PERF: CALCULATE, TRANSFER AND VERIFY
PERF contains performance information. For takeoff, we first use the EFB calculation for the aircraft and departure we will actually use. The result depends on the engine variant, mass, runway entry point, surface condition, wind, temperature, pressure and intended configuration. These are the calculation's ingredients. Giving it a different mass or entry point produces an answer to a different takeoff problem, however tidy the result looks. [19, PDF pp. 6-8] [34, PDF pp. 8-9]
An intersection departure illustrates the point. Joining a runway partway along changes the starting point and available runway used by the calculation. Verify that choice carefully. The MCDU's TO SHIFT is the distance from the runway threshold to the takeoff starting point, in the specified units; it is a separate item from remaining TORA, the takeoff run available. The actual chart and preparation supply the appropriate information. [19, PDF pp. 6-8] [34, PDF pp. 8-9] [26, PDF pp. 125-128]
The calculation provides V1, VR and V2. V1 is the decision-speed reference used in stopping/continuing takeoff performance. VR is the speed reference for beginning nose-up rotation, and V2 supports the initial-climb schedule. Each has a separate field. Transfer the calculated values and read each accepted entry back against the result. We leave the numbers to the actual calculation, so there is no tempting example speed to carry into an unsuitable flight. [26, PDF pp. 125-128]
FLAPS/THS joins the takeoff flap configuration with the stabiliser-trim setting. Flaps are movable surfaces along the wing's rear edge; the trimmable horizontal stabiliser adjusts the horizontal tail for the required balance. Enter the correct information and later compare the actual aircraft settings with it. The useful check connects three things: the calculation/loading information, the accepted MCDU data and the aircraft's indicated configuration. [26, PDF pp. 125-128]
FLEX is a calculated reduced-thrust takeoff method using an assumed temperature. When the valid result calls for it, enter that specified temperature and verify the resulting request. Choosing an appealing temperature yourself would change the request without establishing the required performance. TOGA and FLEX are takeoff choices supported by the applicable calculation, not different ways to make a half-completed page look finished. [26, PDF pp. 125-128] [34, PDF pp. 8-9]
A runway, entry point, weather, mass or configuration change brings the affected work back through calculation and readback. The practical exercise shows which information to compare without inventing the operational figures. Take your time on this page during early flights. Understanding where the values came from is more useful than memorising a set of digits from somebody else's departure. [26, PDF pp. 125-128] [34, PDF pp. 8-9]
The reference for TO SHIFT is specifically the threshold-to-starting-point distance. The source also explains its use in climb-profile computation and its position-update role without GPS. Keep that reference separate from any runway length quoted elsewhere in the OFP or on a chart. [26, PDF pp. 125-128]
IN PRACTICE: PERF: transfer a valid takeoff calculation
Before you begin: Final load, actual runway/entry point, current conditions and intended configuration are known. Have the current EFB performance result beside the MCDU; this exercise supplies no invented V-speeds or FLEX temperature.
1. Check the calculation’s aircraft and load
Action. Open the EFB takeoff calculation and confirm the A320 CFM configuration and final mass. Check that the selected aircraft profile is the one loaded in the simulator.
Check. The calculation belongs to this aircraft and loading state, not another family member or an earlier version of the load. [26, PDF pp. 125-128] [51]
2. Check runway, entry point and conditions
Action. Confirm the actual runway and intersection/full-length entry, surface condition, wind, temperature, pressure and intended configuration. Include the applicable pack/anti-ice choices in the performance assumptions.
Check. The available runway and conditions used by the calculator agree with the intended departure. A change of entry point has not left a full-length result in use. [26, PDF pp. 125-128] [14, PDF pp. 1063-1064]
3. Review the result before copying it
Action. Run the calculation and inspect its validity and any limiting information. Resolve incorrect inputs or an unsuitable result before transferring figures; do not treat the presence of numbers as approval to depart.
Check. You have a usable result with understood assumptions. The selected takeoff thrust/configuration is supported by that result. [26, PDF pp. 125-128] [14, PDF pp. 1063-1064]
4. Verify the PERF runway
Action. Press PERF and open TAKE OFF. Compare its runway with the departure selected in F-PLN and the EFB calculation. Resolve a disagreement before entering speeds.
Check. Route, performance page and calculation refer to the same runway. A previous runway’s data have not survived behind the new route selection. [26, PDF pp. 125-128] [26, PDF pp. 142-165]
5. Transfer and read back the speeds
Action. Enter the calculated V1, VR and V2 into their respective fields, then read them back individually against the current result. Check the entry accepted by the MCDU, not only the scratchpad you typed.
Check. Each speed matches the calculation and occupies the correct field. No teaching-example speed has been substituted for the actual result. [26, PDF pp. 125-128]
6. Transfer configuration and thrust data
Action. Complete FLAPS/THS from the calculated configuration and trim information. Enter the calculated FLEX temperature only when FLEX is the valid selected thrust method. Verify the resulting configuration/thrust entries against the EFB result.
Check. The page represents the intended flap/trim and thrust preparation. A FLEX field has not been filled with an arbitrary temperature to make the page look complete. [26, PDF pp. 125-128]
7. Review the remaining departure parameters
Action. Check transition altitude, thrust-reduction/acceleration and engine-out acceleration entries against the actual procedure and applicable operating assumptions. For an intersection departure, check TO SHIFT as the distance from the runway threshold to the start-of-takeoff point, in the configured M or FT units; it is not the remaining takeoff run available.
Check. Stored defaults have received a real check. The runway-entry information and departure parameters are consistent with the flight being prepared. [26, PDF pp. 125-128]
8. Set a clear change trigger
Action. After any relevant runway, entry-point, weather, loading or configuration change, recalculate and revisit the affected MCDU entries. Complete the comparison again before treating takeoff preparation as finished.
Check. One coherent result is in use. The aircraft is not carrying a mixture of new route data and old takeoff figures. [26, PDF pp. 142-165] [14, PDF pp. 1063-1064]
Complete when: The takeoff page agrees with one valid calculation for the actual departure. A subsequent relevant change sends the affected preparation back through the same calculation and readback.