1. International Flight Inspection Symposium
Oklahoma City, OK USA June 2008
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/Raised Coverage Localizer
Hervé Demule, Skyguide Gerhard E.Berz, Eurocontrol Alf W. Bakken, Park Air Systems

2. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

3. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

4. Design Goals 100% compatible with existing airborne equipment
The main lateral coverage region, ±15° shall be 100% compliant with existing ICAO Annex 10 specifications.
25NM within ±10° 2000’
17NM from ±10° to ±15° 2000’
Outside the main lateral coverage region and out to ±35° there must be no false courses or low clearance
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

5. Design Goals
The Clearance CSB field strength shall have a large negative gradient from ±10° to ±15°
Reduction of field strength by approx. 8dB
From ±15° to ±35° the Clearance signal field strength shall be reduced further, but shall be sufficient to suppress the effect of CSB course side lobes.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

6. The design (CSB) The theoretical CSB patterns
CSB patterns calculated with mutual coupling
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

7. The design (SBO) The theoretical SBO patterns
SBO patterns calculated with mutual coupling
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

8. The design (DDM/SDM)
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

9. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

10. Operational Localizer Coverage Requirements to Support Intercept
Avionics (Automatic Flight Control Systems)
Extend use of standardized linear region to support reliable intercept without overshot…
PANS-ATM
Vectoring requirements for intercept
PANS-OPS
Procedure design requirements for intercept lead to IF (2NM minimum)
worst case scenario (high speed / large angle)
Basic ILS Surface Splay
Piloting
Need to arm AFCS LOC Intercept Mode – follows receipt of ATC clearance to intercept
± 5°
± 5°
±15°
See comments to next slide
±15°
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

11. Requirements to Support Intercept
15°
SWISS EMS Flight Data
Intercept Vector
Intercept Lead
AFCS
FAP
LOC
RWY IF
Illustrations use the same sequence as the previous slide:
Start by pointing out AFCS requirements of plus minus 5 degrees (extended use of linear region to 4 plus a little margin) – explain issued associated with this extension (false captures on Annex 10 compliant signal if you wish, but I assume there will not be enough time). (Please check if DDM plot has the right polarity)
Then move to intercept vector, ICAO Doc 4444 prescribes a minimum length of the intercept vector of 1NM. (Note that vectoring is usually done to some short distance prior to the FAP, significantly reducing the time between LOC and GP intercept that is provided to the pilot per PANS-OPS)
The PANS-OPS Intercept lead of 2NM is specified for large angle, high speed intercept. If you take the worst case scenario (shortest possible intermediate segment and final segment, heavy aircraft class), you get to 15 degs. While the IF is here not shown at the shortest possible point (e.g., arrow start does not correspond to bright yellow triangle), note that the drawing is approximately to scale using normal, representative distances – with the exception of having used isosceles triangles instead of circle sectors.
Then explain the distribution of arm points. Note that the data reflects 60’000 global ILS approaches, and praise the analysis that could be done with this data (only due to pilot union agreement and advanced analysis tools).
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

12. Requirements to Support IDENT
IDENT is key driver for LOC Coverage
Without IDENT, Pilot shall not descend on Glidepath (NAV responsibility hand-over)
Taskload study confirmed that IDENT within formal coverage remains possible (high workload / fast geometry)
Operational reality is that IDENT is expected to be available at FL100
Check for Approach
Taskload study looked at all measurable events in cockpit, example here is for a Pilot Non-Flying with the Autopilot OFF (e.g. Pilot NF has more tasks to do).
Tasks include FMS, AFCS manipulations, COM radio transmission, etc., but taskload is only an indirect measure of workload. Short bars: one task, high bars, two tasks (COM radio plus button manipulation).
Analysis was done for worst case scenario: High workload (validated to be steep approach – e.g., more than normal height to lose with little distance to go) and fast intercept geometry, which is a T-approach: entry into TMA on base leg and closing in quickly from entering coverage at 35 degrees to being on centerline (120 seconds generally). Study verified if there were enough IDLE TIME windows of 30 seconds to allow saying that it can be reasonably expected that the crew could complete the IDENT if it had not been done before entering coverage.
Point cloud is when ILS is selected / tuned in cockpit – it is not when IDENT happens, but from then on Pilots will do IDENT if they get it. Our measurements indicate that IDENT can be received as far out as 100NM. Scale on plot goes to 200NM. Germany has had co-channel IDENT cases.
You could note here if you wish that many CAPTURES (LOC and even more Glide) happen outside of formal coverage, probably due to fleet evolution (large jets) over the years.
30 sec task free window
120 sec to LOC TRACK
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

13. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

14. Supporting Technical Validation LOC 16 Zurich: An Initial Problematic Situation
Signal reflections on a building in the Clearance domain, producing,
Clearance / Clearance Interference and
False courses measured by the flight check
0 uA: false courses
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

15. Supporting Technical Validation An Initial Restricted Coverage of +/- 5°
Restriction of the operational coverage: +/- 5° at a range of 25 NM
Outside +/- 5°, possible false courses
The replacement project of the ILS 16 Zurich had to be launched
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

