B737 Mode Control Panel

1. Autothrottle (A/T) ARM Switch

  • ARM – Arms A/T for engagement. Magnetically held at ARM. A/T engages automatically when the following DFCS modes are engaged:
    • LVL CHG
    • ALT ACQ
    • V/S
    • VNAV
    • ALT HOLD
    • G/S capture
    • TO/GA.
  • The indicator light illuminates green when the A/T ARM switch is in the ARM position.
  • OFF – Disengages A/T and prevents A/T engagement.

2. Changeover (C/O) Switch

  • Push –
    • Changes IAS/MACH display between IAS and MACH,
    • Automatic changeover occurs at approximately FL260.

3. MCP Speed Condition Symbols

  • Overspeed or underspeed limiting symbol appears when commanded speed cannot be reached.
  • Underspeed limiting (flashing character “A”) –
    • Minimum speed
  • Overspeed limiting (flashing character “8”) –
    • Vmo or Mmo limit
    • Landing gear limit
    • Flap limit.

4. IAS/MACH Display

  • Displays speed selected by IAS/MACH selector
  • Display is blank when:
    • VNAV mode engaged
    • A/T engaged in FMC SPD mode
    • During 2 engine AFDS go–around
  • Displays 100 knots when power is first applied
  • Display range is:
    • 100 KIAS – Vmo in 1 knot increments
    • .60M – Mmo in .01M increments.

5. N1 Switch

  • Push – light not illuminated
    • Engages A/T in N1 mode if compatible with DFCS modes already engaged
    • Illuminates N1 switch light
    • Annunciates N1 autothrottle mode.
  • Push – light illuminated
    • Deselects N1 mode and extinguishes switch light
    • Engages autothrottles in ARM mode.

N1 Mode

  • A/T maintains thrust at N1 limit selected from FMC CDU. N1 mode engaged manually by pushing N1 switch if N1 mode is compatible with existing DFCS modes. N1 mode engages automatically when:
    • Engaging LVL CHG in climb (except during inhibit period for 2 1/2 minutes after lift-off)
    • Engaging VNAV in climb.

6. SPEED Switch

  • Push – light not illuminated
    • Engages A/T in SPEED mode if compatible with engaged AFDS modes
    • Illuminates SPEED switch light
    • Annunciates MCP SPD autothrottle mode
    • Maintains speed in MCP IAS/MACH display.
  • Push – light illuminated
    • Deselects speed mode and extinguishes switch light
    • Engages A/T in ARM mode.

Speed Mode

  • Autothrottle holds speed in IAS/MACH display or a performance or limit speed. Speed mode engaged manually by pushing SPEED switch if speed mode is compatible with existing DFCS modes. Speed mode engages automatically when:
    • ALT ACQ engages
    • ALT HOLD engages
    • V/S engages
    • G/S capture occurs.
  • When the “N1 SET” outer knob is in the AUTO position the A/T will not set thrust above the displayed N1 limit, however, A/T can exceed an N1 value manually set with the “N1 SET” outer knob in the manual BOTH, 1, or 2 position. Setting the thrust reference manually is intended to provide guidance when manually controlling thrust.

7. IAS/MACH Selector

  • Rotate –
    • Sets speed in IAS/MACH display and positions airspeed cursor
    • Selected speed is reference speed for DFCS and A/T
    • Not operative when IAS/MACH display is blank.

8. Speed Intervention (SPD INTV) Switch

  • Push (when VNAV engaged) –
    • IAS/MACH display alternately shows selected IAS/Mach and blanks
    • When IAS/MACH display is unblanked, FMC speed intervention is active, FMC target speed is displayed, and IAS/MACH Selector may be used to set desired speed
    • When IAS/MACH display is blank, FMC computed target speed is active and displayed on the airspeed indicator.

