Introduction
A Simple Route
Step Climb
RVSM Transitions
A Real Flight Plan

This is a quick introduction to filing and reading ICAO Flight Plans. This Section will deal mostly with Item 15 on the ICAO FLIGHT PLAN, and in our simulated world the Route Section in SquawkBox and the Flight Strip of the Radar Client.

The main reason for filing a flight plan and route is the pilot is informing the ATC units along the way his/her requests to complete the journey, this will include the speed, cruise level waypoint and airways to be flown. And one other major reason in non-Radar equipped regions (these are becoming much less in the real world and non existent in the simulated environment) if you haven't arrived at your destination in the allowed time limit, the emergency services will have a good idea where to look for you. Flying isn't as easy as jumping into your car and going from point A to B.

The Basic format for a f/p route is;
Waypoint RouteDesignator Waypoint DCT Waypoint RouteDesignator.... etc.
in some circumstances were a Waypoint doesn't cross from a designated route the letters "DCT" meaning direct are used (there are no waypoints in the world with this call sign). Some countries do not allow deviation from designated routes, or if allowed for short distances only.

A simple Flight Plan between LTBA(Atatürk) and LGAV(Venizelos) might look like this
BIG VG8 AMANI UG8 KEPIR
This simply translates to after takeoff the pilot will fly to BIG (depending on the pilot's and ATC's choice this can be a vector or SID departure, if a pilot knows the active runway at departure time this might be included in the route as BIG1S BIG VG8.... same goes for arrival ...UG8 KEPIR KEPIR1A. Remember a pilot has the choice of refusing a SID/STAR and may request vectors).
On a/w VG8
BIG to AMANI
from here they will join a/w UG8 and continue along the waypoints on a/w UG8
AMANI to LSV to OLIDA to KEPIR
the complete list of waypoints do not have to be specified as shown in the route above but if included this will also be acceptable, but will usually very long to fill and read and is not good practice.

Pilots usually do not stay at the initial requested speed and cruise level, they change the speed and cruise level during the duration of the flight this is for many reasons. On long haul flights e.g. LTBA-KJFK a fully loaded A340 would not be able to climb to the most efficient cruise level just after takeoff, because of the weight of the extra fuel, but as the flight progresses and the fuel is burnt off the pilot will periodically climb to a higher flight level until he reaches his most efficient cruise level. Another reason for cruise level changes can be for favourable winds, resulting in shorter flight times and of course lower fuel consumption. For these reasons the speed and cruise level changes are included in the route section of the flight plan.

Speed and Level change format is:
RouteDesignator Waypoint/SpeedLevel...
either if a speed or a cruise change is requested both are supplied.

Cruise Climb format is:
RouteDesignator C/Waypoint/SpeedLevelLevel...
Begins with the letter "C" and waypoint, the speed is the intended cruise speed to be maintained during the cruise climb and the layer of the two levels during the climb. If the second level is specified by the letters "PLUS" this indicates the level above which the cruise climb is planed for.

The speed and level formats should be quite obvious depending in what part of the world you are e.g. Km/h and metric cruise levels are used in Russian Federation Countries.

A route from LTBA(Atatürk) to EGLL(Heathrow) might look like this:
N0440F300 FENER A16 VADEN UL610 BATTY UL608 LOGAN
The initial speed and cruise level (N0440F300) will not be usually included in the route as this is specified elsewhere in SB. If a climb was requested, the route may appear like this:
FENER A16 VADEN UL610 ABETI/M075F340 UL610 BATTY UL608 LOGAN
if the waypoint where a speed/level change is required the following airway designator will be supplied, even if on the same route designator UL610 in this case.

A long haul route from LTBA(Atatürk) to KORD(Chicago) might be similar to this:
N0460F280 FENER A16 VADEN UL610 C/TIMOT/N0455F300F320 UL610 BATTY UL608 C/BUB/M080F340PLUS UA24 NIK UL610 LAM/M080F360 UB29 CPT UG1 STU UN546 DEVOL UN544 DOGAL/M081F360 54N020W/M081F370 55N030W 55N040W/M081F390 54N050W CARPE REDBY YNA YRI YXI ECK J94 FNT PMM4

Since the introduction of RVSM (Reduced Vertical Separation Minima) in Europe, the pilot flying in and out of RVSM airspace will require a cruise level change to comply with correct Flight Levels for the airspace in which they are operating.

A Route from OEJN(Jeddah) a non-RVSM airspace to LTBA(Atatürk) a RVSM approve airspace, there will be a need for a transition between the two:
N0460F310 EPLOM A424 PMA B544 TUSYR/M080F340 VB36 GAZ DCT TOROS VW75 BAG UL614 YAA
In the above route the initial cruise level is FL310, this is the correct level for non-RVSM airspace at TUSYR the entry/exit point into RVSM, the level requested is FL340, also correct for RVSM airspace (see cruise levels for more). The speed and level change format is exactly the same as for step climb.

A real world ICAO coded flight plan contains much more information than what we are usually accustom to in the simulated environment, here's an example.

CODED ICAO FLIGHT PLAN

(FPL-N100A-IG
-GLF4/M-SXWHIGRY/S
-KEWR2315
-N0465F370 DCT MERIT DCT HFD J42 BOS DCT VITOL/M080F410 N27A
 NANSO/N0459F410 N27A RAFIN/M080F410 DCT 45N050W 47N040W 49N030W
 49N020W DCT BEDRA/M080F410 UN491 TAKAS/N0459F410 UN491 VMP UL851
 MELKO UM606 BLM DCT
-LSZH0652 LSGG 
-EET/KZBW0003 KZNY0040 CZQM0041 CZQX0141 EGGX0342 EISN0457
 EGTT0531 LFRR0534 LFFF0606 LFEE0631 EDFF0645 LSAZ0646
 RAFIN0156 45N050W0204 47N040W0253 49N030W0342 49N020W0432 
 REG/N100A SEL/GQEK DOF/020214 RMK/TCAS EQUIPPED AGCS EQUIPPED)
KZNYZQZX KZBWZQZX CZQMZQZX CZQXZQZX EGGXZOZX EBBDZMFP LFPYZMFP

This can be decoded as
(FPL-N100A(Aircraft Call Sign or Flight Number)-I(FR)G(eneral flight)

-GLF4(Gulfstream 4)/M(edium Wake Category)-Equipment/S(transponder equipment do not confuse with equipment suffix)

-Departure Airport and Time in Zulu
-Route N0465F370 (KTAS465 initial speed and FL370).... at VITOL/M080F410 a climb to FL410.. etc
-Arrival Airport (Zurich) and duration of Flight 6hours and 52minutes Alternate Airport (Geneva)
-Estimated enroute time for crossing FIR regions... EGTT0531 London FIR in 5hours and 31minutes and other info the pilot wants you to know.

(Routes specified may have changed since the writing of this article.)