The IFR plan is finished the way the VFR plan was, with two differences: most of the geometry is printed rather than measured, and a flight management computer will re-do every calculation in flight. This lesson completes the manual plan first, top of climb to top of descent, and then weighs what the computer adds and where it quietly fails.
Frequencies and aids for the IFR plan
The en-route chart publishes the radio environment: the control centres' sector frequencies and call signs in boxes drawn against their sector boundaries, and every radio-navigation aid's frequency and identifier in its own data box, ready to be copied into the plan in route order, so the flight always knows whom to call next and what to tune next.
Filling the plan
The plan lines are completed with the courses, distances and frequencies copied from the charts, and the SID and STAR to be flown or expected are chosen from the runway and direction of flight, briefed with their alternatives. One conversion deserves care: the en-route chart's printed tracks are already magnetic, but a leg the planner measures personally (a DCT, or a chart-plotted segment) comes off the meridian as a true course and needs the variation applied: easterly variation subtracts (east is least), westerly adds. The rest is the VFR module's craft unchanged:
TAS — from the performance CAS, corrected for altitude and OAT.
WCA and ground speed — crosswind times 60 over TAS, held into wind; the along-track component sets the ground speed.
Times — leg and accumulated, run to the destination and on to the alternate.
TOC and TOD
Two positions turn the plan three-dimensional. The top of climb sits where the climb ends: height to gain divided by the rate of climb gives the time, and time multiplied by the climb ground speed gives the distance from departure. The top of descent is the same arithmetic run backwards from the destination: height to lose over the rate of descent, times the descent ground speed, measured back along the route from the fix the descent must end at.