9. VNAV Switch

  • Push –
    • VNAV switch light illuminates
    • Pitch mode annunciates VNAV SPD, VNAV PTH, or VNAV ALT
    • A/T mode annunciates FMC SPD, N1, RETARD, or ARM
    • IAS/MACH display blanks and airspeed cursors positioned to FMC commanded airspeed.

VNAV Mode

  • The FMC commands AFDS pitch and autothrottle to fly vertical profile selected on FMC CDUs. Profile includes climb, cruise, descent, speeds, and can also include waypoint altitude constraints.
  • VNAV arm criteria on the ground:
    • A valid flight plan has been entered.
    • Performance data has been entered and executed.
    • Both flight director switches have been switched on.
    • VNAV guidance becomes active at 400 feet AGL.
  • Climb –
    • Autothrottle holds FMC thrust limit
    • DFCS holds FMC target speed
    • Automatic level-off occurs at MCP altitude or VNAV altitude, whichever is reached first
    • MCP constrained altitude annunciates VNAV ALT
    • VNAV constrained altitude annunciates VNAV PTH.
  • Cruise –
    • Autothrottle holds FMC target speed
    • DFCS holds FMC altitude
    • Selecting a lower MCP altitude arms FMC to automatically begin descent upon arrival at FMC top of descent point.
  • Descent –
    • VNAV SPD descent
      • Autothrottle holds idle
      • DFCS holds FMC target speed.
    • VNAV PTH descent
      • Autothrottle holds idle but can command FMC SPD mode if ground speed becomes too low to maintain FMC vertical path
      • DFCS tracks FMC descent path.
    • Automatic level-off occurs at MCP altitude or VNAV altitude, whichever is reached first
      • MCP constrained altitude annunciates VNAV ALT
      • VNAV constrained altitude annunciates VNAV PTH.
  • Inhibited below 400 ft RA or if performance initialization not complete.

VNAV Mode Termination

  • VNAV mode is terminated by any one of the following:
    • Selecting another pitch mode
    • Glideslope capture
    • Reaching end of LNAV route
    • Transition of glideslope intercept waypoint if G/S is armed
    • Crosstrack deviation exceeds twice the RNP value during PTH descent for an active leg with a database vertical angle and LNAV not engaged.
  • In the event of glideslope intercept waypoint transition, VNAV can be re-engaged.

10. ALTITUDE Display

  • Displays selected altitude
    • Displayed altitude is reference for altitude alerting and automatic level–offs
    • Altitude range is 0 to 50,000 feet in 100 foot increments
    • Displays previously selected altitude when power first applied.

11. Vertical Speed (VERT SPEED) Display

  • Displays:
    • Blank when V/S mode not active
    • Present V/S when V/S mode is engaged with V/S switch
    • Selected V/S when V/S set with thumbwheel
    • Range is –7900 to +6000 fpm.
  • Display increments are:
    • 50 fpm if V/S is less than 1000 fpm
    • 100 fpm if V/S is 1000 fpm or greater.

12. Vertical Speed Thumbwheel

  • Rotate –
    • DN –
      • Sets vertical speed in VERT SPEED display
      • Increases rate of descent or reduces rate of ascent.
    • UP –
      • Sets vertical speed in VERT SPEED display
      • Increases rate of ascent or reduces rate of descent.

13. Level Change (LVL CHG) Switch

  • Push –
    • LVL CHG switch light illuminates
    • Pitch mode annunciates MCP SPD for climb or descent
    • Autothrottle mode annunciates N1 for climb and RETARD followed by ARM for descent
    • IAS/MACH display and airspeed cursors display target speed.

