1. Stabilized Constant Descent Angle NPA’s
The information provided the following presentation is for information purposes only. IT is always the responsibility of the pilot in command to ensure that they are meeting all required regulations and standards when conducting any flight and that they are ensuring safe flight by maintaining terrain and obstacle clearance.

2. Overview
What is a Stabilized Constant Descent Angle (SCDA) Non- Precision Approach (NPA)?
Why do we need it?
How do we fly it?
Considerations?
Key Teaching Points
Instructors should use the CBAAC No “Stabilized Constant Descent Angle Non-Precision Approach dated as reference.
It is also strongly recommended to any operator planning to adopt the SCDA NPA that they discuss this with their Transport Canada Primary Inspector to ensure that they have met all the legal and operational requirements.

3. Legal-Applicability
CBAAC No 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).
Key Teaching Points
The following items are excerpts from CBAAC No
Applicability
This CBAAC 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).

4. SCDA 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.
Key Teaching Points
An exemption to paragraph (2)(b) of the CARs has been in place since November 1996 to permit operators to use SCDA NPA procedures allowing MDA to be used as a DA(H). The exemption is required in order to accommodate the altitude loss below MDA that will likely occur during a missed approach following a SCDA NPA procedure. With the coming-into-force of the amendments to the Approach Ban, SCDA NPA procedures will be incorporated into the CARs making an exemption unnecessary for Canadian commercial operators.

5. Background 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
Key Teaching Points
There are two methodologies used in the conducting of instrument approaches based on navigation equipment used on these approaches
A precision approach in an approach with both lateral and vertical information used to guide the aircraft to a Decision Height (DH). For example an approach flown using an Instrument Landing System (ILS).
A non precision approach is an approach with only lateral information used to guide the aircraft to a minimum descent altitude (MDA). For example an NBD or VOR approach. .

6. Decision 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.
Key Teaching Points
Reference Aeronautical Information Manual TP 14371E.

7. Minimum 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.
Key Teaching Points
Reference Aeronautical Information Manual TP 14371E.

8. Stabilized 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.
Key Teaching Points
Reference CBAAC No. 0238

9. Types of NPA’s Step Down Constant Descent Angle
Stabilized Descent Angle

10. Traditional NPA Step Down Technique
Also referred to as “Dive and Drive”
MAP
FAF
Key Teaching Points
The concept of “Step Down” is based upon the procedure of getting down to a minimum altitude as soon as possible. The end result is a procedure that entails a non stabilized approach thereby increasing the pilots workload.
Reference TC CBAAC No. 0238
NPAs have traditionally been flown using step-down techniques that result in an unstabilized approach. The descents and level offs result in significant changes in power settings and pitch attitudes, and in some aircraft may prevent the landing configuration from being used until landing is assured. The aircraft is flown to descend to and then level off at the minimum IFR attitudes published for the IAP. In the final segment of the IAP, the aircraft is flown to cross the FAF at the minimum crossing altitude. After crossing the FAF, the aircraft is descended at a rate-of-descent such that the aircraft can be leveled at MDA prior to the MAP. In minimum weather conditions, in order to have an effective chance of completing a normal descent and landing after reaching MDA, the aircraft should be level at the MDA at a distance equal to or greater than the published visibility minima prior to the MAP. In using the step-down technique, the aircraft flies an unstable vertical profile during the final approach segment as it descends and levels off at the minimum altitudes published for the approach, and then if visual descends from MDA to landing.
Using the step-down technique, the aircraft is flown level at minimum altitudes for extended periods of time. The aircraft descends to the initial approach minimum altitude from the enroute structure. The route flown may be a transition route, a direct routing descending to and leveling at the MSA, or using the PT for a course reversal descending to and leveling at the PT altitude. Both MSA and minimum PT altitude provide 1,000 feet ROC. Once inbound to the FAF on the intermediate segment, the aircraft is descended to and leveled at the minimum FAF crossing altitude (provides 500 feet of ROC). After crossing the FAF and on the final approach segment, the aircraft is descended to and leveled at the MDA (provides at least 250 feet of ROC.) The aircraft is flown level at MDA until the runway environment is sighted and a descent to landing can be made, or it reaches the MAP where a missed approach is commenced.
In using the step-down technique, the aircraft flies a series of unstable vertical profiles during the final approach segment as it descends and levels off at the minimum IFR altitudes published for the approach, and then if visual descends from MDA to landing. Using the step-down technique, the aircraft is flown for extended periods at the minimum altitudes, exposing the aircraft to extended periods of time at minimum altitudes above terrain and obstacles. A premature descent or a missed level off exposes the aircraft to a CFIT accident potential.

