The PERF page is where you set up the make-or-break phases of the flight. This guide walks through the TAKEOFF performance page — thrust reduction, flaps, FLEX temperature and V-speeds — and the APPR page that prepares your approach and landing.

1. The PERF page & flight phases

The PERF page stores the performance data for each phase of flight — takeoff, climb, cruise, descent, approach and go-around. The FMGS automatically advances through these phases as you fly, but the two you set up on the ground are TAKEOFF and APPR. Get these right and the aircraft flies the numbers for you.

2. Takeoff thrust: THR RED/ACC & TO SHIFT

THR RED / ACC

These are two altitudes, usually defaulting to around 3000 ft AGL. At the thrust reduction altitude (THR RED) the engines step back from takeoff to climb thrust; at the acceleration altitude (ACC) the aircraft lowers the nose to accelerate and retract flaps.

TO SHIFT

Used for intersection departures. If you're not starting from the very end of the runway, enter the distance (in metres) from the threshold to your actual takeoff point so the FMGS knows how much runway you really have.

3. Flaps, FLEX temperature & engine-out

FLAPS / THS

Enter your takeoff flap setting (Config 1, 2 or 3) and the THS (Trimmable Horizontal Stabilizer, i.e. pitch trim) value from your load sheet. Each flap configuration has its own maximum speed (VFE): Config 1 is limited to about 230 kt, tightening down to roughly 177 kt at Config FULL — always respect the placard for the setting you're in.

FLEX TO TEMP

A flexible (reduced-thrust) takeoff. You enter an assumed temperature higher than the real outside air temperature — for example 46°C — and the engines produce less than full thrust. When the runway is long enough, this saves engine wear and extends engine life without compromising safety.

ENG OUT ACC

The engine-out acceleration altitude — the altitude at which you'd level off to accelerate if you lost an engine after takeoff. It's normally set higher than the standard ACC altitude to clear obstacles on one engine.

4. Takeoff V-speeds (V1 / VR / V2)

The three takeoff speeds are computed from your weight, flap setting, runway and temperature. A typical set looks like this:

Speed	Meaning	Example
V1	Decision speed — the last point you can safely reject the takeoff	140 kt
VR	Rotation speed — begin raising the nose	142 kt
V2	Takeoff safety speed — the target if an engine fails	144 kt

Once you're airborne and past the acceleration altitude, the PERF page automatically advances to the CLB (climb) phase, where you can review or tweak the climb speed and any altitude constraints.

5. The APPR (approach) page

Before you start down, set up the approach on the PERF APPR page. The key fields:

QNH — destination airport pressure, from ATIS or ATC.
TEMP — destination airport temperature.
MAG WIND — wind speed and direction, referenced to magnetic north (not true north).
TRANS ALT — transition altitude, typically 18,000 ft.
Vapp — approach speed, computed automatically by the FMGS.
FINAL — the final approach segment.

Minima	Approach type	Meaning
MDA	Non-precision	Lowest altitude you may descend to without visual reference
DH	Precision (ILS)	Height to decide: continue to land or go around (≈ 0–700 ft)

Finally, set LDG CONF — the landing configuration, normally full flaps. With takeoff and approach both programmed, the PERF page has everything it needs to fly the profile.

Frequently asked questions