Stabilized approaches

[Captain Smiley]

I am looking for some articles etc on stabilized approaches and constant angle non precision approaches.

Anyone have any website references?

Thanks.

[aldo]

Dear Captain,

on the website www.utem.com you can download a booklet about CDAP, in pdf format. It is from Captain Mike Ray, writer of checkride manuals.
I hope that it can help you.
Regards,

Aldo

[john_tullamarine]

A regular topic of conversation on PPRuNe ... when the facility is back, do run a search on PPRuNe and you will have a fair bit of reading to do.

[safetypee]

From the Flight Safety Foundation's ALAR Tool Kit

Elements of a Stabilised Approach
“All flights shall be stabilised by 1,000 feet height above touchdown (HAT) in instrument meteorological conditions (IMC) and by 500 feet HAT in visual meteorological conditions (VMC).” An approach is considered stabilised when all of the following criteria are met:
1. The aircraft is on the correct flight path;
2. Only small changes in heading and pitch are required to maintain that path;
3. The aircraft speed is not more than V REF + 20 knots indicated airspeed (KIAS) and not less than VREF ;
4. The aircraft is in the proper landing configuration (approach configuration for small twins);
5. Sink rate is maximum 1,000 feet per minute; if an approach requires a sink rate greater than 1,000 feet per minute, a special briefing should be performed;
6. Power setting appropriate for configuration and not below the minimum power for approach as defined by the aircraft operations manual;
7. All briefings and checklists have been performed;
8. Specific types of approaches are considered stabilised if they also fulfil the following: instrument landing system (ILS) approaches — must be flown within one dot of the glideslope or localizer; a Category II or III approach must be flown within the expanded localizer band. Visual approaches — wings must be level on final when the aircraft reaches 500 feet HAT. Circling approaches —wings must be level on final when aircraft reaches 300 feet HAT; and,
9. Unique approaches such as the “old” Hong Kong Airport and the DCA (Washington, D.C.) river visual approach to Runway 18 require a special briefing.

[seacue]

As I read through the list I kept saying "I know of an approach that can't meet these requirements", and then I reach Item 9 - the DCA approach. And it's done by 20 or 30 mainline jets per hour on many days. BTW, Runway 18 at DCA was renumbered 19 a few years ago.

Approach to Rwy 19 (http://users.erols.com/rcarpen/dca021110.jpg)

[alf5071h]

ICAO reference:

PANS-OPS (Doc 8618), Volume 1, Amendment 11, applicable 1 November 2001
Part IX Operational Flight Information, new Chapter 3
Chapter 3
STABILIZED APPROACH PROCEDURE

3.1 GENERAL
3.1.1 Maintenance of the intended flight path as depicted in the published approach procedure, without excessive manoeuvring as defined by the parameters in 3.2.1, shall be the primary safety consideration in the development of the stabilized approach procedure.

3.2 PARAMETERS FOR THE STABILIZED APPROACH
3.2.1 The parameters for the stabilized approach shall be defined by the operator’s standard operating procedures (Part XIII, Chapter 1). These parameters shall be included in the operator’s operations manual and shall provide details regarding at least the following:
a) range of speeds, specific for each aircraft type;
b) minimum power setting(s), specific for each aircraft type;
c) range of attitudes, specific for each aircraft type;
d) crossing altitude deviation tolerances;
e) configuration(s), specific for each aircraft type;
f) maximum sink rate; and
g) completion of checklists and crew briefings.

3.3 ELEMENTS OF THE STABILIZED APPROACH
3.3.1 The elements of a stabilized approach shall be stated in the operator’s standard operating procedures. These elements should include as a minimum:
a) that all flights should be stabilized according to the parameters in 3.2.1, by no lower than 300 metres (1 000 ft) height above threshold in instrument meteorological conditions (IMC); and
b) that all flights shall be stabilized according to the parameters in, 3.2.1, by no lower than 150 metres (500 ft) height above threshold.

3.4 GO-AROUND POLICY
3.4.1 An operator’s policy should be included in the standard operating procedures that in the event of an approach not being stabilized in reference to the parameters in 3.2.1 or the elements in 3.3.1, or becoming destabilized at any point during an approach, a go-around is required. Operators should reinforce this policy through training.

Note.— Preparation of an Operations Manual (Doc 9376), Chapter 8, 8.6.13 includes general considerations about stabilized approaches.


