# Presentation: 529364

## Green Approaches:4D-Trajectory Enabled Continuous Descent Approaches

**Keith Wichman -- Smiths Aerospace**
**FAA New Technologies Workshop III**
**9-10 January 2007, Arlington Virginia**

## Example: Aircraft capability

**Example: Aircraft capability**

**Thrust**

**Thrust**

**Entire descent &  approach:**
**Least possible thrust**
**Highest possible altitude**

*Why are A-CDAs not much practiced?*

**Todays std practice**
**6~10 step downs**

## Why are CDA’s not used wholesale?

_**Myth**_**: “CDA’s reduce capacity”**
- Idle descent vertical and time profiles can vary widely from aircraft to aircraft
- This uncertainty drives need for ATC to block large chunks of airspace
**Thus, CDA’s practiced today generally off-peak hours and/or sub-optimal descents (least-common-denominator fixed vertical profiles)**
_**Solution**_**: Marriage with 4D-trajectory downlink, and if needed, onboard time-guidance (RTA) functionality supplies ATC with observability and predictability to use CDA’s during dense operations**
_**Requirements**_**: **
- Aircraft – 4D FMS’s already predict reliable 4D Trajectories (4DT) and guide to Required Times of Arrival. Need appropriate downlink of the 4DT
- ANSP – Operational shift toward Trajectory Based Operations (TBO) to incorporate the 4DT and the development of necessary support applications

## Trajectory-Based Operations

**Basis for strategic planning and tactical operations including separation management.**
- Key concept element for the USA’s **NGATS** and Europe’s **SESAR**
- Four-dimensional trajectory (4DT) is the cornerstone of Trajectory-Based Operations for improved predictability
- “Open-ended” flight maneuvers (such as vectoring) reduce predictability.
- “Closed” trajectory-based maneuvers improve predictability.
**While designed to optimize an individual flight and reduce pilot workload, modern FMS’s offer much capability that could be tapped by ATM to optimize the whole system. Trajectory-based operations seeks to exploit this functionality.**

## The Paradigm Shift

**Notes:**
It is useful to leave the microscopic view, sit back and take a view from some distance to better appreciate the overall effect of all the evolution steps, and realise that, while preserving the continuity of the real-time operations during the transition period, we really aim at a significant paradigm change for ATM.
The fundamental change in ATC methods and controller’s role over the last 30 years has been to move from procedural to radar control since it allowed to get rid of the difficult exercise to imagine the position of aircraft. This was a tremendous revolution for Air traffic Controllers, which generated new responsibilities related with directing the Air traffic and in some specific cases moved  the pilot responsibility for navigating the aircraft and maintaining separation from the ground, to the Controller. 
In my view, the next such step, even if it comes progressively, is an ATC based on trajectory data, in the sense that accurate and complete information would be available on the future position of aircraft, making it possible to plan ahead, identify and resolve in advance potential conflict problems, and leading to new working methods supported by computer assistance and data-link.
The roles and responsibilities of controllers and pilots will evolve in line with:
New  ways to present the traffic situation, new data being exchanged on the one hand; and
New working methods, including team organisation, or different responsibility sharing on the other hand.
It is foreseen that at the horizon of the concept, the human being, controller and pilot, will still be ultimately responsible for real-time decision-making, and that task sharing will be even more focused on exploiting the strengths of human capabilities. I’m sure we are progressing for a safer and more efficient Air Traffic Management System but I’m also sure that it is imperative that Controllers and Pilots need to receive the support they need to continue serving as the last line of defense of the system. 

