ROUTE Page Basics

beginner
📍 Route: KJFK → EGLL⏱ ~3 minutes📊 8 steps🎓 Foundations

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

What this scenario covers

The RTE page takes the origin and destination, a flight number, and then the route itself as a series of via/to pairs: an airway and the point where you leave it, or DIRECT and a waypoint. It is a compact way of writing exactly what appears on the flight plan.

PERF INIT is its performance counterpart, carrying the weights, fuel and cruise level the FMC needs before it can predict anything. Between them, these two pages are most of a pre-flight.

How it applies in flight ops

Crews load a route the way it is written on the OFP, in order, and then verify it on LEGS — because RTE shows what you asked for and LEGS shows what the FMC built. The two are not always the same thing.

On the 737 there is a commit step: route entries are modifications until EXEC is pressed. That is a Boeing philosophy worth internalising early, and it gets its own scenario.

Start this scenario

Open the SimTuts 737 CDU trainer and select “ROUTE Page Basics” from the scenarios list to walk through it step-by-step on the simulated keypad.

Open trainer →

Step-by-step: ROUTE Page Basics

  1. Press the RTE page key to open the ROUTE page. This is where you enter origin, destination, and the company route.

    Origin and destination are 4-letter ICAO codes from your Operational Flight Plan (OFP) — the paperwork dispatch provides before every flight. KJFK = New York JFK, EGLL = London Heathrow. Getting this wrong means the FMS calculates the wrong route, fuel, and winds.

  2. Type KJFK into the scratchpad and press 1L to set the ORIGIN airport.

    Origin and destination are 4-letter ICAO codes from your Operational Flight Plan (OFP) — the paperwork dispatch provides before every flight. KJFK = New York JFK, EGLL = London Heathrow. Getting this wrong means the FMS calculates the wrong route, fuel, and winds.

  3. Type EGLL and press 1R to set the DEST airport.

    Origin and destination are 4-letter ICAO codes from your Operational Flight Plan (OFP) — the paperwork dispatch provides before every flight. KJFK = New York JFK, EGLL = London Heathrow. Getting this wrong means the FMS calculates the wrong route, fuel, and winds.

  4. Type KJFKEGLL01 and press 2L to enter the CO ROUTE — the company-stored route code.

    Company routes are pre-built flight plans stored in the airline's FMS database. Instead of entering every waypoint manually, you type a route code from the OFP. The dispatcher has already verified this route for airspace restrictions and NOTAMs.

  5. Type BAW178 and press 2R to enter the FLT NO (flight number).

    The flight number comes from the OFP and matches your ATC callsign. BAW = British Airways ICAO code, 178 = flight number. It's how controllers identify you on radar and how ACARS associates this FMS with the correct flight.

  6. Press 6R (ACTIVATE) to arm the route, then press the EXEC key to make it active.

    A 737 route is not flown the moment you finish typing it. ACTIVATE stages it, and the lit EXEC key commits it. That two-step is the FMC safety net: you can review a staged change before it becomes the active route. Every Boeing tutorial you watch passes through this sequence.

  7. Press 6R to move to PERF INIT, then type 52 and press 5L to set COST INDEX.

    Cost index is set by the airline, not the pilots — you find it on the OFP. It represents the ratio of time cost to fuel cost. A higher number means "time is expensive, fly faster." Typical values: 0–20 for fuel conservation, 30–60 for normal ops, 80+ for tight schedules.

  8. Type 39000 and press 1R to set CRZ ALT (cruise altitude).

    Cruise altitude comes from the OFP and is coordinated with ATC. It depends on direction of flight (semi-circular rule: eastbound = odd levels like FL350/FL370/FL390, westbound = even), aircraft weight, and wind. FL390 is near the ceiling and efficient for long-haul with low fuel load.

What to take away

  • RTE takes via/to pairs — airway then exit point, or DIRECT then waypoint.
  • PERF INIT supplies the weights and cruise level that all predictions depend on.
  • Enter on RTE, verify on LEGS. They can disagree.
  • Nothing is active until EXEC.

The rest of Foundations

Background reading

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