LVL CHG Mode

  • The LVL CHG mode coordinates pitch and thrust commands to make automatic climbs and descents to preselected altitudes at selected airspeeds.
  • A LVL CHG climb or descent is initiated by:
    • Selecting a new altitude
    • Pushing LVL CHG switch
    • Setting desired airspeed.
  • Climb –
    • Autothrottle holds limit thrust
    • DFCS holds selected airspeed.
  • Descent –
    • Autothrottle holds idle thrust
    • DFCS holds selected airspeed.
  • Airspeed –
    • If a speed mode is active when LVL CHG is engaged, this speed is retained as target speed
    • If a speed mode is not active when LVL CHG is engaged, existing speed becomes target speed
    • Speed can be changed with MCP IAS/MACH Selector.
  • The LVL CHG mode is inhibited after glideslope capture.

14. Altitude Selector (SEL)

  • Rotate –
    • Sets altitude in ALTITUDE display in 100 foot increments
    • Arms V/S mode if rotated while in ALT HOLD at selected altitude.

15. Altitude Hold (ALT HLD) Switch

  • Push –
    • Engages ALT HOLD command mode
    • Commands pitch to hold uncorrected barometric altitude at which switch was pressed
    • Annunciates ALT HOLD pitch mode and illuminates ALT HLD switch light.

Altitude Hold Command Mode

  • ALT HOLD mode commands pitch to hold either:
    • MCP selected altitude
      • Pitch mode annunciates ALT HOLD
      • ALT HLD switch light extinguishes.
    • Uncorrected barometric altitude at which ALT HLD switch was pressed if not at MCP selected altitude
      • Pitch mode annunciates ALT HOLD
      • ALT HLD switch light illuminates.
  • When in ALT HOLD at selected MCP altitude:
    • Selecting a new MCP altitude illuminates the ALT HLD switch light and arms V/S mode
    • LVL CHG, V/S, and VNAV climb and descent functions are inhibited until a new MCP altitude is selected.
  • ALT HOLD mode is inhibited after G/S capture.
  • The selected MCP altitude is referenced to:
    • Captain’s barometric altimeter setting for A A/P and F/D
    • First Officer’s barometric altimeter setting for B A/P and F/D.
  • Note: After ALT HOLD engages, changes in altimeter barometric settings do not change the selected altitude reference.

16. Vertical Speed (V/S) Switch

  • Push –
    • Arms or engages V/S command mode
    • Commands pitch to hold vertical speed
    • Engages A/T in speed mode to hold selected airspeed
    • Annunciates V/S pitch mode and illuminates V/S switch light.

Vertical Speed Command Mode

  • The V/S mode commands pitch to hold selected vertical speed and engages A/T in SPEED mode to hold selected airspeed. V/S mode has both an armed and an engaged state.
  • Engaged –
    • Annunciates V/S pitch mode
    • Vertical speed display changes from blank to present vertical speed
    • Desired vertical speeds can be selected with vertical speed thumbwheel.
  • V/S becomes armed if:
    • Pitch mode is ALT HLD at selected MCP altitude and
    • New MCP altitude is selected (more than 100 feet from current altitude).
  • With V/S armed, V/S mode is engaged by moving vertical speed thumbwheel.
  • V/S mode automatically engages if ALT ACQ mode is engaged and a new MCP altitude is selected which is more than 100 feet different from previously selected altitude.
    • Vertical speeds can be selected which command flight toward or away from selected altitude.
  • Inhibited if:
    • ALT HOLD mode is active at selected MCP altitude
    • Glideslope captured in APP mode.

17. Altitude Intervention (ALT INTV) Switch

Allows manual deletion of the next FMC altitude constraint via altitude SEL and ALT INTV switch.

