Setting Up the Approach (APPROACH REF)
PremiumintermediateAPPROACH REF for the ILS onto Heathrow 27R — a narrower page than the Airbus equivalent, and deliberately so.
What this scenario covers
APPROACH REF computes VREF from landing weight and flap setting, and that is very nearly all it does. QNH, minima and the approach mode itself live on the mode control panel and the altimeters, not in the box.
That division is a real design difference from the A320, where PERF APPR gathers QNH, wind, transition altitude, VAPP and minima in one place. On the 737 the approach setup is spread across the flight deck rather than concentrated in the CDU.
How it applies in flight ops
VREF plus a wind additive is the speed flown on final. The additive is a crew computation on the 737, which makes the approach briefing the moment it is agreed rather than something the box hands you.
The briefing is done before top of descent for the same reason as on any type: the descent and approach are the busiest phase of a short flight, and a page filled late is a page filled badly.
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Step-by-step: Setting Up the Approach (APPROACH REF)
- Open APPROACH REF from INIT REF INDEX. Press INIT REF (top-left page key), then LSK 5L for APPROACH.
APPROACH REF is the last CDU page you visit before landing. The FMC needs landing weight, flap setting and (optionally) wind to compute VREF. Real 737 SOPs brief APPROACH REF as part of the approach briefing — usually around top of descent.
- Enter landing gross weight 55.0 tonnes. Type 55.0 and press 1L.
Landing weight = takeoff weight minus fuel burned. For our EGLL → LSGG return, after the 480 nm trip and reserves, the 737 lands around 55 t. The FMC needs this to compute VREF — heavier aircraft = higher stall speed = higher VREF.
- Select FLAPS 30 for landing. Type 30 and press 2L.
Flap 30 is the 737-800's normal landing flap setting — best balance of approach speed and runway requirement. Flap 40 is for shorter runways and gives a lower VREF; flap 15 is for non-normal landings (overweight, single engine) and gives a much higher VREF. The page now shows VREF for all three flap options.
- Enter approach wind 270 magnetic / 10 kt. Type 270/10 and press 3L.
Wind from 270° with RWY 27 (heading 270°M) = 10 kt direct headwind. The FMC adds a wind correction to VREF: max(headwind/3, 5 kt) capped at +20. With 10 kt: 10/3 = 3.3 → below 5 kt floor → correction is 5 kt. Look at TGT VREF on the right column — that's your final reference speed bug.
What to take away
- APPROACH REF computes VREF from landing weight and flap.
- QNH and minima are set outside the CDU on the 737.
- The wind additive to VREF is the crew's, not the FMC's.
- Brief and set up before top of descent, not during it.