Calculating Great Circle Flight Times (Basic)
(See also how to Calculate with Flight Planning.)
The following example is for a 700NM leg
Cruise Speed = True Airspeed
- The system would utilize the 300 NM distance profile because it is the next lowest distance from the leg distance.
- Considering that it is using the 300 NM profile, the calculation would have the aircraft climbing all the way to 39,000 ft.
- To figure out the time to climb to 39,000 ft and descend back to ground, it will iterate through each distance profile below the one utilized as follows:'
Climb = Indicated Airspeed
- 0 to 8,000 ft = 8000 ft at 2900 fpm = 2.8 minutes
- 8000 to 15,000 ft = 7000 ft @ 2900 fpm = 2.4 minutes
- 15,000 – 39,000 ft = 24,000 ft @ 2900 fpm = 8.3 minutes
- Total time to climb is 2.8 + 2.4 + 8.3 = 13.5 minutes
Descent = Indicated Airspeed
- 39,000 to 15,000 ft = 24,000 ft @ 3100 fpm = 7.7 minutes
- 15,000 to 8,000 ft = 7000 ft @ 3100 fpm = 2.3 minutes
- 8.000 to 0 ft = 8000 ft @ 3100 fpm = 2.6 minutes
- Total time to descend is 7.7 + 2.3 + 2.6 = 12.6 minutes
- Total = 26.1 minutes
- Ground speed it calculated for the climb and descent based on the climb/descent speeds for the 300 NM configuration and winds for the lat/long of the top of the climb and start of descent.
- Ground speed is calculated at four additional points along the flight path considering winds at each lat/long.
- An average is calculated across all 6 ground speeds and utilized for the final flight time calculation.
Calculating with the Enhanced Flight Time Setup
If Calculate with Flight Planning is enabled for an aircraft, additional options will be available for each distance profile to indicate which cruise profile to use. The options in the drop down will vary based on the aircraft type but common options will be Long Range Cruise, Max Cruise Speed and Standard. Long Range Cruise, for example, will optimize the fuel economy for the flight calculations while Max Cruise Speed will favor maximum performance. If Standard is selected, a fixed cruise speed will be maintained through the flight using the manufacturer recommended speeds. Finally, if Custom is selected, an additional field will be displayed which allows the user to enter a custom fixed Mach value (ex. If the desired speed is Mach 80, then 80 should be entered).
Things to Know:
- If a flight leg reverts to Great Circle, it will use the Basic Avianis Flight Time Configuration values from the table.
- If the flight planning module is enabled and Great Circle is selected as a cruise profile, it is using the enhanced Great Circle data (Manufacture Performance data, point to point and winds).
- 'Use Winds' will affect the calculated Flight Time
- 'Taxi Time' will affect block / leg / trip time. If a Taxi Time is entered in the Aircraft Profile it will override the time provided in the trip configuration settings. (Note: Use time in decimal format.)