User manual

PFPX - Professional Flight Planner X
Aerosoft GmbH 2013
78 79
The runway that is designated the active runway for take-off depends
on the wind vector (direc-tion and speed) at the time of take-off, traffic
flow considerations and noise limitations. A SID may therefore be part
of a route specification.
When leaving an airway in order to land the aircraft may be required to
fol-low a standard terminal arrival route (STAR) and/or be vectored to
the land-ing runway.
Many oceanic crossings are not flown along pre-defined airways becau-
se of variable, strong winds. Across the North Atlantic Ocean, for exam-
ple, jet streams can be so strong at the altitudes typically flown by com-
mercial air-craft that flying with them or against them can make a great
difference to the length of the flight and therefore fuel consumption.
Oceanic tracks, for example, North Atlantic tracks, are declared daily to
take advantage of strong tailwinds and to avoid strong headwinds.
Occasionally, there will be a need to specify user-defined waypoints and
to route the flight via those waypoints. This can occur because of airs-
pace clearances due to diplomatic activity, volcanic eruptions, and gene-
ral safety issues.
Planning a lateral route between a departure airport and a destination
air-port has therefore to include the airways and, maybe, tracks to be
flown and optionally, the SIDs and STARs to be used.
Depending on airway restrictions, airspace structure and wind condi-
tions, the shortest route may not always be the optimum route.
Vertical navigation
Taking off from an airport, an aircraft is required to fly at certain altitu-
des to ensure safe separation from other aircraft. This will be specified
in a standard instrument departure (SID), if used, and may be overrid-
den by air traffic control. Climbing to an initial cruising altitude (top of
climb), the aircraft are separated vertically by being required to fly at
certain cruise levels, de-pending on the direction of travel. E.g. in the US
you should usually fly even flight levels using westbound airways, and
odd flight levels using eastbound airways.