CAT II/CATIIIa
Join Date: Jan 2007
Location: Vermont
Age: 67
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PurdueFlight, I have posted the relevant excerpt from the 737 NG FCTM. For more generic detail, probably more detail than you ever wanted, refer to AC 120-29A and AC 120-28D. In general, the equipment requirements will be specified by the operator's approved program, which will be driven by the aforementioned ACs for US operators. The requirements can vary widely between operators depending on when the program was approved and how it was constructed. In no case can the equipment requirements be less restrictive than what is specified by the AFM for that particular serial number aircraft.
Category II Operations
Category II approaches may be conducted using single or dual autopilots, or flight
director only, with two engines. For single autopilot operation, the autopilot must
be disengaged no lower than the minimum altitude listed in the Limitations
Chapter of the FCOM. The autothrottles should be disconnected when the
autopilot is disengaged.
Category II Approach Autopilot
The following equipment must be operative for an automatic approach requiring
the use of Category II minima:
• 1 (or more) autopilots engaged
• 2 independent sources of electrical power. (The APU may be a substitute
source of power for the left or right electrical system.)
• 2 ADIRU's associated with the engaged autopilot in NAV mode
• 2 attitude indicators including attitude, radio altitude, ILS deviation,
DA(H) indication and AFDS status
• both engines operating
• FMA for each pilot.
Category II Approach Flight Director
The following equipment must be operative for a Flight Director (FD) approach
requiring the use of Category II minima:
• 2 independent sources of electrical power. (The APU may be a substitute
source of power for the left or right electrical system.)
• 2 attitude indicators supplied by different display electronic units
including attitude, radio altitude, ILS deviation, DA(H) indication and
AFDS status
• 2 separate flight directors, selected
• 2 ADIRU's in NAV mode
• FMA for each pilot
• both engines operating.
Category III Operations
Category III operations are based on an approach to touchdown using the
automatic landing system. Normal operations should not require pilot
intervention. However, pilot intervention should be anticipated in the event
inadequate airplane performance is suspected, or when an automatic landing
cannot be safely accomplished in the touchdown zone. Guard the controls on
approach through landing and be prepared to take over manually, if required.
Note: For fail operational airplanes (airplanes with autopilot rollout guidance),
the controls should be guarded through the landing roll.
The fail operational airplane is certified for Category IIIb operations with two
engines operating for flaps 30 or 40 landing, or, when certified, with one engine
operating for flaps 30 landing.
Category IIIa/Autoland
For Category IIIa operations the following equipment must be operative and
FLARE arm (LAND 3 or LAND 2 for fail operational airplanes) annunciated:
• 2 independent sources of electrical power. (The APU generator may be a
substitute source of power for the left or right electrical system.)
• 2 autopilots engaged
• 2 attitude indicators supplied by different display electronic units
including attitude, radio altitude, ILS deviation, DA(H), and AFDS status
• 2 ADIRU's in NAV mode
• both engines operating (fail passive airplanes)
• one or two engines operating (fail operational airplanes)
• 2 hydraulic systems
• FMA for each pilot.
Category IIIb/Autoland
For Category IIIb operations, visual reference is not normally a specific
requirement for continuation of the approach to touchdown.
For Category IIIb operations the following equipment must be operative and
LAND 3 annunciated:
• one or two engines operating (use Cat IIIa weather minimums for one
engine)
• FMA for each pilot
• autothrottle at the start of final approach
• approach minima display for each pilot
• autoland status annunciation on both pilots’ displays
• antiskid operational
• normal flight controls
• windshield wipers for each pilot.
Category II Operations
Category II approaches may be conducted using single or dual autopilots, or flight
director only, with two engines. For single autopilot operation, the autopilot must
be disengaged no lower than the minimum altitude listed in the Limitations
Chapter of the FCOM. The autothrottles should be disconnected when the
autopilot is disengaged.
Category II Approach Autopilot
The following equipment must be operative for an automatic approach requiring
the use of Category II minima:
• 1 (or more) autopilots engaged
• 2 independent sources of electrical power. (The APU may be a substitute
source of power for the left or right electrical system.)
• 2 ADIRU's associated with the engaged autopilot in NAV mode
• 2 attitude indicators including attitude, radio altitude, ILS deviation,
DA(H) indication and AFDS status
• both engines operating
• FMA for each pilot.
Category II Approach Flight Director
The following equipment must be operative for a Flight Director (FD) approach
requiring the use of Category II minima:
• 2 independent sources of electrical power. (The APU may be a substitute
source of power for the left or right electrical system.)
• 2 attitude indicators supplied by different display electronic units
including attitude, radio altitude, ILS deviation, DA(H) indication and
AFDS status
• 2 separate flight directors, selected
• 2 ADIRU's in NAV mode
• FMA for each pilot
• both engines operating.
Category III Operations
Category III operations are based on an approach to touchdown using the
automatic landing system. Normal operations should not require pilot
intervention. However, pilot intervention should be anticipated in the event
inadequate airplane performance is suspected, or when an automatic landing
cannot be safely accomplished in the touchdown zone. Guard the controls on
approach through landing and be prepared to take over manually, if required.
Note: For fail operational airplanes (airplanes with autopilot rollout guidance),
the controls should be guarded through the landing roll.
The fail operational airplane is certified for Category IIIb operations with two
engines operating for flaps 30 or 40 landing, or, when certified, with one engine
operating for flaps 30 landing.
Category IIIa/Autoland
For Category IIIa operations the following equipment must be operative and
FLARE arm (LAND 3 or LAND 2 for fail operational airplanes) annunciated:
• 2 independent sources of electrical power. (The APU generator may be a
substitute source of power for the left or right electrical system.)
• 2 autopilots engaged
• 2 attitude indicators supplied by different display electronic units
including attitude, radio altitude, ILS deviation, DA(H), and AFDS status
• 2 ADIRU's in NAV mode
• both engines operating (fail passive airplanes)
• one or two engines operating (fail operational airplanes)
• 2 hydraulic systems
• FMA for each pilot.
Category IIIb/Autoland
For Category IIIb operations, visual reference is not normally a specific
requirement for continuation of the approach to touchdown.
For Category IIIb operations the following equipment must be operative and
LAND 3 annunciated:
• one or two engines operating (use Cat IIIa weather minimums for one
engine)
• FMA for each pilot
• autothrottle at the start of final approach
• approach minima display for each pilot
• autoland status annunciation on both pilots’ displays
• antiskid operational
• normal flight controls
• windshield wipers for each pilot.
