737 MAX Automatic Flight Questions

Why might an autopilot use more than one independent computation channel when flying an automatic landing?

• So the channels can cross-monitor each other, reducing the chance that a single computation fault leads to an unsafe automatic landing
• Extra channels are used only to make the autopilot fly faster approaches
• A second channel exists purely as an unused spare with no active function
• Multiple channels are required only for manual (non-automatic) landings

Explanation: For the demanding, low-margin task of an automatic landing, using multiple independent autopilot channels that continuously cross-check each other's outputs adds redundancy and fault detection that a single channel can't provide - if the channels disagree beyond an acceptable tolerance, the system can disconnect or revert rather than risk an unsafe automatic landing.

Automatic Flight - Multi-Channel Autopilot

What is a common function of an autothrottle system during the landing flare?

• It automatically retards the thrust levers toward idle at a defined height above the runway, rather than requiring the pilot to manually close them
• It automatically advances to maximum thrust just before touchdown
• It disengages completely the moment the aircraft descends below 1,000 feet
• It has no function at all during the landing phase

Explanation: Many autothrottle systems are designed to automatically retard the thrust levers toward idle once the aircraft descends through a defined height during the flare, reducing pilot workload at a busy phase of flight - though the pilot can also manually retard the throttles if needed.

Automatic Flight - Autothrottle Retard Function

What is the general function of a mode control panel (MCP) in the automatic flight system?

• It's the panel where the crew selects autopilot/flight director/autothrottle modes and enters targets such as altitude, heading, and speed
• It is used only to control cabin lighting
• It exists solely to display outside air temperature
• It is a purely passive display with no selectable controls at all

Explanation: The mode control panel is the crew's primary interface for commanding the automatic flight system - selecting which lateral and vertical modes the flight director/autopilot/autothrottle should fly in, and dialing in numeric targets like a selected altitude, heading, or airspeed for those modes to fly toward.

Automatic Flight - Mode Control Panel

What is the general purpose of the flight director's command bars (or steering cues) on the primary flight display?

• They show the pitch and roll guidance needed to fly the currently selected mode's targets, whether the pilot is following them manually or the autopilot is flying them automatically
• They display only the current outside air temperature
• They exist purely to show cabin pressure differential
• They are visible only when the autopilot is engaged, never during manual flight director use

Explanation: The command bars translate whatever the automatic flight system's currently selected modes are commanding - a heading, an altitude, a glidepath, and so on - into a simple pitch-and-roll steering cue on the primary flight display, which the pilot can hand-fly by following, or which the autopilot itself uses as its own guidance if engaged.

Automatic Flight - Flight Director Command Bars

What is the general function of a heading (or track) select mode on the automatic flight system?

• The crew dials in a desired heading or track, and the autopilot turns the aircraft to intercept and then hold it
• It can only maintain whatever heading the aircraft happened to be on at engagement, with no ability to select a new one
• It controls altitude rather than lateral direction
• It is used only during an automatic landing, never in cruise

Explanation: A heading/track select mode is a straightforward way for the crew to command a lateral change: dialing in the desired value and engaging the mode causes the autopilot to turn the aircraft (typically in the selected direction) to intercept and then maintain that heading or track, without needing to fly it manually.

Automatic Flight - Heading/Track Select Mode

In a typical automatic approach mode sequence, what is the general order of localizer and glideslope engagement?

• The localizer mode is generally armed and captured first, establishing lateral alignment with the runway centerline, with the glideslope mode then arming and capturing to establish the vertical approach path
• The glideslope is always captured before the localizer, with lateral alignment established last
• Both must be manually flown by the pilot with no automatic capture available at all
• There is no defined sequence; either can be captured in any order with no operational difference

Explanation: The typical sequence arms the localizer first so the aircraft captures and establishes lateral alignment with the runway centerline, with the glideslope mode then arming and subsequently capturing the vertical path once the aircraft is established - a sequence that reflects getting the aircraft correctly lined up with the runway before beginning to follow the vertical descent profile.

Automatic Flight - Localizer/Glideslope Capture Sequence

What is the general purpose of a flight mode annunciator (FMA) on the primary flight display?

• It shows the crew exactly which autopilot, flight director, and autothrottle modes are currently active or armed, so there's no ambiguity about what the automation is doing
• It displays only the current outside air temperature
• It shows fuel quantity rather than automation mode status
• It is visible only when all automation is switched off

Explanation: The flight mode annunciator is specifically there to remove any guesswork about what the automatic flight system is currently doing - clearly displaying the active and armed lateral, vertical, and autothrottle modes so the crew can confirm the aircraft is actually configured the way they intend, rather than having to infer it from aircraft behavior alone.

Automatic Flight - Flight Mode Annunciator

Why is fully automatic landing (autoland) generally only approved for use on certain types of instrument approaches, rather than being available on any approach?

• Autoland relies on a sufficiently precise and reliable vertical and lateral guidance signal (such as an instrument landing system) to safely fly the aircraft all the way to touchdown, which not every approach type provides
• Autoland can be used on literally any approach type with no restriction whatsoever
• Autoland is restricted only by weather, never by the type of approach being flown
• Autoland requires no external guidance signal at all

Explanation: Flying the aircraft automatically all the way to touchdown demands a guidance signal precise and reliable enough to safely support that - something an instrument landing system approach is specifically built to provide, but many other approach types are not - which is why autoland approval is generally tied to specific approach types rather than being available universally.

Automatic Flight - Autoland Approach Type Restriction