European View of Flexible Approaches

Jon Arden

11 March 2004

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?