  • Push – (during VNAV climb)
    • The lowest FMC altitude constraint below selected MCP altitude is deleted.
    • If the airplane is currently at an FMC altitude constraint, deletion allows the airplane to resume climb. MCP altitude must be set above current altitude.
    • For each press of the switch, one deletion occurs.
    • If MCP altitude is set above current FMC altitude, FMC cruise altitude resets to MCP altitude. FMC cruise altitude cannot be decreased using ALT INTV switch.
  • Push – (during VNAV cruise)
    • If MCP altitude is set above current FMC cruise altitude, FMC resets cruise altitude to MCP altitude and initiates a cruise climb.
    • If MCP altitude is set below current FMC cruise altitude, an early descent is initiated. Lower FMC cruise altitude cannot be entered using ALT INTV switch.
  • Push – (during VNAV descent)
    • The highest FMC altitude constraint above MCP altitude is deleted.
    • If the airplane is currently at an FMC altitude constraint, deletion allows the airplane to continue descent. MCP altitude must be set below current altitude.
    • If all FMC altitude constraints are deleted during VNAV path descent, an automatic transition to a VNAV speed descent is made.

18. COURSE Display

  • Displays course set by the course selector.
  • Note: Different courses and frequencies on two VHF NAV receivers can cause disagreement between Captain and FO F/D displays and affect A/P operation.

19. Heading Selector

  • Rotate –
    • Sets heading in HEADING display.
    • Positions selected heading bugs on the DUs.

20. HEADING Display

  • Displays selected heading.

21. LNAV Switch

  • Push –
    • Commands DFCS roll to intercept and track the active FMC route.
    • Annunciates LNAV as roll mode and illuminates LNAV switch light.

LNAV Mode

In LNAV mode, the FMC controls DFCS roll to intercept and track the active FMC route. The active route is entered and modified through FMC CDUs and can include SIDs, STARs, and instrument approaches.

  • LNAV arming criteria on the ground:
    • Origin runway in flight plan.
    • Active route entered in FMC.
    • Track of the first leg within 5 degrees of runway heading.
    • LNAV selected prior to TO/GA.
    • LNAV guidance becomes active at 50 feet AGL.
    • Bank angle is limited to 8 degrees below 200 feet and 30 degrees above 200 feet AGL.
  • LNAV engagement criteria in flight:
    • Active route entered in FMC.
    • Within 3 NM of active route, LNAV engagement occurs with any airplane heading.
    • Outside of 3 NM, the airplane must:
      • Be on intercept course of 90 degrees or less.
      • Intercept route segment before the active waypoint.
  • LNAV automatically disconnects for the following reasons:
    • Reaching the end of the active route.
    • Reaching a route discontinuity.
    • Intercepting a selected approach course in VOR LOC or APP modes (VOR/LOC armed).
    • Selecting HDG SEL.
    • Loss of capture criteria.

22. VOR Localizer (LOC) Switch

  • Push –
    • Commands DFCS roll to capture and track the selected VOR or LOC course.
    • Annunciates VOR/LOC armed or engaged as roll mode and illuminates VOR LOC switch light.

VOR LOC Mode

Pushing the VOR LOC switch selects VOR mode if a VOR frequency is tuned or selects LOC mode if a localizer frequency is tuned.

  • The VOR mode provides roll commands to track the selected VOR course.
  • The LOC mode provides roll commands to track the selected localizer course along the inbound front course bearing.
  • The selected course can be intercepted while engaged in:
    • LNAV.
    • HDG SEL.
    • CWS R if an autopilot is engaged in CMD.
  • The capture point is variable and depends on intercept angle and closure rate. Localizer capture occurs not later than 1/2 dot deviation. Course capture is indicated when VOR/LOC annunciation changes from armed to engaged.
  • While engaged in VOR or LOC modes:
    • A autopilot and Captain’s F/D use information from Captain’s course selector and No. 1 VHF NAV receiver.
    • B autopilot and First Officer’s F/D use information from First Officer’s course selector and No. 2 VHF NAV receiver.
    • Different courses and/or frequencies for two VHF NAV receivers can cause disagreement between the Captain’s and First Officer’s F/D displays and affect A/P operation.
  • Note: When a localizer frequency is selected, VHF NAV radios automatically switch from tail antenna to nose antenna when VOR/LOC is annunciated (armed or engaged). If antenna switching does not occur, LOC mode is inhibited.
  • Note: Localizer backcourse tracking is not available.

