> For the complete documentation index, see [llms.txt](https://docs.flightsim-studio.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.flightsim-studio.com/e-jet-series/mcdu-guide/perf.md).

# PERF

Press **PERF** to open **PERF INDEX 1/2**.

| LSK | Label     | Page                             |
| --- | --------- | -------------------------------- |
| 1L  | PERF INIT | Performance initialization 1/3   |
| 1R  | TAKEOFF   | Takeoff speeds and configuration |
| 2L  | DEP LIM   | Departure limit / VNAV capture   |
| 2R  | CLIMB     | Climb predictions                |
| 3L  | CRUISE    | Cruise predictions               |
| 4L  | DESCENT   | Descent predictions              |
| 4R  | APP SPD   | Approach speeds                  |
| 5L  | LANDING   | Landing                          |

{% hint style="info" %}
**DES FORECAST**, **GA LIM**, **FUEL MGT**, and **EO RANGE** are shown on the index but are not implemented.
{% endhint %}

Thrust rating is a separate function key: TRS.

## PERF INIT (1/3–3/3)

**1/3** — TAIL #, PERF FACTOR, FUEL RESERVE, TO/LDG FUEL, ALTN FUEL. **SEND REQST** imports SimBrief performance (check that aircraft weight matches the OFP).

**2/3** — CRZ ALT, STEP INC, CRZ WINDS, ISA DEV, ZFW, FUEL, TO CG, GROSS WT.

**3/3** — climb / cruise / descent speed modes and COST INDEX. Speed-mode pages include **ECON**, **LRC**, **MAX SPD**, **MAX END**, and **VMO/MMO**.

{% hint style="danger" %}
**CONFIRM INIT** (LSK **6R**, inverse white) appears on **PERF INIT 3/3** once the required initialization fields are complete (cruise altitude, fuel, ZFW, takeoff CG, and gross weight). You **must** press it to confirm performance initialization.

Without **CONFIRM INIT**:

* The vertical profile (TOC / TOD) is **not** calculated
* VNAV path and the MFD vertical profile stay unavailable
* **PERF DATA** pages show blank values

After any change to PERF INIT data (weights, cruise altitude, fuel, winds, SimBrief import, etc.), **CONFIRM INIT** appears again and must be pressed before the FMS recalculates the vertical profile.
{% endhint %}

After confirmation, LSK **6R** shows **PERF DATA** and opens the **PERF DATA** pages.

## PERF DATA (1/3–3/3)

Reached from **PERF INIT 3/3** via **PERF DATA** (LSK **6R**) after **CONFIRM INIT**, or from LSK **6L** on any PERF DATA page back to **PERF INIT**.

**1/3** — cruise altitude, ceiling, step increment, and destination / alternate ETE, ETA, distance, fuel required, fuel remaining, and gross weight.

**2/3** — cruise wind, tailwind component, and destination fuel preflight vs. updated plan (with difference after takeoff).

**3/3** — fuel reserve and destination fuel plan comparison (preflight vs. live EFOB after takeoff).

LSK **6R** on PERF DATA links to the next workflow page (**DEPARTURE**, **TAKEOFF**, or **CLIMB**, depending on flight phase and whether departure runway and V-speeds are set).

## TAKEOFF

V1, VR, V2, VFS, flaps, pitch trim, and TO pitch. Links to **TO INIT**, **DEP LIM**, **CLIMB**, and **LANDING**.

**TO INIT** — runway heading, GW, pressure altitude / baro, elevation, slope, wind, runway condition (DRY / WET / CNTMNTD). **SEND REQST** can pull takeoff data from the OFP.

**TO DATASET MENU** is reached from TRS LSK 6R (TO-1/2/3, ATTCS, REF ECS, REF A/I, FLEX).

## DEP LIM

Speed limit, AFE, **VNAV CAP** (default 800 ft AFE — altitude where VNAV captures after takeoff), and engine-out bank.

## CLIMB / CRUISE / DESCENT

Prediction pages (TOC / TOD / BOD, speed command, transition altitude). **DES NOW** is available in descent when a path descent can be started early.

## LANDING and APP SPD

Landing initialization, landing page, and **APPROACH SPEEDS** (fixed / green-dot / flap speeds).

**TEMP COMP** is entered from LANDING INIT (LSK 5R) after destination OAT is set. Full procedure: FMS Temp Compensation.