European View of Flexible Approaches

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

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

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

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

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

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

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

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

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

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

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

12. Questions or Comments?