23. Course Selector

Sets course in COURSE display for related VHF NAV receiver, DFCS, and DU. Two course selectors and COURSE displays are located on the MCP.

  • Rotate Captain’s course selector – provides selected course information to:
    • A FCC.
    • No. 1 VHF NAV receiver.
    • Captain’s course pointer and course deviation bar.
    • Note: In VOR LOC or APP mode, the A A/P and Captain’s F/D use selected course and navigation data from the No. 1 VHF NAV receiver.
  • Rotate First Officer’s course selector – provides selected course information to:
    • B FCC.
    • No. 2 VHF NAV receiver.
    • First Officer’s course pointer and course deviation bar.
    • Note: In VOR LOC or APP mode, B A/P and First Officer’s F/D use selected course and navigation data from No. 2 VHF NAV receiver.

24. Bank Angle Selector

  • Rotate –
    • Sets maximum bank angle for DFCS operation in HDG SEL or VOR modes.
    • Commanded bank angle can be selected at 10, 15, 20, 25, or 30 degrees.

25. Heading Select (HDG SEL) Switch

  • Push –
    • Engages HDG SEL command mode.
    • Commands roll to follow the selected heading.
    • Annunciates HDG SEL as FMA roll mode and illuminates HDG SEL switch light.

Heading Select Command Mode

The HDG SEL mode commands roll to turn to and maintain the heading shown in MCP HEADING display:

  • Initial selection commands turn in the shortest direction toward selected heading bug.
  • After mode engagement, roll commands are given to turn in the same direction as rotation of the heading selector.
  • The bank angle limit is established by the bank angle selector.
  • HDG SEL mode automatically disengages upon capture of the selected radio course in VOR LOC and APP modes (VOR/LOC armed).

26. Approach (APP) Switch

  • Push –
    • Illuminates APP switch light.
    • Arms the DFCS for localizer and glideslope capture.
    • Roll mode annunciates VOR/LOC armed.
    • Pitch mode annunciates G/S armed.
    • Enables engagement of both autopilots.

APP Mode

The approach mode arms DFCS to capture and track localizer and glideslope and can be engaged for dual or single autopilot operation.

  • One VHF NAV receiver must be tuned to an ILS frequency before approach mode can be engaged. With one VHF NAV receiver tuned, onside DFCS is enabled for guidance and operation.
  • For dual autopilot operation, both VHF NAV receivers must be tuned to the ILS frequency and both autopilots must be selected in CMD prior to 800 feet RA.
  • APP mode operation:
    • The localizer must be captured prior to the glideslope.
    • The localizer can be intercepted in HDG SEL, LNAV, or CWS R.
    • SINGLE CH annunciates in A/P Status Display after localizer capture.
      • For single autopilot approach, SINGLE CH remains annunciated for the entire approach.
      • For dual autopilot approach, SINGLE CH annunciation extinguishes when the second autopilot engages and FLARE armed is annunciated.
    • Glideslope capture occurs at 2/5 dot below the glideslope.
    • The APP switch light extinguishes after localizer and glideslope capture.
  • After localizer and glideslope capture, APP mode can be disengaged by:
    • Pushing a TO/GA switch.
    • Disengaging autopilot(s) and turning off both F/D switches.
    • Retuning the VHF NAV receiver.
  • While engaged in the APP mode:
    • The A autopilot and Captain’s F/D use information from Captain’s Course Selector and No. 1 VHF NAV receiver.
    • The B autopilot and First Officer’s F/D use information from First Officer’s Course Selector and No. 2 VHF NAV receiver.
    • Different courses and/or frequencies for the two VHF NAV receivers can cause disagreement between Captain’s and First Officer’s F/D displays and affect A/P operation.

Note: After localizer or glideslope capture, during a single channel autopilot approach, CWS cannot be engaged by manually overriding pitch and/or roll control forces. Manually overriding pitch and/or roll will cause autopilot disengage. At autopilot disengage, the active Autopilot modes will remain engaged.

