3. INTRODUCTION
CAT II / CAT III provides a level of
safety when landing in low visibility
conditions, equivalent to that of
'normal' operating conditions
Category II / Category III constitutes
the main part of All Weather
Operations (AWO), which also consists
of Category I, take-off, and taxiing in
low visibility conditions
Moreover, approach success rate in
actual in-line services is now nearly
100%
4. INTRODUCTION
Although ICAO, the FAA and EASA regulations are
slightly different, all refer to the same concepts for CAT
II/CAT III operations
CATII provides sufficient visual reference to permit a
manual landing at DH
CATIII does not provide sufficient visual references and
requires an automatic landing system
5. INTRODUCTION
In Category III, pilots see the runway lights only few seconds (about
5 seconds) before touchdown
6. MAIN OBJECTIVES
To maintain required level of safety AWO concept must
fulfill:
the aircraft
the airfield
the flight crew
the operator
7. DECISION HEIGHT VS RVR
All definitions refer to the concept of Decision Height
(DH) and Runway Visual Range (RVR)
It is worth noting the difference between Cat II definitions
by ICAO and FAA, and the definition by EASA of the
minimum runway visual range
8. DECISION HEIGHT
Is the wheel height above the runway elevation by which
a go-around must be initiated unless adequate visual
reference has been established or
The aircraft position and approach path have been
assessed as satisfactory to continue the approach and
landing in safety (EASA)
9. DECISION HEIGHT
In Category II operations, DH is always limited to 100ft or Obstacle
Clearance Height (OCH) whichever is higher
In Category III operations with DH, the DH is lower than 100ft
When necessary, the published DH takes into account the terrain
profile before runway threshold
10. ALERT HEIGHT
Is a height above the runway, based on the
characteristics of the aeroplane and its fail-operational
automatic landing system, above which a Category III
approach would be discontinued and a missed approach
initiated if a failure occurred in one of the redundant parts
of the automatic landing system, or in the relevant ground
equipment (ICAO)
Alert Height is connected with LAND2, LAND3 or NO
AUTOLAND annunciation
11. ALERT HEIGHT
Fail-operational automatic landing system - if in
the event of a failure, the approach, flare and landing
can be completed by the remaining part of the
automatic system
Fail-passive automatic landing system - in the
event of a failure there is no significant deviation of
aeroplane trim, flight path or altitude but the landing
will not be completed automatically
12.
13. ALERT HEIGHT
Go-around above Alert Height for failures affecting
fail operational system
Below Alert Height continue except for Autoland
warning
Height evaluated during certification - typically 100 -
200feet (200 - B737)
Operators can select lower Alert Height
14. RUNWAY VISUAL RANGE
Range over which a pilot of an aircraft on the centreline
of the runway can see the runway surface markings or
the lights delineating the runway or identifying its
centreline
Transmissometers strategically located
Three basic portions of runway - the touchdown zone
(TDZ), the mid-runway portion (MID) and stop end
15. RUNWAY VISUAL RANGE
RVR reports
Reports are given with 50 m increments if RVR is less
than 800 m
25 m increments if RVR drops below 150 m
No need to give MID and END value by ATC if they are
higher or equal than TDZ
ATC must have an update of RVR every 15s available
17. RUNWAY VISUAL RANGE
Minimum visual segments at DH have been
established for each category
Typical values are 200m for CAT IIIA and 300m for
CAT II automatic landing
18. RUNWAY VISUAL RANGE
A too-low seat adjustment may greatly reduce the visual
segment
When the eye reference position is lower than intended,
the already short visual segment is further reduced by the
cut-off angle of the glareshield or nose
21. RVR MINIMA
Pilots require 1-3 seconds to establish visual contact
To establish lateral position pilots required to see not less than three
lights
Establish an RVR to to be associated with that DH to ensure required
visual reference is established
Eye position is important
22. MINIMUM APPROACH BREAK-OFF
HEIGHT
Is the lowest height above ground measured by radio-
altimeter such that if a missed approach is initiated
without external references
Replaced by minimum DH or indication in AFM of altitude
loss during automatic go around - either MABH or altitude
loss in AFM can be use to determine minimum DH in CAT
III operation
23. MINIMUM APPROACH BREAK-OFF
HEIGHT
REFERENCE LOST below DH = immediate go around
a) by pressing TO/GA above 20 ft aircraft stays airborne
b) by pressing TO/GA below 20 ft aircraft will make go
around contact by main landing gear – TO/GA feature
available
c) by pressing TO/GA below 20 ft aircraft will make
ground contact by all wheels – TO/GA feature inhibited,
roll out must be completed
24. OPERATING MINIMA
Minima are generally expressed
by RVR and DH
There is direct corellation
between both of them
DH vs RVR can be influenced
either by:
a) approach lighting system
capability
b) or close in obstacles
26. OPERATING MINIMA
An operator is responsible to establish its minima which
cannot be lower than:
Airfield operating minima - OCA (H)
System minimum
Minimum stated by state authority
Aircraft minima stated in AFM
Crew minima
AXE uses minima provided by LIDO up to CAT II but own
minima for CAT IIIA to fulfill missed approach gradient
29. GENERAL CONCEPT
CAT II
CAT II weather minima has been established to provide
sufficient visual references at DH to permit a manual
landing (or a missed approach) to be executed (it does
not mean that the landing must be made manually).