Also see Flight Safety Foundation:
Special FSF Report: Killers in Aviation: FSF Task Force Presents Facts about Approach-and-landing and Controlled-flight-into-terrain Accidents. (http://www.flightsafety.org/pubs/fsd_1999.html)
Flight Safety Digest November 1998–February 1999

[OzExpat]

Yes, there's been a few threads on this topic in the last couple of years. Most have dealt with it as CANPA, or some other term that essentially means the same thing. Some of these threads have horrified me, so I hope that the reference quoted by alf5071h sinks in with people.

The fact is that a NPA procedure is likely to always be a manoeuve based on a series of minimum altitudes all the way to the MDA. Therefore, how the pilot elects to execute the approach is only optional to a certain extent. The quoted reference is saying that you still cannot bust any of the procedure altitudes, especially not the MDA.

So, for the benefit of anyone who still thinks that they can fly CANPA all the way to MDA and THEN initiate a missed approach... you're playing with fire and, sooner or later, you WILL get burned. The problem with this is that it unnecessarily spoils the day for the poor bugga who designed the procedure. He (or she) still has to front the Magistrate to explain that the design of the procedure complies with Pans Ops (or TERPS, as applicable) criteria.

Even after the designer is exonerated - months or YEARS later - that person has, understandably, a crisis of under confidence. And it's all because some idiot thought he knew better.

I'm not pointing the bone at anyone here, merely trying to give the procedure designer's perspective. Pilots need good approach procedures and, therefore, you need procedure designers who not only know and understand the criteria, but have the confidence to apply it in the trickiest of situations. After all, anyone can design a procedure to a place when there's no obstacles to worry about.

Pans Ops provides for NPA procedures that employ a glide slope and, therefore, also account for "sink thru" at MDA. If you're using one of these procedures, that's fine. If not, please don't expect to be able to safely "sink thru" a MDA on any other type of NPA.

Sorry if this sounds a bit strong in tone, but I've stayed silent on similar threads when I probably should've piped up.

[alf5071h]

Good points OzExpat, but more emphasis is still required on how non precision approaches should be flown.

Captain Smiley asked for information on stabilized approaches and constant angle non precision approaches. The critical issue is that both must go together as one in the same procedure. There have been many accidents where crew have flown NPAs with an ILS type of operation; configuring the aircraft and decelerating whilst descending, and then forgetting that they are responsible for judging / controlling the ‘glidepath’. If an NPA is flown in VS mode (FD, autopilot, or crew computation) then as the aircraft decelerates the required vertical speed reduces. Simple, obvious, basic … but so often forgotten; an error, which allows the aircraft to descend below the optimum glidepath.

A NPA requires special briefing with respect to the method of controlling the aircraft to achieve a constant angle approach and to achieve speed / configuration stability on which to judge corrections to the approach. Without these the approach is like a moving target, the crew may loose position awareness, or lack knowledge of distance or time to go; all of which add to workload and increase the operating risk. And do not forget that an ILS with GS inop is a NPA.

All NPA charts should have a range / altitude table so that crews can judge how the accurately the glidepath is being followed; crews should always estimate the required vertical speed and time to visual descent point or MAP. Charts should also show the VDP on the profile or the distance to go table.

Re European stabilized approaches and constant angle non precision approaches; the JAA Ops / all-weather ops groups were drafting new information for JAR-OPS 1 subpart D/E to be published as an ACJ. When I last viewed the information it was an awful mess mixing up constant angle with stabilized parameters. It also suggested that crews would have to have extensive training and yearly practices / assessments of how to fly a stabilized approach; if this isn’t basic every day flying, controlling speed, altitude, and VS, then what standard of crew expertise is the JAA using? Has this new information reached JAR-OPS 1 yet? Has anyone any update on the so-called harmonization of CANPA with the FAA?


Edit:
More links:
Other Articles - Constant Angle Non-Precision Approach (http://www.cockpitgps.com/) this document also has other links, some pro CANPA and some cons, read these carefully and relate them to GA / commercial operations as appropriate.

An Alternative to Dive and Drive (http://www.aircraftbuyer.com/learn/train03.htm)

An interesting view from virtual reality CANPA (http://www.scandva.org/ops/proc/vor_approach.htm)
JAA RNAV info including approaches: see Day Three (http://www.ecacnav.com/P-RNAV/workshop2003/presentations.htm)