Continuous Descent Final Approach (CDFA)

THE PAST-DIVE AND DRIVE APPROACHES:

1. Normally a 1000 fpm or more rate of descent is established.

2. DISADVANTAGE: Pilots have to calculate the VDP (Visual Descent Point) by determining the height above the airport

(HAA) of the MDA(H) and use 300ft per NM distance to the runway.

Unstable Final Approach. Terrain Closure Rate. Runway Alignment. Aircraft Configuration Changes.

3. ( CFIT ) CONTROLLED FLIGHT INTO TERRAIN APPROACH ACCIDENTS:

Most Common Causes: Un-stabilized Approaches. Descent below MDA.

4. RECOMENDATIONS: Establishing and adhering to SOPs. Operators should define parameters for a stabilized approach. Implement Constant-Angle and Rate-of-Descent procedures. Train flight crews in proper use of Constant-Angle procedures.

THE PRESENT-V/S (CONSTANT ANGLE):

1. INSTRUMENT APPROACH USING VERTICAL SPEED.

Set desired V/S to descend to MDA(H). Use a V/S that results no level flight segment at MDA(H). Using 300 feet per mile for a 3° path(3 NM 2NM etc ) example: 900 feet - 3NM, 600 feet -2NM,

etc.

THE PRESENT-VNAV:

1. LANDING PROCEDURE –INSTRUMENT APPROACH USING VNAV.

Use autopilot to during the approach to give: Autopilot alerts and mode fail indications. More accurate course and glide path tracking. Lower RNP limits.This procedure is not authorized using QFE.

2. INSTRUMENT APPROACH USING VNAV.

VNAV is the preferred method for accomplishing non-ILS approaches that have an appropriate vertical path defined on the FMC LEGS page. Automatic flight is the preferred method of flying non-ILS approaches. Note: Currently, the VNAV PTH mode contains no path deviation alerting. For this reason, the autopilot should remain engaged until suitable visual reference has been established. An approach procedure selected through the FMC ARRIVALS page provides the simplest method of selecting proper waypoints. Procedures in the database comply with obstruction clearance criteria for non-ILS approaches

No waypoints may be added or deleted between the FAF and the MAP – why? FMC “on approach” logic is partially or completely disabled. VNAV obstacle clearance may be adversely affected.

3. TWO TYPES OF APPROACHES IN THE NAVIGATION DATABASE.

Approaches with a glide path (GP) angle displayed on the final approach segment of the LEGS page Complies with final approach step down altitudes.

Approaches where no GP angle is published and where the approach end of the runway is defined by a runway waypoint (RWxx) or a missed approach point fix (MXxx or a named waypoint) exists

Normally a 50-ft threshold crossing altitude is used.

4. GP PUBLISHED.

Approach diagram shows glide path angle and VNAV compatibility.

5. GP NOT PUBLISHED.

6. TYPES OF APPROACHES THAT ARE NOT VNAV PTH-COMPATIBLE

Approaches that do not have a GP angle, and There is no or appropriate RWxx MXxx waypoint with an path terminating at approximately 50ft

above the runway threshold, or The missed approach point is beyond the runway Threshold. Circling-only approaches (e.g., “VOR-A”).

7. USE OF MDA(H)s as DA(H)s When VNAV PTH is used, a slight momentary descent below the published DA(H) during the

missed approach is acceptable. RNP 0.3 capability or less is required. Without a published DA(H), the MDA(H) may be used as a DA(H). Restricted minima will be used for CDFA Approaches and 50ft will be added to the restricted

MDA/DA.