11. What is a CDA?
means stabilized constant-descent-angle non-precision approach.
MAP
FAF
Key Teaching Points
CDA means constant-descent-angle non-precision approach.
This approach uses the concepts of a constant descent angle approach and when the aircraft descends to the MDA, the aircraft levels off and maintains the minimum altitude until the aircraft reaches the Missed approach point. At this point the aircraft either conducts a missed approach or if the required landing conditions exist, will proceed to land.

12. What is a SCDA?
means stabilized constant-descent-angle non-precision approach.
MAP
FAF
Key Teaching Points
SCDA means stabilized constant-descent-angle non-precision approach.
This approach procedure is the similar to the CDA except that once the aircraft arrives at MDA it will either start a missed approach or if the required visual conditions exist, the aircraft will land. The aircraft does not level off and continue to the MAP.
Therefore the basic difference between an CDA and A SCDA is the fact that there is no level off in the SCDA. If the aircraft levels off it has now become an unstabilized approach, and must be referred to as a CDA only.
The need for a stabilized final approach during NPAs has been recognized by the International Civil Aviation Organization (ICAO) CFIT Task Force as a means to prevent CFIT accidents.
The step-down technique (presumed by the procedure design) may have been appropriate to early piston transport aircraft, but most modern jet transport aircraft are much faster, heavier, have greater inertia and are less maneuverable than early aircraft. These factors make late changes in vertical profile undesirable and even dangerous. Many operators require their crews to use a stabilized technique, which is entirely different from that envisaged in the original NPA procedure design. A stabilized approach is 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. The safety benefits derived from a stabilized final approach during an NPA have been recognized by most organizations including ICAO, the Federal Aviation Administration, and Transport Canada Civil Aviation. CBAAC No. 0238

13. The 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.
Key Teaching Points
Approaches are designed with the following criteria as far as obstacle clearance.

14. Traditional NPA Workload
FAF
Key Teaching Points
A traditional step down method of flying a non precision approach will cause the flight crew to change the aircrafts power, trim and attitude numerous times during the critical phase of descent. Each of the stars represent a period of increased workload for the flight crew.
Final Approach Segment
3.3 nm

15. Stabilized Constant Descent Final Approach Workload
FAF
Key Teaching Points
Reference TC CBAAC No. 0238
SCDA NPA
The aim of an SCDA NPA procedure is to minimize the vertical manoeuvring required while flying most NPAs from the final approach segment through to touch down. The goal is to achieve a final approach vertical path that approximates that of a normal glide path. An SCDA NPA procedure allows certain NPAs to be flown using the MDA as a DA(H).
Using the SCDA NPA procedure, the aircraft is not flown at minimum altitudes for extended periods of time. If the route flown intercepts the intermediate approach segment, then a higher enroute altitude can be maintained until an approximate 3-degree vertical descent path is intercepted and a continuous descent to MDA can be made. If a course reversal using a PT is required, the aircraft can be flown at or above the minimum PT altitude until the 3-degree vertical descent path is intercepted and a continuous descent to MDA can be made. No later than crossing the FAF, the aircraft descends stabilized on the planned constant descent angle
configured for landing, with stable airspeed, power setting, and attitude. The aircraft is descended towards MDA until the runway environment is sighted and the descent continued to landing, or until it reaches MDA (treated like a DA(H)) where a missed approach is commenced.
Final Approach Segment
3.3 nm

