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FOMS Menu 436 (Minimum Time Track)

Note: The following descriptions represent the typical access and privileges afforded to users designated as Dispatch Managers/Supervisors. Users with dispatcher privileges will have limited access to a subset of the screens presented.

Given any two Airports or waypoints, this program will determine the least-time airways link between them using forecast winds at the specified flight level and time of departure, assuming of course, that there is in fact an airways link between the points in question.

To be properly effective, some restrictions must be taken into consideration:

  • The program looks for a route that lies in a reasonable proximity to the great circle track between the points.  Thus, it will not find a route that requires a turn of more than 85 degrees.
  • A complete airways link must exist. Thus, it is not possible to find an MTTA in areas where there are no airways, nor any direct legs that are stored in the Direct Legs data file.
  • This program does not take into account the climb and descent portions of the flight.

The initial screen calls for entry of the required parameters as follows.

Origin: You can use either an Airport or a waypoints the origin . If you choose an Airport, then the program will automatically assess the available SIDs, incorporating a SID into the route as applicable. ICAO, IATA, or FAA codes may be used to identify an Airport. If you choose to use a waypoint, enter the waypoint ID in the appropriate field. If there is no ambiguity, the country code and type data will be filled automatically, otherwise you can enter this data manually, or use the search function <?> to select from the available options.

Intermediate Waypoint #1: The program allows you to specify two intermediate waypoints via which the route must run. If you do not wish to specify an intermediate waypoint, simply press <Enter>. If you bypass the first intermediate point in this manner, the cursor will go directly to the Destination field.

Destination: Enter the destination, either as an Airport or waypoint, in the same manner as the Origin. If you select an Airport as the destination, the program will automatically consider and select the appropriate STAR.

Aircraft ID: Enter the aircraft ID.

RNAV: Indicate whether or not to use RNAV airways (<Y> for yes, <N> for no). The default value is Y.

Rules: Indicate whether to use rules-compliant routes (<Y> for yes, <N> for no). The default value is Y.

MTT: Indicate whether to do an MTT (no airways) instead of MTTA (using airways). Enter <Y> for MTT or <N> for MTTA. The default value is N.

Mach Number: Enter the cruise Mach number as a whole number, appropriate for the type of Aircraft. Do not enter any decimal point.

Flight Level: Select the flight level that should be used for winds.

Departure Date/Time: Enter a 6-digit group, indicating GMT departure time (DDHHMM format).

Hardcopy (Y/N): Enter Y if you wish to obtain a hardcopy. You will still obtain a screen report of the results.

Once the last entry has been made, you will be asked to confirm that everything is OK. Entering <N> will enable you to edit any of your inputs. When all entries are satisfactory, enter <Y> and the program will complete the analysis.

When the calculation of the MTTA is under way, the command line will show the distance remaining to the Destination as the program calculates the best available route option.

Final Results

If the program is able to find one or more routes between the selected waypoints, it will display them in order of increasing enroute time. The first line of the report gives the Estimated departure Time, Flight Level, and Mach Number.

Text

Description automatically generated

The first line of the best route option indicates average wind component, total enroute time, route distance and Great Circle distance. This is followed by the route description.

The final line of the report gives the intermediate Lat/Long coordinates of the Great Circle track, rounded to the nearest degree.

 

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