Stabilized Constant Descent Angle NPA’sStabilized Constant

Descent Angle NPA’s

OverviewOverview

• What is a Stabilized Constant Descent Angle (SCDA) Non- Precision Approach (NPA)?

• Why do we need it?

• How do we fly it?

• Considerations?

Legal-ApplicabilityLegal-Applicability

• CBAAC No. 0238 is primarily applicable to operators under Subparts 703, 704 and 705 of the Canadian Aviation Regulations (CARs) who may be authorized through Ops Spec 019, 303, or 503 respectively to conduct SCDA NPA procedures at reduced approach ban visibility values RVR, or ground visibility at aerodromes south of 60 degrees North Latitude (60°N Lat), and to use the Minimum Descent Altitude (MDA) as a Decision Altitude (Height) DA(H).

SCDA Training ProgramSCDA Training Program

• The operator should ensure that flight crews receive ground and simulator or flight training that addresses SCDA NPA procedure proficiency.

• The operator should have SOPs incorporating SCDA NPA procedures.

BackgroundBackground

• Precision Approach

– An approach with both lateral and vertical information used to guide the aircraft to a Decision Height

• Non Precision Approach

– An approach with only lateral information used to guide the aircraft to a minimum descent altitude

Decision HeightDecision Height

• A specified height in the precision approach or approach with vertical guidance at which a missed approach must be initiated if the required visual reference to continue the approach to land has not been established.

Minimum Descent AltitudeMinimum Descent Altitude

• The altitude above sea level (ASL) specified in the Canada Air Pilot (CAP) or the route and approach inventory for a nonprecision approach, below which descent shall not be made until the required visual reference to continue the approach to land has been established.

Stabilized approachStabilized approach

• a final approach flown to achieve a constant rate of descent, at an approximate 3 degree descent flight path angle, with stable airspeed, power setting, and attitude, with the aircraft configured for landing.

Types of NPA’sTypes of NPA’s

• Step Down

• Constant Descent Angle

• Stabilized Descent Angle

Traditional NPATraditional NPA

• Step Down Technique

– Also referred to as “Dive and Drive”MAP FAF

What is a CDA?What is a CDA?

• means stabilized constant-descent-angle non-precision approach.

MAP FAF

What is a SCDA?What is a SCDA?

• means stabilized constant-descent-angle non-precision approach.

MAP FAF

The ApproachThe Approach

• Initial Approach– From the IAF to the IF (if defined)– Obstacle clearance 1,000 ft.

• Intermediate Approach– From the IF to the FAF – Obstacle clearance 500 ft.

• Final Approach– From the FAF to the MDA– Obstacle clearance 200 ft.

Traditional NPA WorkloadTraditional NPA Workload

FAF

Final Approach Segment

3.3 nm

Stabilized Constant Descent Final Approach WorkloadStabilized Constant Descent Final Approach Workload

FAF

Final Approach Segment

3.3 nm

Advantages of the SCDAAdvantages of the SCDA

• Increased safety by employing the concepts of stabilized approach criteria and procedure standardization.

• Improved pilot situational awareness (SA) and reduced pilot workload.

• Improved fuel efficiency by minimizing the low-altitude level flight time.

Advantages of the SCDAAdvantages of the SCDA

• Reduced noise level by minimizing the level flight time at high thrust settings.

• Procedural similarities to precision approach operations.

• Reduced probability of infringement on required obstacle clearance during the final approach segment.

Statistics*Statistics*

*Flight Safety Foundation Approach and Landing Accident Reduction Task Force

Stabilized ApproachStabilized Approach• Aircraft on the correct flight path

• Only minor changes required to maintain the correct flight path

• Airspeed between Vref and Vref +20 and power properly set

• Aircraft properly configured for landing

• Sink rate no greater than 1,000 fpm

• All briefings and checklists complete

SCDA CriteriaSCDA Criteria

• The approach is flown to straight-in minima.

• The approach design should permit a final approach segment descent angle of 2.9 to 3.5 degrees.

• The final approach course shall not be more than 15 degrees from runway centreline.

Approach ConsiderationsApproach Considerations

• Don’t forget temperature corrections

• Take minimum altitudes at step-down fixes into account when planning the final descent angle

Missed ApproachMissed Approach

• When flown correctly, the position where a missed approach is commenced following an SCDA NPA to MDA will occur before the published MAP.

• The missed approach climb will normally occur some distance before reaching the published MAP.

Missed ApproachMissed Approach

• Missed approach can begin before the MAP

• Missed approach must begin at the MAP

• For obstacle clearance, delay any turns stated in the published missed approach procedure until the aircraft crosses the MAP

Missed Approach Profile on Step DownMissed Approach Profile on Step Down

Missed Approach Profile on a SCDAMissed Approach Profile on a SCDA

Missed Approach Profile on a CDAMissed Approach Profile on a CDA

Missed ApproachMissed Approach

• Time required for a decision (reaction time);

• Rate of descent at commencement of the missed approach;

• Pilot technique;

• Aircraft performance; and

• Baro altimeter lag.

CAP depictionCAP depiction

Questions???Questions???