F
Furthermore, under the supervision of air traffic control, aircraft flying in
controlled airspace must follow predetermined routes known as airways, even
if such routes are not as economical as a more direct flight. Within these
airways, aircraft must maintain flight levels, specified altitudes usually
separated vertically by 1000 or 2000 feet (305 or 610 m), depending on the
route being flown and the direction of travel
When aircraft with only two engines are flying long distances across oceans,
deserts, or other areas with no airports, they have to satisfy additional ETOPS safety rules to
ensure they can reach some emergency airport if one engine fails.
Producing an accurate optimised flight plan requires millions of calculations, so commercial
flight planning systems make extensive use of computers (an approximate unoptimised flight
plan can be done by hand in an hour or so, but more allowance must be made for unforeseen
circumstances).
When computer flight planning replaced manual flight planning for eastbound flights across
the North Atlantic, the average fuel consumption was reduced by about 1,000 pounds per
flight, and the average flight times were reduced by about 5 minutes per flight.
Some commercial airlines have their own internal flight planning system, while others employ
the services of external planners.
A licensed flight dispatcher or flight operations officer is required by law to carry out flight
planning and flight watch tasks in many commercial operating environments (e.g., US FAR
§121,Canadian regulations).
These regulations vary by country but more and more countries require their airline operators
to employ such personnel.
Overview and basic terminology
A flight planning system may need to produce more than one flight plan for a single flight:
•
summary plan for air traffic control (in FAA and/or ICAO format)
•
summary plan for direct download into an on-board flight management system
•
detailed plan for use by pilots
A - Z of Flight
July 2017
www.alliance-airways.net
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