.
Monitor ILS raw data throughout the approach.
Distortion of Localizer/Glideslope Beam
If distortion or oscillation of the localizer/glideslope beam occurs, the autopilot will attempt to follow the signal resulting in undesirable aircraft response. Erratic ILS signals are easily detected by noting the raw data displays.
Note: There are restrictions on ground and air movements near Cat II/III runways during Cat II weather conditions. When weather conditions are Cat I or better the restrictions do not apply and localizer/glideslope beam distortions are more likely.
Decision Regime Performance Limits
The decision regime will be from 500 feet above the TDZE to the flare. Performance limits in the decision regime are:
.
Airspeed: ±5 knots of target speed.
.
Glideslope: Significant deviation not to exceed ±1 dot.
.
Localizer: Cat I: 1 dot right or left of centered CDI Cat II: 1/3 dot right or left of centered CDI.
.
Illumination or any warning/caution lights or flags not previously deemed acceptable: none allowed.
Note: To avoid distractions or potential confusion when the aircraft is below 500 feet above TDZE, any initial/new warning light or flag that comes into view in the decision regime requires a missed approach even if that warning light or flag would be acceptable under the required equipment list for the type of approach being flown. A warning light or flag that has been identified prior to the decision regime, and does not disqualify the aircraft from the approach being flown, is acceptable in the decision regime.
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Raw Data must match up with computed data.
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Rate of Descent: Maximum of 1,000 feet per minute.
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Maximum stabilized crab angle: 10°.
.
GPWS activation: none allowed.
Any violation of these performance limits in the decision regime mandates an immediate go-around. Prior to the Captain taking control of the aircraft, the Captain will command and the First Officer will execute the go-around. After the Captain has taken control of the aircraft, the First Officer will advise of any deviations beyond the performance limits and the Captain will execute the go-around.
The Importance of Visual Cues
Caution: During low visibility or night approaches, the touchdown point
may not be visible to the pilot at DA(H). Be aware of the
tendency to “DUCK UNDER” the glideslope when manually
controlling the aircraft during these conditions.
The autopilot should be used to the minimum authorized altitude to prevent “Duck Under.” For Cat II operations, the importance of visual cues prior to and during descent below DA(H) cannot be overemphasized. A flaps 40° approach is recommended to improve the forward visual sight picture by the reduced deck angle. DA(H) is defined as a specified height above the elevation of the touchdown zone at which a decision must be made to continue the approach or to initiate a missed approach.
At DA(H) the flight crew must be satisfied that the total pattern of visual cues provides sufficient guidance to continue the approach and landing. If the aircraft is not tracking so as to remain within the lateral confines of the runway and land within the touchdown zone, the flight crew must accomplish a missed approach. If the approach is continued, it is imperative that the required visual references be continuously maintained. Flight crews should realize that visual cues can be lost after DA(H) by encountering shallow fog, snow flurries, or heavy precipitation. Whenever visual cues are lost after DA(H), the flight crew should immediately accomplish a missed approach.
Use of the landing lights is at the option of the Captain. Under certain atmospheric conditions, the use of landing lights will reduce visibility at DA(H). Flight crews may find it advantageous to delay the use of landing lights until after touchdown.
Crew Actions / Callouts
ILS Mode Monitored Approach
Condition / Location ACTION / CALLOUT
Captain First Officer
1,000’ above TDZE “1,000”
500’ above TDZE “500”
400’ above TDZE “400”
300’ above TDZE (Cat II only) “300”
100’ above DA(H) “Approaching minimums, I’m going heads up” Is prepared to accomplish missed approach at DA(H)
At DA(H) (Cat I - Baro Altimeter) (Cat II – Radar Altimeter or inner marker) If Captain has not taken control of the aircraft. Monitor F/O missed approach. “Minimums, going around” Accomplish missed approach.
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