Note: During a dual autopilot approach and after FLARE ARM annunciation, any attempted manual override of the autopilots may result in an autopilot disengage.

Autopilot / Flight Director

Pushing a CMD or CWS switch engages related A/P in CMD or CWS and illuminates switch lights. A/P can operate in CMD, CWS, or a combination of CMD and CWS.

27. Command Engage (CMD ENGAGE) Switch (A or B)

  • Push –
    • Engages A/P.
    • Enables all command modes.
    • Displays CMD in A/P status display.
    • Pushing an engage switch for the second A/P, while not in approach mode, engages second A/P and disengages the first A/P.
    • Enables CWS operation.
    • CWS engages if:
      • Pitch or roll mode not selected.
      • Pitch or roll mode deselected.
      • Pitch or roll mode manually overridden with control column force.
    • CWS engaged displays:
      • CWS P and/or CWS R in A/P status display.
      • Blank in pitch and/or roll mode FMA.
    • When approaching a selected altitude in CWS P, the pitch mode engages in ALT ACQ and ALT HOLD when reaching selected altitude.
    • When approaching a selected radio course in CWS R with VOR/LOC or approach mode armed, VOR/LOC engages when course is intercepted.
    • If pitch is manually overridden while in ALT HOLD and control force is released within 250 feet of the selected altitude, A/P pitch mode engages in ALT ACQ and returns to selected altitude in ALT HOLD mode.
    • Note: During F/D only operation, while pitch or roll commands are more than 1/2 scale from center, pushing a CMD A or B switch engages the A/P in CWS for pitch and/or roll and the related F/D bar(s) retract.

28. Control Wheel Steering Engage (CWS ENGAGE) Switch (A or B)

  • Push –
    • Engages A/P.
    • Engages pitch and roll modes in CWS. Other pitch and roll modes not enabled.
    • Displays CWS P and CWS R in A/P status display.
    • CMD not displayed in A/P status display.
    • F/Ds, if ON, display guidance commands, and FD annunciates in A/P status display. A/P does not follow commands while in CWS.
    • A/P pitch and roll controlled by pilot with control wheel pressure.
    • When control pressure is released, A/P holds the existing attitude. If aileron pressure is released with 6 degrees or less bank, the A/P rolls wings level and holds the existing heading. Heading hold feature inhibited:
      • Below 1500 feet RA with gear down.
      • After LOC capture in APP mode.
      • After VOR capture with TAS 250 knots or less.

29. Autopilot Disengage (DISENGAGE) Bar

  • Pull down –
    • Exposes yellow background.
    • Disengages both A/Ps.
    • Prevents A/P engagement.
  • Lift up –
    • Conceals yellow background.
    • Enables A/P engagement.

30. Master (MA) Flight Director Indicators (white letters)

If an F/D switch is ON, the light indicates which FCC is controlling the F/D modes.

  • Illuminated – Related FCC is controlling F/D modes.
  • Extinguished – F/D modes are controlled from opposite FCC.
  • Both lights illuminated – Each FCC is controlling modes for related F/D.

31. Flight Director (F/D) Switch

  • Left F/D switch activates command bars on the Captain’s attitude indicator.
  • Right F/D switch activates command bars on the First Officer’s attitude indicator.
  • ON –
    • In flight with A/P ON and F/Ds OFF, turning an F/D switch ON engages F/D in currently selected A/P modes.
    • Displays FD in A/P status display if A/P is OFF or engaged in CWS.
    • Enables command bar display on the related pilot’s attitude indicator.
    • Command bars are displayed if command pitch and/or roll modes are engaged.
    • On the ground, arms pitch and roll modes for engagement in TO/GA and HDG SEL when the TO/GA switch is pushed.
  • OFF – Command bars retract from the related pilot’s attitude indicator.