Use the FMC to enter route and performance data, inspect CDU pages, and manage the active flight plan.
Captain CDU
Use cockpit_fmc_cdu to enter text and press CDU keys. Read fmc-cdu with read_group to inspect the current page and scratchpad. The control catalog lists the supported keys and displayed fields.
Line-select keys refer to physical positions. Their function depends on the current page; lsk-1l does not always select the same field. Check the page labels before pressing it. Read the scratchpad before typing and verify the destination field after selecting a line key.
Data Entry
- Obtain control of the CDU for the intended entry. Read the page title, relevant labels and values, and scratchpad.
- Confirm the intended page and field. Obtain the required value and format from the applicable procedure or mission data.
- Enter the value. Verify the scratchpad before selecting the associated line-select key.
- Read the destination field and any resulting message. Confirm the value was accepted in the intended field.
- If a modification is pending, review its scope before EXEC. Verify the accepted active result after execution.
If the page changes or CDU ownership changes, reacquire the page and field context before continuing. Do not clear a message without interpreting it. A displayed EXEC light is not authority to accept an unidentified modification.
Page and Position Coherence
Interpret displayed position values only after reading the page title and field labels. If the page changes, read it again before using those values. A position shown on a CDU page is not an independent position sensor.
Preflight Data
The source CDU preflight has three checks: Initial data — Set; Navigation data — Set; Performance data — Set. Use the applicable detailed page procedure to complete and verify each group. A successful text-entry or EXEC action alone does not satisfy the group.
Arrival and Approach
Before top of descent, make the required arrival-route modification and verify arrival RNP. During descent preparation, enter the applicable VREF on APPROACH REF and set or verify navigation radios. During approach, update RNP as needed. Retain the source conditions for each item.
Select one approach family: ILS, IAN or VNAV. Do not execute all landing families in document order. A displayed route is not an ATC clearance or confirmation that the scenery agrees with navigation data. Use the assigned clearance and navigation references.
General
Complete the preliminary, CDU, captain and first-officer procedures in the applicable ground configuration. Retain the side-specific requirements. A captain instrument or control does not satisfy an independent first-officer or standby check.
Use the assigned detailed panel procedures for Set, Check, Test and Pass requirements. Observe the specified result and restore the required operating configuration after each actual cockpit test. Do not operate a system merely because its control appears in the reference list.
Complete loading, performance preparation and the required equipment checks before progressing to the dependent departure procedures. Where an item requires an external inspection or crew adjustment, retain the assigned verification or explicit scenario exclusion.
Initial data — Set
Enter the required CDU initial data. Confirm the page and field before entry, then verify the accepted value.
Navigation data — Set
Enter the assigned route, runway and navigation procedure. Review the route and any modification before EXEC.
Enter the performance data for the actual aircraft loading and configuration. Verify the accepted weights, flap, trim and reference-speed data.
Controls and readings
See the current controls and readings for this system.
Detailed procedures
The following pages preserve each checklist item’s conditions, verification requirements and source identity.
Last modified on October 30, 2026