## Roadmap

**NGATS and SESAR aim to set vision and path to achieve 4DT ATM**
**In-service operational evaluations represent “forays” into the future:**
- Validation of concepts
- Validation of benefits
- Results and data informs decisions of political activities (NGATS, SESAR)
**These vanguard activities require effective teaming across domains**
- ANSP (and equipment suppliers)
- Operators (and OEM + suppliers)
- Airport Authority
**... ****basis for the integrated system seen by NGATS and SESAR.**
**The European Commission’s **_**NUP2+ Program**_** is presented here.**

**“****Triplets”**

## Terminal Movements with Trajectory-Based Operations

**Increased arrival/departure throughput and efficiency.**
- Increased predictability
- Reduced track distances
- Reduced voice communications & vectoring
**More efficient vertical profiles with reduced fuel consumption.**

**Metering Fix**

## FMS and Avionics

**FMS and Avionics**

## Required Time of Arrival

**Algorithm is based on speed variation.**
- Fixed lateral path
- Fixed cruise altitude
**Required Time of Arrival is enabled for any point in the flight plan.**
- Available on 737 aircraft since 1986.
- Demonstrated performance in trials with SAS in 2001.
**Future enhancements:**
- Improved control to the runway accounting for fixed speed segments.
- Compensation for control error tolerance when reporting trajectory early in the flight.
- Include lateral offset and/or cruise altitude variation when additional delay is required.

## RTA to the Runway

**Results were obtained in trials with SAS in 2001 (33 flights).**
**Performance is better when controlling to start of arrival due to more speed-control authority.**
**Limited control late in descent due to constrained speed.**

| RTA Target | Max | Mean | STD |
| --- | --- | --- | --- |
| Top of STAR | 7 Sec | 4.8 Sec | 2.7 Sec |
| Runway | 21 Sec | 12.7 Sec | 7.3 Sec |

## ARINC 702A-1 Trajectory Bus
Aircraft current-state information 2Hz
Aircraft 4D trajectory predictions (Intent)
Each minute or when FP changes
Full trajectory to runway
Includes vertical wpts and turns
Dedicated ARINC 429 Bus
As per ARINC702A-1

**Aircraft current-state information 2Hz**
**Aircraft 4D trajectory predictions (Intent)**
**Each minute or when FP changes**
**Full trajectory to runway**
**Includes vertical wpts and turns**
**Dedicated ARINC 429 Bus**
**As per ARINC702A-1**

**Intent Bus in B737 U10.6 FMS**

**ARINC429 **
**Trajectory Bus**

**Current A/C State and **
**Trajectory Predictions**

**ACARS messages added for interim use in flight trials **
**By REQ from ATC **
**One-time or periodic downlink**

**First application in 2005 –****Provide FMS 4D trajectory to ATC!**

**ACARS**

**in 2007!**

## ARINC 702A-1 4DT Data for Stockholm to Malmo Flight

**Route: ESSAESMS10**
**---------starts here-----------**
**1,,,N59397E017581.**
**1,R,113,N59401E018009,108,090122.**
**C,,,N59376E018019,500,090227.**
**0,R,557,N59359E017585,769,090306.**
**0,L,934,N59302E017443,1279,090456.**
**0,,,N59070E017184,2511,090907.**
**0,R,1893,N59044E017155,2604,090932.**
**B,,,N58515E016548,3032,091149.**
**8,,,N58380E016335,3500,091408.**
**0,,,N58366E016312,3500,091423.**
**0,,,N57592E015342,3500,092051.**
**0,,,N57388E015041,3500,092420.**
**0,,,N57024E014122,3500,093032.**
**0,,,N56455E013489,3500,093323.**
**9,,,N56354E013354,3500,093504.**
**0,L,981,N56345E013340,3450,093513.**
**B,,,N56295E013331,3223,093553.**
**0,L,1249,N55550E013268,2010,094058.**
**1,R,406,N55247E013335,1002,094623.**
**1,R,215,N55210E013322,886,094712.**
**C,,,N55189E013229,500,094951.**
**0,L,171,N55198E013275,459,095034.**
**0,,,N55276E013235,148,095357.**
**0,,,N55314E013227,29,095528.**
**1,,,N55329E013212:00002926**
**        ****EOT finalLDU=1, CRC=3483**

