Descent Setup (DES + FORECAST)
PremiumadvancedPrepare the descent into Cleveland like a line crew: E/D altitude, target speed, forecast winds, and then take ATC's early descent with DES NOW.
What this scenario covers
The DES page carries the descent target speed and any speed restriction, and shows the end-of-descent altitude the profile is built to. The FORECAST page takes the descent winds, which materially change where the computed top of descent falls.
DES NOW is the answer to an early descent clearance: it leaves the computed path and starts down now, at a shallow rate, rejoining the path from above rather than diving to it.
How it applies in flight ops
VNAV descent planning is only as good as its inputs. Feeding realistic forecast winds is what makes the path credible; without them the aircraft plans against still air and arrives high or low depending on the day.
Being sent down early is routine in busy airspace, and it costs fuel — level flight at low altitude is expensive. DES NOW makes it a managed, shallow descent rather than a step down and a long level segment.
Fly this one with Premium
Everything about this scenario is on this page, steps included — reading it costs nothing and always will. What Premium adds is doing it: the CDU validates every entry as you make it, tells you when an entry was accepted but wrong, and saves your progress across devices.
Step-by-step: Descent Setup (DES + FORECAST)
- Set up the route: press RTE, type KORD and press 1L, then type KCLE and press 1R.
KORD → KCLE, the same Chicago–Cleveland sector as the constraints drill. The DES page is empty until a route with constraints exists — that is the point of this setup.
- Build the enroute leg: press 6L for RTE 2, type J60 and press 1L (VIA), type DJB and press 1R (TO), then press EXEC* (6R).
J60 to DJB (the Dryer VOR/DME west of Cleveland) puts a real waypoint between origin and destination — the fix the descent will be planned around.
- Enter the arrival constraint: press LEGS, type 240/10000B and press 2R on the DJB row, then press EXEC* (6R).
This LEGS constraint is where the DES page gets its E/D ALT. On the 737 the descent profile is built from the LEGS page constraints; the DES page displays and manages it, but does not own the data.
- Press the DES page key. The ECON PATH DES page appears.
E/D ALT now reads 10000 — taken from your DJB restriction. E/D ALT is display-only here: it is the altitude restriction of the end-of-descent waypoint, and the only way to change it is back on LEGS. ECON PATH is the default VNAV descent mode.
- Type .720/280 and press 2L to set TGT SPD.
A 737 descends at a Mach number until the indicated airspeed catches up, then holds the CAS — that is why the descent target is written Mach-first (.720/280), the mirror image of the climb's 280/.720.
- Type 240/10000 and press 3L to set SPD REST.
SPD REST shows the most restrictive applicable speed; dashes mean none is active. Setting 240 knots below 10,000 feet here keeps VNAV honest approaching the terminal area, slightly tighter than the standard 250.
- Press <FORECAST (6L). Confirm the transition level: type 180 and press 1L. Then enter the forecast descent wind: type FL240/270/40 and press 3L.
The forecast page takes wind direction/speed for up to three descent altitudes so the FMC can refine the path — here 270° at 40 knots at FL240, straight off the OFP wind summary. TRANS LVL defaults to FL180, the US standard; entering it confirms the value in large font.
- Press <DES (6L) to return. ATC: "Descend at pilot's discretion." Press DES NOW> (6R).
You are still short of the computed top of descent. DES NOW arms an early descent: the prompt stages the change (DES NOW ARMED) and the EXEC light illuminates. Nothing happens to the aircraft until you execute.
- Press EXEC* (6R) to execute. The title becomes ACT ECON PATH DES.
On execution the aircraft leaves cruise at about 1,000 fpm until it intercepts the computed ECON path, then follows the path down to cross DJB at or below 10,000 at 240 knots. ACT in the title means the descent phase is now active.
What to take away
- DES holds the descent speed and restriction; FORECAST holds the winds.
- Descent winds move the computed top of descent significantly.
- DES NOW starts an early descent that rejoins the path from above.
- Early descent is a fuel cost — managing it well is part of the job.