# Presentation: 334739

## European View of Flexible Approaches

- Jon Arden

- 11 March 2004

## Introduction

- Overview.
- The European Problem.
- Curved Approaches.
- Multiple Approaches.
- Steep Approaches.
- Missed Approaches.

## This is an operators view

- Jon Arden
- 20 years as RAF aircrew.
- Now ATM & Airports consultant with Stasys.

## 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?

## 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.

## 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.

## 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.

## 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.

## 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.

## 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.

## 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.

- Questions or Comments?