OPERATIONS MANUAL

Flight Instruments
ND Energy Management Circles:
• Circles are based on VNAV predictions (more accurate than
altitude range arc) to assist in idle descent planning when the
aircraft is off the planned route (for example, due to ATC vectors).
• Descent profile is based on predicted winds, predicted
temperatures, transition level, speed restrictions & transitions, antiice
schedule, aircraft gross weight, and other performance data.
• Applicable only with flaps up, gear up, and throttles at idle.
• End of descent is the waypoint position and altitude entered on the
FMC OFFPATH DES page.
• Circles are displayed when in MAP mode and when activated on
the FMC OFFPATH DES page during arrival.
For more information refer to OFFPATH DES Page in chapter FMS.
Target waypoint
The green triangle indicates the
center of the circles; that is, the
end of descent.
Speedbrake circle
The white dashed circle
indicates the top of descent for
idle descent with speedbrakes
fully extended to the flight
detent position. If the aircraft
is inside the white circle, it will
not reach the target altitude. If
the aircraft is halfway between
the white and cyan circle, the
target will be reached with
speedbrakes half extended.
A circle indicates the optimal
top of descent continuously;
for example, when the clean
aircraft starts descending at
the clean circle, the circle
will shrink and—in the ideal
case—follow the aircraft.
Clean circle
The cyan dashed circle indicates
the top of descent for idle descent
with speedbrakes retracted.
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