More restrictive RVR can be imposed by the procedure in
case of CATII manual landing
30. GENERAL CONCEPT
CAT II
ICAO definition
DH lower than 200ft but not less than100ft
RVR not less than 350m
EASA definition
DH lower than 200ft but not lower than 100ft
RVR not less than 300m
31. GENERAL CONCEPT
CAT II
As it is sometimes necessary to increase DH (close in
obstacles), the RVR minima according to EASA and FAA
are a function of the DH
B737 DH RVR
CAT II
100-120 300
121-140 400
141-199 450
32. GENERAL CONCEPT
CAT II
TDZ MID END
APP CHART 125m 75m
As per AXE other measured parts of RWY must fulfill following RVR minima:
END RVR required if speed at this part is more than 60 kts
33. GENERAL CONCEPT
CAT III
A CAT III operation is a precision approach at lower than
CAT II minima
CAT III weather minima do not provide sufficient visual
references to allow a manual landing
Pilot decides if the aircraft will land in the touchdown
zone (basically CAT III A) and to ensure safety during
rollout (basically CAT III B)
Automatic landing system is mandatory to perform
Category III operations
35. GENERAL CONCEPT
CAT III
Automatic landing is not CAT III and is not related to
particular weather conditions
This system is mandatory for all CAT III operations
Perform automatic landing in good visibility but ILS
performance must be sufficient and ILS signals protected
37. GENERAL CONCEPT
CAT IIIA
ICAO and FAA definition
No decision height or a decision height lower than 100ft
and a runway visual range not less than 200m
EASA definition
DH lower than 100ft and a runway visual range not less
than 200m
38. GENERAL CONCEPT
CAT IIIA
TDZ MID END
APP CHART 125m 75m
As per AXE other measured parts of RWY must fulfill following RVR minima:
END RVR required if speed at this part is more than 60 kts
39. GENERAL CONCEPT
CAT IIIB
ICAO and FAA definition
No decision height or a decision height lower than 50ft
and a runway visual range less than 200m but not less
than 50m
EASA definition
No decision height or a decision height lower than 50ft
and a runway visual range less than 200m but not less
than 75m
40. GENERAL CONCEPT
CAT IIIC
ICAO and FAA definition
No decision height and no runway visual range limitation
CAT III C operations are not currently authorized and the
EASA does not mention this sub-category
43. AUTOMATIC LANDING CAT II/IIIA
Mandatory equipment:
Dual channel A/P
Low range radio altimeter and display
DH light or display
Two ADIRU (IRU in NAV mode)
Windshield rain removal system
FMA for each pilot
ILS receiver and display for both pilots
Two sources of electrical power
44. LOW VISIBILITY TAKE OFF
Takeoff with RVR less than 400m is considered as LVTO
by EU OPS
The Takeoff minima is mainly determined by the airport
installation (runway lighting system, RVR measurement
system, ...)
45. LOW VISIBILITY TAKE OFF
Facilities RVR
Night: w/o HIRL 700
Day: w/o HIRL 500
Day: runway edge lights and
runway centre line markings
Night: runway edge lights and
runway end lights or runway centre
line lights and runway end lights
300
Runway edge lights and runway
centre line lights 200
Runway edge lights and runway
centre line lights + multiple RVR
information
150
High intensity runway centre line
lights spaced 15m or lessand high
intensity edge lights spaced 60m or
less + multiple RVR information
125
46. LOW VISIBILITY TAKE OFF
Take-off minima 125m RVR:
LVO in force at the airport
HIRL spaced 15m + high intensity edge lights spaced
60m or less
Crew training undergone
90m visual segment clearly visisble
The required RVR has been achieved for all relevant
RVR reporting points
47. LOW VISIBILITY TAKE OFF
Wind component Wind velocity
Headwind 35
Crosswind 20
Tailwind 10
B737NG AFM wind limitation:
48. LOW VISIBILITY TAKE OFF
Additional considerations
Takeoff alternate is normally required within one hour for
twins
Conditions - one engine inoperative speed in still air in
ISA conditions based on actual take-off speed
Max. distance for B737-800 is 255NM
Allowance for fail operational systems
49. LOW VISIBILITY TAKE OFF
INSTRUMENT SETTING
MCP course display (both) Runway heading of the active rwy
NAV1 ILS of the active RWY
NAV2 ILS of the active RWY
EHSI 1 EFIS mode in map mode
EHSI 2 EFIS mode in RAW DATA or
expanded RAW data
Instrument setting as per AXE SOPs:
50. FLIGHT CREW PROCEDURES
If CATII/III approach has been conducted CAT II/IIIA
report must be filled
All airports intended to be used for CAT IIIA approach