- 0,L,934,N59302E017443,1279,090456

## NUP 2+ Partners

- Airlines

- Airports

- Industrial
- group

- ANS

**NUP 2+ Partners**

## NUP2+ Trajectory Usage

- AOC
- SAS
- RC Hermes

- ACARS
- ARINC 702A-1 standard

- Flight operations began
- January 19th,  2006

## Trajectory Reporting

**ARINC 702A Supplement 1 was defined for early implementation.**
- Implemented in 737 FMS with U10.6 software – dedicated ARINC 429 bus.
- ACARS downlink of trajectory intent information as interim datalink.
- European Commission (EC) supported activity, NUP2+, in Sweden and Austria.
**Operational evaluations began in October 2005 including:**
- RTA contracting to the runway.
- Green Approaches (CDAs) with FMS 4D trajectory to preserve capacity.
- Slot Swapping
- Ground Holding
**First air/ground operation connectivity of FMS 4DT with Arrival Manager...**
- Airlines are deriving demonstrable benefits (punctuality, fuel).
- Operations now in medium traffic conditions... moving toward peak traffic.

## First 4D FMS Trajectory Downlink

**First 4D FMS Trajectory Downlink**

## Controlled Time of Arrival

**Generated by a Time-Based Metering system to merge traffic from metering fixes to a runway.**
- A key capability of an FMS is to “self-deliver” to a specified waypoint at a Required Time of Arrival (RTA).
- The FMS efficiently operates a flight with a user selected Cost Index (CI) and a Continuous Descent Approach (CDA).
- Accurate ETAs need to be downlinked from the aircraft to close the loop with ground control.

## ANSP Integration of 4DT in Arrival Management

## Strategic Communication Description

**Lift-Off**

**Climb**

**En-route**

**Descent**

**Strategic Communication Description**

## Example from live trial

- Via 4DT downlink SAS075 confirms GA HAMMAR1V with ETA 06:49

- Via 4DT downlink SAS2059 confirms GA HAMMAR1V with
- ETA 06:50

- Controller want 180 second separation. Send RTA 06:47:00 to
- SAS075

- Reply: RTA unachievable

- Sends RTA 06:48:00 to SAS075 and RTA 06:51:00 to SAS2059

- RTA Accepted

- RTA Accepted

- In the new downlinked 4DT messages, the time separation at HMR had increased from 1 to 2 minutes

- Controlling to time resulted in physical separation of 10NM at OM

**Benefits of the 4DT Approach**

- 1st 4DT downlink 19th of October 2005
- 1st 4DT Flight 19th of January 2006
- General 4DT operation from 26th of March 2006

## NUP 2+ ResultsFuel Savings CDA vs Standard Approach

**NUP 2+ Results****Fuel Savings CDA vs Standard Approach**

## TRANSCAP Noise results

**Notes:**
This slide shows the results of a Noise study that was carried out of green approaches to Stockholm Arlanda, runway 26. The results from this study showed that peak noise was down around 5 dB and the area affected by ‘annoying’ noise was reduced considerably.

## Next step Arlanda: Mixed mode operation

**Next step Arlanda: Mixed mode operation**

- 5NM

- 10NM

- 160kts OM

## Next step Arlanda: Mixed mode operation

**Next step Arlanda: Mixed mode operation**

## SAS Sweden Experience from 800+ Green Approaches

**More than 650 Green Approaches flown to date... (and counting) resulted in:**
- 204 Metric Ton CO2 reduction yearly
- 715 kg of NOx reduction yearly
- 130,000 kg of fuel saved
**SAS-Sweden 36,000 Green Approaches per year into Stockholm alone**
- $5.8M fuel reduction yearly
- 23,000 Metric Ton CO2 reduction yearly
- 79 Metric Ton of NOx reduction yearly
- Large noise reductions (being quantified)
** **
**SAS and LFV expanding Green Approaches throughout domestic Sweden**
** **

## NUP2+ Steps for 2007

**Install VMMR to downlink 4DT via ADS-B**
**Install EFBs for surface movement guidance operations**
**Install enhanced FMS software for better predictions and RTA**
**Conduct controller simulations with mixed equipage and high traffic**
**Operate regularly in peak traffic (>57 mvts/hr), mixed equipage, CDAs and validate capacity unchanged or increased.**
**Infuse results into JPDO-NGATS and SESAR**
**Also...**
**Plans firming to expand the operations in 2007 to adjacent regions in “core-Europe” in order to begin developing end-end benefits to participating airline operations. **