16. Supporting Technical Validation The Replacement Study
The solution consists in:
reducing the incident signal on the building,
thus consequently reducing the reflected signal,
and finally the amplitude of the Clearance / Clearance interference.
Reducing the Clearance incident signal means modifying the Clearance radiating antenna diagram.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

17. Supporting Technical Validation The Chosen System
The reduced/raised coverage localizer at Zurich Airport Runway 16:
The NM 7220B from Park Air Systems
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

18. Supporting Technical Validation Flight Check Results. CSB Patterns
Very good correlation between the measured and simulated CSB patterns
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

19. Supporting Technical Validation Flight Check Results. SBO Patterns
Very good correlation between the measured and simulated SBO patterns
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

20. Supporting Technical Validation Flight Check Results. DDM Profiles
Comparison between the initial and final situations
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

21. Supporting Technical Validation Flight Check Results
RF-Level (in Blue), SDM (in Green) and DDM (in Auburn) Profiles of the Reduced Coverage System at a Range of 17 NM
The problem is solved: no more false course.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

22. Supporting Technical Validation Flight Check Results. IDENT
By flying the standard and published IFR approach procedures, the "flyability" of the standard interception and the availability of the IDENT have been assessed
The IDENT is receivable and useable if the line of sight conditions (i.e. no screening effects due to topographic obstacle) are respected
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

23. Clearance – Course Benefits Simulation
Most critical hangars or buildings tend to be near 12 to 15° from LOC C/L
New clearance design shifts clearance peak inward to ±7-8°
Achievable improvement at one difficult site was demonstrated through site-survey and simulation
Confidentiality requires that we do not say or even hint that this is LHR. But key is to note that the existing ILS is already a good system and optimized to the possible limit.
Mention that upgrade would only require exchange of ADU, if you want.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

24. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

25. ICAO Standardization (1/2)
Current “Solutions” in difficult requirements typically just limit declared coverage
No solutions by design (until now)
Coverage requirements restrain operationally optimal solution (best coverage where needed)
Relaxation of angular limits rejected due to various concerns
Alternative:
Relaxation of lower coverage boundary up to limit
If operational requirements permit
Instrument Flight Procedure needs to be supported
Minimum vectoring altitudes only in line with lowest operational use (e.g., can be higher, depending on local practice)
Does not work everywhere, but more so with use of CDA
Coordinated with ICAO OPS Panel, NSP agreement sought by fall 2008 (published amendment ca. 2010)
Key point to make here is that we want to relax the far out, low coverage corner design drivers and OPTIMIZE coverage to where we really care about it operationally.
NSP accepted that angular relaxation would be ideal solution. Probably good to mention the concerns (FM immunity, increased airport building pressure) even if we don’t agree – but I would not point that out (that we don’t agree – just say these were the concerns).
Note that ZRH ILS meets these requirements using 4000ft HAT, despite difficult terrain, but with a 3m LOC antenna height (if you want)
Note that study of approach geometries using 38 ILS in Europe has been done to show that lowest use of coverage can be supported with raising the lower coverage.
But it does not work in places where ATC descends aircraft down to 2000ft HAT early and far out (such as in Amsterdam, but only say if someone asks). Increased use of Continuous Descent Approaches will make lower coverage boundary relaxation more broadly implementable. Where there is difficult terrain in the approach from an ILS facility point of view, operations tend not to be as eager to descend low early either – natural link.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

26. ICAO Standardization (2/2)
4500ft HAT (MAX)
2000ft HAT
view
Current proposal as preferred version of reduced / raised lower coverage
New guidance seeks to foster dialogue between operational and technical ANSP staff
The view is onto the 17NM range ring cylinder, but showing the 7deg upper limit of coverage out to 25NM. It’s actually a little inconsistent, but I did not want the 10 degree line at 25NM to overlap too much with the 15 degree line at 17NM.
The 2.5 degrees is the angle to the LOC (not the RWY threshold). If descending on a 17NM arc onto the centerline from 4500ft to 2000ft, the descent angle is 2.27 degrees, e.g., someone aiming at 2000ft at centerline at 17NM using 3 degs will be higher (5300ft HAT).
Closer than 17NM achieved coverage goes lower anyway.
I didn’t find the good version of your AutoCAD coverage drawing, if you want you can still change that (no cursor and no 5 deg angle).
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

27. Content Design Operational Requirements
Supporting Technical Validation
ICAO Standardization
Conclusions
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

28. Conclusions (1/2)
The ±15° Reduced/Raised Coverage Localizer has solved the Clearance / Clearance interference on a difficult site: Zurich RWY 16.
The operational and technical experience accumulated has demonstrated that it has been used and operated like any other conventional system.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

29. Conclusions (2/2)
It can also solve Course / Clearance interference in case of a bad course structure caused by Clearance reflections on obstacles located outside the ± 15° region (or even ± 12°)
It represents a major safety improvement compared to conventional ILS with coverage restrictions.
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer

30. Thanks for your attention
Any questions?
IFIS 2008, OKC
Evaluation, Design, Commissioning and Certification of a ±15° Reduced/ Raised Coverage Localizer