must be before verified by the approach to CAT IIIA
performed in conditions equal or better than CAT II
minima (EU-OPS, CAT)
Status of an airports can be found and verified in List of
Adequate Airports in LIDO AXE manuals
52. FLIGHT CREW PROCEDURES
The pilot at the left pilot seat (PIC) is always the pilot
flying (PF)
The pilot at the right pilot seat (FO) is always pilot
monitoring (PM)
Take-off briefing is performed prior taxing
53. FLIGHT CREW PROCEDURES
The PIC shall be PF if RVR or VIS drops below 800m
Take-off is performed after stopping on the RWY
Landing flaps extended to 40°
Min. autobrake setting should be 3
54. FLIGHT PROCEDURES
IN FLIGHT TASK SHARING:
PF monitors the flight instruments and at 100ft above the
DH shifts his view otside to establish visual contact
PM monitors the flight instruments and announce any
deviation
PM monitors flight instruments through all flight down to
DH, landing until reaching taxi speed
In addition performs following call-outs
55. FLIGHT PROCEDURES
CAT II
At DH = 100ft
GPWS voice MINIMUM
PF LANDING or GO AROUND
At 50ft
PM FLARE or NO FLARE
At 27ft
PM RETARD or NO RETARD
56. FLIGHT PROCEDURES
CAT IIIA
At DH = 50ft
GPWS voice MINIMUM
PM FLARE or NO FLARE
PF LANDING or GO AROUND
At 27ft
PM RETARD or NO RETARD
57. FLIGHT PROCEDURES
MCP course selector APP inbound course
NAV CPT ILS of RWY in use
NAV FO ILS of RWY in use
ND or EHSI CPT MAP mode
ND or EHSI FO APP mode
ADF 1 LOM
ADF 2 LMM or NDB behind the RWY
58. FLIGHT PROCEDURES
Required visual reference:
Approach lights (3 in sequence)
Runway centre line lights (3 in sequence)
TDZ lights
RWY edge lights
Or combination of all the above
CAT II approach - lateral element of approach aids
59. FLIGHT PROCEDURES
Go around – manual or automatic
Automatic go around – 3 reasons:
1. instructed by ATC
2. no visual contact or contact lost below DH
3. PF incapacitation
60. AUTOPILOT FAILURES
Steady red A/P disengage warning light
1. Below 800 ft during approach – stab out of trim –
disengage A/P manual go around
2. During G/A – elevator position not suitable for single
channel operation – manual level-off or set higher MCP
altitude
61. AUTOPILOT FAILURES
No FLARE annunciation – 500 ft RA during approach –
pitch and roll monitors may not be enabled or only first
A/P channel is engaged – disengage A/P manual go
around
62. AUTOPILOT FAILURES
Flashing red A/T disengage light – A/T is disengaged –
continue approach retard thrust manually
Flashing red AUTOLAND light – below 500 ft – A/P
disengages or stab trim warning occurs – disengage A/P
manual go around
Flashing red AUTOLAND light – below 200 ft – ILS
deviation warning occurs – disengage A/P manual go
around
63. AIRFIELD REQUIREMENTS
The following subjects:
runway characteristics
visual aids
non-Visual aids (ILS)
RVR measurements
obstacle clearance area
ATC procedure,
maintenance procedure
64. RUNWAY CHARACTERISTICS
RUNWAY LENGTH
There is no specific
requirement
Only an operational limitation
RUNWAY WIDTH
Not less than 45m
Touchdownzone beginning at
the threshold and extending to
a distance of 900m
65. RUNWAY CHARACTERISTICS
RUNWAY SLOPE
First and the last quarter of the length of the runway the
slope does not exceed 0.8%
Slope maximum of 2% per 30m
66. RUNWAY CHARACTERISTICS
OBJECTS ON RUNWAY
STRIPS
No fixed object (other than
frangible visual aids) are
installed on a runway strip
within 60m of the
centerline
The distance between the
holding position and the
centerline of the runway is
not less than 90m
67. VISUAL AIDS
Runway centerline marks must have a width not less
than 0.90 m
CAT II or CAT III signs placed on either edge of the
taxiway at the holding-position
Sign CAT III must be accompanied with flashing lights.
68. VISUAL AIDS
Runway lights for CAT II or
CAT III consist of:
high intensity threshold lights
runway end lights
runway touchdown zone lights
runway edge lights
runway centerline lights
69. VISUAL AIDS-APPROACH LIGHT SYSTEM
The ALS is mandatory for CAT II operations
Optional for CAT III operations
Row of lights on the extended centreline of the runway,
extending over a distance of 300m from the threshold
(over 900m for CAT I)
System has two side rows of lights, extending 270m from
the threshold, and two crossbars, one at 150m and one
at 300m from the threshold
70. ILS FACILITY
In CAT II and III approaches, the ILS beams must be
protected from unacceptable disturbance
Two kinds of protection area are defined
the critical area
the sensitive area