Top of Climb and Top of Descent Planning in Your Simulator
Vertical profile management separates smooth airline-style sim flights from endless step corrections on approach. NG ROUTE marks Top of Climb (T/C) and Top of Descent (T/D) on the map and ties them to the terrain and cruise level you selected. Here is how to turn those markers into cockpit actions.
What T/C represents
T/C is the point along track where your aircraft should reach the suggested cruise flight level assuming a normal climb rate after takeoff. It is computed from distance, assumed climb speed, and altitude delta — not from a specific SID gradient.
If you fly a departure procedure with a published level-off at 5,000 or 10,000 feet, your real T/C occurs later than the marker. That is expected. The marker describes the en-route portion once you are on the airway structure.
What T/D represents
T/D is where descent should begin to arrive near the STAR or approach gate at a reasonable altitude. Beginning descent on time prevents the “dive and drive” habit of dropping thousands of feet per minute at the last fix.
In Airbus managed mode, crossing T/D with DES armed lets the FMGC start a calculated profile. In Boeing aircraft, use VNAV PATH or manual vertical speed with the marker as a cross-check.
Terrain awareness
The elevation chart under the map shows maximum terrain along route. Compare cruise altitude minus terrain peak for clearance margin. If ridges approach your level, plan an earlier climb or later descent segment — especially in places like the Alps, Rockies, or Andes.
Energy management tip
Descend with a plan: idle thrust, spoilers only if needed, and a target of intercepting the glideslope from below on ILS. Starting descent at T/D with 280 kt clean configuration usually beats rushing later with speed brakes fully deployed.
SID and STAR interaction
NG ROUTE exports en-route airways without embedding terminal procedures. Your actual T/D may move if ATC vectors you wide. Recompute mentally: if you are still at FL350 when 80 NM from destination, you are probably late.
Practice exercise
- Pick a 400 NM route with terrain below 10,000 feet.
- Note T/C and T/D distances from the nav log.
- At T/C, confirm altitude within 1,000 feet.
- At T/D, arm descent and target 250 kt by 10,000 feet.
- Log how many times you needed corrections before approach.
Repeat the same city pair until you need zero power-idle surprises inside 20 NM final. That repetition builds the automation trust long-haul sim pilots rely on.