Advanced Speed Guidance for Merging and Sequencing

Techniques

Chris Sweeney, 2006-2007

MITRE Corporation

Center for Advanced Aviation System Development

Mclean, VA

Introduction

• Research experts have been working to create software that can be put aboard aircraft to help Air Traffic Controllers manage merging streams of traffic

• The goal is to keep the aircraft properly spaced as they arrive at the airport

• Current algorithms estimate a speed to fly so that the aircraft will be properly spaced

• Speed to fly is sent to the pilot as a recommendation• Goal of this project is to create a product for UPS to use• UPS has many airplanes coming into airports at night so

this software will help Air Traffic Controller manage the large amounts of aircraft

Background

• New technology called ADS-B enables aircraft to send trajectory data directly to another aircraft

• With this advancement, aircraft can send data that is necessary to use this data to calculate a recommended speed to fly

• ADS-B communicates very frequently, so the recommended speed to fly can be recalculated often to improve accuracy

Current Algorithms

• Uses time based spacing, how many seconds behind lead aircraft

• Time based spacing naturally compresses and expands as speed changes

• Desired spacing value is the ideal spacing (normally 120 seconds)

• Spacing error is the difference between current spacing value and desired spacing value

Current Algorithms

Current Algorithm

• A more accurate method is to save trajectory data of the lead aircraft

• Look at lead aircraft’s position at t-desired spacing seconds ago

• This position is where you want to be

• Spacing error is the difference between current position and that position

Current Algorithms

• Goal of the algorithm is to fix the spacing error

• Recommended speed to fly is the estimated speed that will correct the spacing error

• Oscillations as a result of small speed or altitude changes in the target aircraft are reflected in the recommended speed to fly

Problems

• Current algorithms present too many speed commands

• Overwhelms and distracts the pilot• Can become unstable• Constantly changing speed recommendations

are obnoxious to a pilot• Surveys have shown that pilots are more likely

to ignore the recommendations if they are constantly changing or oscillating frequently

My Project

• Reduce the number of speed commands to a manageable number

• Do this while maintaining proper spacing

• Make an Improved Speed Calculation algorithm

• Create filters and quantizers to reduce the number of commands

Improved Speed Calculation

• When the lead aircraft makes a large speed change, the normal algorithm takes many small consecutive steps (blue line)

• This can be reduced to one large command (green line)

Improved Speed Calculation

• Start at t-desired spacing• Calculate the acceleration at that point• If the acceleration is above a threshold,

then the change is large enough that we will run the improved algorithm

• Progress to next data point• Run the algorithm while the acceleration at

the current data point is above the threshold

Improved Speed Calculation

• When the algorithm stops– Calculate duration: difference between time at data

point where it stops and t-desired spacing– Calculate magnitude of change: difference speed at

data point where it stops and speed at t-desired spacing

• Recommended speed to fly = current speed + magnitude of change

• Recommended speed to fly stays displayed for “duration” seconds

Improved Speed Calculation

Experiments

• MITRE has a flight simulator in the Air Traffic Management Lab

• We recorded a flight from start to finish• Ran a simulation where that flight was used as

the lead aircraft and we were the trail aircraft• Simulation featured a focus on human factors

such as reaction time• 45 minute real-time simulations run 10-15 times• Fast time simulations run 5-10 times

Experiments

Above: The cockpit of MITRE CAASD’s flight simulator in the ATM lab

Left: Speed Recommendations are displayed on the left side of the CDTI

Results

• We consistently observed a reduction in speed recommendations of 50%

• During major speed changes, what would normally be 9-12 recommendations were reduced to 1 large recommendation

• Even when speed changes were not large enough for the improved algorithm to run, the filters and quanizers significantly reduced the number of recommendations

Implications

• During standard arrival procedures, aircraft significantly reduce speeds

• Prior to the Improved Speed Algorithm, simulations could not include arrivals because the results were extremely unpleasant

• This breakthrough allows MITRE to run a broader range of tests from departure to arrival without interruption

• This is a major step to preparing the product for field testing

Reflections

• Extremely valuable to see how computer science and engineering can be applied to a real life product

• Advice: read carefully, try to think about things in a larger scope while maintaining a detailed understanding

• Work Environment: There were several TJ grads at MITRE so it was very easy to relate to people. No real adjustment was necessary other than maintaining acting professional

• Remember, you’re representing yourself, the school, and your demographic!

Acknowledgements

• H. Peter Stassen

• Matthew Pollack

• Kelley Connolly

• Urmila Hiremath

• Mr. Latimer

• Mr. Pearce

Works Cited• EUROCONTROL, ”CoSpace 2005-ASAS Sequencing and Merging:

Flight Deck User Requirements Version 2.1”, EUROCONTROL, 2006.

• E. Hoffmann, N. Pene, K. Zeghal, ”ASAS Spacing User Requirement Document”, EEC document version 2.0

• I. Grimaud, E. Hoffman, L. Rognin, K. Zeghal, ”EACAC 2000 Real-Time experiments: Pilots perspectives”, EEC Report version 3.0

• EUROCONTROL/FAA, ”Principles of Operations for the Use of Airborne Separation Assurance Systems”, EUROCONTROL/FAA Cooperative R&D Edition 7.1, 2001

• J. Hammer, ”Preliminary analysis of an approach spacing application”, FAA/Eurocontrol R&D committee, Action plan 1, ASAS Technical Interchange Meeting, 2000