying under IFR are typically assigned altitudes of odd-
thousand feet (i.e., 3000 ft, 5000 ft, etc.) AMSL while on an easterly
heading (magnetic compass heading of 0° to 179°) and even-thousand
feet (i.e., 4000 ft, 6000 ft, etc.) while on a westerly heading (magnetic
compass heading of 180° to 359°). Between 29,000 ft AMSL (FL 290)
and 41,000 ft AMSL (FL 410), aircraft are assigned a flight level of
either FL 290, FL 330, FL 370, or FL 410 when traveling on an easterly
heading, and either FL 310, FL 350, FL 390 when traveling on a west-
erly heading. If an aircraft is RVSM certified, it may be assigned an
RVSM altitude of FL 300, 320, 340, etc. between FL 290 and FL 410.
Aircraft flying under VFR above 3000 ft AMSL are typically
assigned altitudes of odd-thousand feet plus 500 ft (i.e., 3500 ft, 5500 ft,
etc.) while on an easterly heading, and even-thousand feet plus 500 feet
(i.e., 4500 ft, 6500 ft, etc.) while on a westerly heading (magnetic com-
pass heading of 180° to 359°). Above 29,000 ft (FL 290), VFR traffic is
assigned every-other even or odd thousand (FL 290, FL 330, etc. if
traveling on an easterly heading, and FL 320, FL 360, etc. if traveling
on a westerly heading). It should be noted that above FL 180, all traf-
fic is required to be on an IFR flight plan.

Longitudinal Separation in the Airspace
The minimum longitudinal separation depends on a number of fac-
tors. Among the most important are aircraft size, aircraft speed, and
the availability of radar for the control of air traffic. For the purposes