Boeing 737 CDU Practice Scenarios

A tour of the 737 CDU with nothing to type: where each page lives, so that later scenarios can say "go to LEGS" and mean something.

RTE and PERF INIT — the two pages every 737 flight is built on. Program a JFK to Heathrow route from empty.

Before the FMC will do anything useful, the inertial reference system has to know where it is. POS INIT is where you tell it.

The single biggest difference between the Boeing CDU and the Airbus MCDU: on the 737, nothing you type takes effect until you press EXEC.

Before an approach, real crews verify the navaids they are about to use. REF NAV DATA is where you look them up.

London to Paris on the 737: RTE 1, RTE 2, PERF INIT and TAKEOFF REF, the complete short-haul setup in one sitting.

Phoenix to Las Vegas: enter the route, then program a departure and an arrival from the DEP/ARR page.

The error message every 737 pilot meets on the RTE page — INVALID ENTRY — has three quite different things to tell you, and it will not say which.

The box prompts on the LEGS page are a route discontinuity. Here is what the FMC is asking for and how to close the gap.

The destination is wrong on the RTE page. Overwriting a field you already filled is a distinct skill from filling it.

At the gate with the OFP for a Geneva sector: weights and fuel on PERF INIT, on one page where the Airbus uses two.

Takeoff flap and V-speeds on the TAKEOFF REF page — the three numbers that turn a runway analysis into a takeoff you can fly.

Reduced-thrust takeoff, Boeing's way: the assumed temperature method. Tell the engines it is hotter than it is and they produce less thrust.

Three cost index values on PERF INIT — 0, 30 and 80 — and the speed schedule changes under you.

Thirty minutes into the sector: read the predicted destination fuel on PROGRESS, then reconcile PERF INIT against what the gauges actually say.

Westbound over the Atlantic at FL340 and getting lighter. Read OPT and MAX on the CRZ page, then step to FL360.

"Direct OCK" on descent: stage the waypoint on LEGS, recover from a mis-hear, then EXEC it.

Halfway to Paris, ATC closes it for weather. Change the FMC to Brussels the way a line crew would, under time pressure.

"Cross DJB at or below one-zero thousand, two-four-zero knots." That clearance becomes a LEGS entry with a B suffix.

Cleveland approach is saturated and you are going into the hold at DJB. Build the pattern with the HOLD key, then get out of it again.

Prepare 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.

Level at FL290 with Cleveland ahead, cleared to 10,000 — and the aeroplane will not start down. Work the classic triad on the CDU: find the floor the FMC is holding, release the constraint trapping the descent on the LEGS page, then take the late descent with DES NOW and read VNAV PATH against VNAV SPD.

APPROACH REF for the ILS onto Heathrow 27R — a narrower page than the Airbus equivalent, and deliberately so.

JFK to Boston: about 185 nautical miles, no airway needed, and therefore a pure SID-and-STAR drill.

Los Angeles to New York on the 737: RTE, a LAX departure, J146 across the country, and a JFK arrival.

The northern transcon: Seattle to New York via J70, the same skills as J146 on a different corridor.