16. Advantages 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.
Key Teaching Points

17. Advantages 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.
Key Teaching Points

18. Statistics*
Key Teaching Points
The “Flight Safety Foundation Approach and Landing Accident Reduction Task Force” found that in the case of Controlled Flight Into Terrain accidents reviewed durin their study, 57% were during Non Precision Approaches.
*Flight Safety Foundation Approach and Landing Accident Reduction Task Force

19. Stabilized 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
Key Teaching Points

20. SCDA 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.
Key Teaching Points
The SCDA NPA procedure is normally applicable to NPAs that meet the following three criteria:
• The approach is flown to straight-in minima. (SCDA is not normally applicable to circling approaches where the aircraft has to level at MDA and a circling procedure flown before a descent to landing can be made.)
• The approach design should permit a final approach segment descent angle of 2.9 to 3.5 degrees. (NPA approach design criteria permit a final approach segment with a descent gradient up to 3.77 degrees. Therefore, there are a few NPAs with steep descent gradients that exceed 3.5 degrees, for which the SCDA technique would not be appropriate. New approach design criteria for NPAs with vertical guidance limit the descent angle to 3.5 degrees or less.)
• The final approach course shall not be more than 15 degrees from runway centreline. (NPA design criteria permit straight-in minima to be published for IAPs with final approach courses up to 30 degrees from the runway centreline. The SCDA approach procedure is not normally applicable to straight-in approaches with final approach courses that exceed 15 degrees from the runway centreline, in order to reduce the requirement for lateral manoeuvring during the transition from approach to landing.)
An SCDA NPA final approach descent is flown with a planned SCDA of not less than 2.9 degrees and not greater than 3.5 degrees from the FAF to a nominal landing runway threshold crossing height of 50 feet. The angle flown is selected to ensure that minimum FAF crossing altitude and any step-down altitudes between the FAF and the MAP are respected.

21. Approach Considerations
Don’t forget temperature corrections
Take minimum altitudes at step-down fixes into account when planning the final descent angle
Key Teaching Points
Ensure that when planning the descent angle, ensure that you take into consideration any temperature issues.
Also when calculating the descent angle and altitudes ensure that you take into account all minimum altitudes at each step down segment. Ensure that you do not set up an descent angle that will cause you to violate these minimum altitudes. The altitudes and timings set up on the approach plates take these minimum altitudes into consideration.

22. Missed 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.
Key Teaching Points
If you are a commercial operator who meets the Transport Criteria, then you are allowed to use the MDA as a DH. If your are not authorized then you need to start your missed approach prior to reaching the MDA, taking into account the loss of altitude from the start of the missed approach procedure to the point where the aircraft starts to climb. A rule of thumb is considered to be 50 feet.
Let’s assume your MDA is 500 feet then you would start your missed approach at 550 feet, using the above rule of thumb. However, as an authorized commercial operator, you would start your missed approach at 500 feet.

23. Missed 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

24. Missed Approach Profile on Step Down
Key Teaching Points
This slide demonstrates the traditional approach profile where the aircraft is maintaining the Minimum Descent Altitude until the time is up. Then the crew commences the missed approach.

25. Missed Approach Profile on a SCDA
Key Teaching Points
In the case of an SCDA NPA procedure, the crew would commence the missed approach upon reaching the MDA. In other words using the MDA as a DH.

26. Missed Approach Profile on a CDA
Key Teaching Points
A third option would be to fly the CDA NPA and when approaching the MDA, level out and fly the minimum altitude until the time is up. However when you analyse this method you quickly realize that on a normal approach you would probably only be level for a few seconds. You must remember that when you reach the MDA on the approach profile you are in a position to land straight ahead, as if on a normal visual of ILS approach. Therefore leveling off doesn't really provide you with much benefit.

27. Missed 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.
Key Teaching Points
Items to consider when conducting a missed approach are the following:
Time required for a decision (reaction time);
Rate of descent at commencement of the missed approach;
Pilot technique;
Aircraft performance; and
Barometric altimeter lag.

28. CAP depiction
Key Teaching Points

29. Questions???
Key Teaching Points