Autoflight 737 Flashcards
Disengage AP, what criteria?
* pushing either A/P disengage switch
* push TO/GA sw with single A/P engaged in CWS/CMD below 2,000ft RA
* pushing TO/GA sw with a single A/P engaged in CWS/CMD at or above 2,000ft RA with flaps not up or G/S engaged
* pushing TO/GA switch after touchdown with both A/Ps engaged in CMD
* pushing an illuminated A/P ENGAGE switch
* pushing the A/P DISENGAGE bar down
* activating either pilot’s control wheel trim switch
* moving the STAB TRIM AUTOPILOT cutout switch to CUTOUT
* either left or right IRS system failure or FAULT light illuminated
* loss of electrical power or a sensor input which prevents proper operation of the engaged A/P and mode
* loss of respective hydraulic system pressure.
VH-VXP - VH-XZP
* pitch or roll mode manually overriden with control column or wheel force.
Note: Loss of the system A engine-driven hydraulic pump, and a heavy demand on system A, may cause A/P A to disengage
How many Gens required for dual channel AP operation?
2
What happens with a RadAlt failure regarding AP?
Two independent radio altimeters provide radio altitude to the respective FCCs. With a radio altimeter inoperative, the autopilot will disengage two seconds after LOC and GS capture. Fcom
Does the FD give landing flare guidance?
the F/D has no landing flare capability. F/D command bars retract from view at approximately 50ft RA on an ILS approach
How is VNAV mode terminated?
* 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.
What is the precaution required when going into ALT ACQ on a VNAV SPD descent?
When the pitch mode changes from VNAV SPD to ALT ACQ during an intermediate level off, the autothrottle will command a target IAS rather than Mach number. This is valid even at altitudes above the IAS/Mach changeover. If the climb is resumed in LVL CHG or V/S, the airspeed window opens at the target IAS which may result in an overspeed condition.
Explain VNAV in climb:
What does AT control and what does AFDS control?
* autothrottle holds FMC thrust limit
* AFDS holds FMC target speed
* automatic level-off occurs at MCP altitude or VNAV altitude, whichever is reached first
* VNAV constrained altitude annunciates VNAV PTH.
Explain VNAV in CRZ
What does AT control and what does AFDS control?
* autothrottle holds FMC target speed
* AFDS holds FMC altitude
* selecting a lower MCP altitude arms FMC to automatically begin descent upon arrival at FMC top of descent point
Explain VNAV in Descent
What does AT control and what does AFDS control?
VNAV SPD vs VNAV PTH
- VNAV SPD descent*
* autothrottle holds idle
* AFDS 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
AFDS tracks FMC descent path.
automatic level-off occurs at MCP altitude or VNAV altitude, whichever is reached first
* VNAV constrained altitude annunciates VNAV PTH.
Altitude intervention VNAV Climb
Push – (during VNAV climb)
* lowest FMC altitude constraint below selected MCP altitude is deleted
* if airplane is currently at an FMC altitude constraint, deletion allows airplane to resume climb. MCP altitude must be set above current altitude
* for each press of 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.
Altitude intervention VNAV cruise
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 an MCP ALT is set to a lower altitude, but at or above any descent constraint, a CRZ DES occurs if the airplane is further than 50nm from the top of descent at the current cruise altitude. The result will be a cruise altitude reset to the MCP ALT and vertical speed commands of -1,000fpm to the new cruise altitude. If within 50nm of the top of descent, the Early Descent mode will be invoked
* if more than 50nm to T/D with VNAV engaged and the MCP ALT below current altitude and below a descent constraint altitude, the result will be Early Descent vertical speed commands of -1,000fpm until path intercept or MCP ALT level off occurs.
Altitude intervention VNAV descent
* the highest FMC altitude constraint above MCP altitude is deleted
* if airplane is currently at an FMC altitude constraint, deletion allows 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
When is auto changeover IAS/mach?
FL260
What are the overspeed and underspeed symbols on MCP?
Appear when command speed can’t be reached.
Underspeed flashing A
Overspeed flashing 8
Explain the N1 MCP switch and associated mode.
NI
Push – (light not illuminated)
* engages A/T in N1 mode if compatible with AFDS 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 AFDS 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
Explain SPD MCP switch and associated modes.
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 AFDS 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
How will the AT respond to TOGA push on approach?
Single press.
With the A/T Arm switch at ARM, the A/T go–around mode is armed:* when descending below 2,000ft RA (below 15,500ft pressure altitude if both RAs have failed)
* with or without the AFDS engaged.
Note: With the A/T switch at ARM, when at or above 2,000ft RA (at or above 15,500ft pressure altitude if both RAs have failed), with flaps not up or G/S captured, the A/T will respond to a TO/GA switch push, but will engage in the A/T N1 thrust mode and not the reduced go around thrust mode.
Autothrottle ARM mode
The autothrottle ARM mode is normally not recommended because its function can be confusing.
The primary feature the autothrottle ARM mode provides is minimum speed protection in the event the airplane slows to minimum manoeuvre speed.
Other features normally associated with the autothrottle, such as gust protection, are not provided. The autothrottle ARM mode should not be used with Non-Normal Checklists. Some malfunctions that affect manoeuvre speeds cause the autothrottle to maintain a speed above approach speed
