1. European View of Flexible Approaches Jon Arden 11 March 2004

2. 2 Introduction o Overview. o The European Problem. o Curved Approaches. o Multiple Approaches. o Steep Approaches. o Missed Approaches.

3. 3 This is an operators view o Jon Arden o 20 years as RAF aircrew. o Now ATM & Airports consultant with Stasys.

4. 4 Overview o Findings based on ongoing studies into GBAS utility. o ILS good system but arguably lacking in terms of: o Flexibility. o Interference. o Obstacle Limitation. o Great interest in GBAS: o Considered to have similar characteristics. o Single final approach path to a runway. o Offers more flexible operations through provision of variable curved approaches and variable glide slopes. o Is flexibility required and will the customer pay for it?

5. 5 The European Problem o An extremely congested piece of airspace: o LHR, CDG, Amsterdam, Frankfurt. o Intensive Military training. o National boundaries. o Weather factor. o Major issues for European airlines, ANSPs, regulators: o Cost. o Delay. o Capacity. o Environment. o Safety. o Cost.

6. 6 Curved Approaches (1) o Flexibility in definition of lateral approach path offers benefits. o Use of GBAS as direct ILS replacement simplifies cockpit interface requirement, however: o Autopilot certification needed - cost could be prohibitive. o Obstacle clearance: o Current model drive by ILS approach sectors. o Footprint would have to be redefined to cover curved approach area. o Problem of existing buildings and controlling future.

7. 7 Curved Approaches (2) o Perceived benefits for quiet airports where curved approaches could be flown from differing directions. o Mixed views on integration at busy airports: o Advantages: o Work arounds for environmental restrictions. o Disadvantages: o Controller workload during sequencing. o Limited utility in poor met conditions. o Reasons for resistance needs further study, possibilities: o Culture – resistance to change. o Lack of visibility, education of potential controller tools.

8. 8 Multiple Approaches o Problem of multiple approaches to twin runways tends to be one of wake vortices restrictions extending separation. o Assessed Frankfurt HALS/DTOP o Multiple approaches are currently in use. o Use of displaced threshold for light approaches, effectively provides a third runway. o System appears to be successful. o Questionable whether GBAS offers anything in solving the wake vortices problem, however: o GBAS may offer cost benefit in replacing the many ILS installations required, subject to reversion requirements. o May also offer advantages in ease of switching approaches between runways.

9. 9 Steep Approaches o Rarely desirable for large aircraft, due to passenger comfort and aircrew human factors o Airbus are currently limited due to glideslope limitations of the autopilot. o Cost of modification/recertification unclear. o Specific training required for controllers and for aircrew. o Again some resistance evident. Could be cultural. o For runways with multiple glideslopes: o Different lighting will be required for each glideslope. o Tower controller’s task of monitoring aircraft may be more difficult.

10. 10 Multiple Missed Approaches o MAs are treated as emergency situations, and thus preferable to have only one simple choice for a procedure to be followed. o They do not traditionally use the ILS back beam. o GBAS could provide great utility and simplify the procedure. o Agreement on requirement for non-satellite based back-up required.

11. 11 Conclusion o Studies currently show the obvious utility of GBAS. o However there is some resistance and scepticism on flexible approaches: o This may be resistance to change, but will still need to be addressed. o Obvious requirements for training and controller tools to aid deployment. o Generally good reaction to utility of multiple approaches and missed approaches. o Less so with regards curved and steep approaches. o There appear to be differing views between controllers and pilots. o As always cost will decide.

12. 12 Questions or Comments?