US to smooth global adoption of four-dimensional trajectory flight

Aviation authorities in the United States are to conduct their own series of four-dimensional trajectory demonstration flights building on the work of their European counterparts.
Four-dimensional trajectory management is a precise description of the aircraft path derived from the current flight plan (latitude, longitude, altitude) and the additional component of time.
Trajectory-based operations (TBO) are a key objective for both NextGen and SESAR ATM modernisation programmes in both the US and Europe and harmonising 4D trajectory management is viewed as critical for its successful global adoption.
In a document outlining ongoing efforts to align both the modernisation programmes, the Federal Aviation Administration (FAA) said it planned to conduct a 4DT demonstration leveraging previous i4D trials and the second release of the Aeronautical Telecommunication Network (ATN) Baseline 2 DataComm services standard under development by RTCA SC-214 and EUROCAE WG-78.

Status In August 2013, the FAA and SJU reached an agreement affirming their commitment to a time lined convergence path towards the ATN Baseline 2 (ATN B2) DataComm services standard. To accommodate both NextGen and SESAR modernisation roadmaps, a two-step approach was adopted. This comprised first and initial release of the standard to allow for the European implementation of initial 4D trajectory (i4D) operations. This initial release of the ATN B2 DataComm services standard was subsequently finalised and published by RTCA and EUROCAE in the first half of 2014. The second step will allow for the U.S. implementation with a second release of the standard for the full convergence on a common Baseline 2 Aeronautical Telecommunication Network (ATN B2) where the DataComm services standard. Specifically, this final standard will: • Allow for more advanced communications between the aircraft and ground ATM, making it possible to better plan and time slot arrivals; • Allow for more advanced communication regarding the use of satellite-based procedures, such as Required Navigation Performance, thus providing increased flexibility to use more efficient routes; • Allow controllers to convey detailed information to pilots about wind conditions along the path they are scheduled to fly; • Address aircraft spacing.
ATN Baseline 2 DataComm 
In August 2013, the FAA and the SESAR JU reached an agreement affirming their commitment to a time lined convergence path towards the ATN Baseline 2 (ATN B2) DataComm services standard. To accommodate both NextGen and SESAR modernisation roadmaps, a two-step approach was adopted.
This comprised first and initial release of the standard to allow for the European implementation of initial 4D trajectory (i4D) operations. This initial release of the ATN B2 DataComm services standard was subsequently finalised and published by RTCA and EUROCAE in the first half of 2014.
The second step will allow for the US implementation with a second release of the standard for the full convergence on a common Baseline 2 Aeronautical Telecommunication Network (ATN B2) where the DataComm services standard.
Specifically, this final standard will:
• Allow for more advanced communications between the aircraft and ground ATM, making it possible to better plan and time slot arrivals;
• Allow for more advanced communication regarding the use of satellite-based procedures, such as Required Navigation Performance, thus providing increased flexibility to use more efficient routes;
• Allow controllers to convey detailed information to pilots about wind conditions along the path they are scheduled to fly;
• Address aircraft spacing.

“The FAA and SESAR will explore the possibility of performing collaborative validations and demonstration activities in the field that is complementary and building on the initial 4D trajectory (i4D) results towards increased predictability of AMAN and TBFM and TBO services,” stated the partners in the document.
The 4DT demonstration will include the engagement of global avionics industry partners to ensure that the avionics and prototypes are in place to use these standards.
“The purpose of this work is to demonstrate the use of ATN B2 datalink standards for the exchange of 4D trajectories between ground automation systems and aircraft to exercise TBO services including dynamic required navigation performance (DRNP), advance interval management (A-IM) and ATC winds. SESAR members will participate in the 4DT demonstrations as active observers. It is anticipated that the outcomes from this 4DT demonstration will complement future development of i4D trials as well as revisions to the ATN B2 standards.”
The document outlines the current state of progress towards achieving the necessary level of harmonisation and global interoperability between NextGen and SESAR and reflects the current and planned collaboration efforts by the United States and the European Union to harmonise and secure the modernisation of air traffic management not just transatlantically but globally in support of the International Civil Aviation Organisation (ICAO) Global Air Navigation Plan (GANP) and its Aviation System Block Upgrade (ASBU) programme.
Both NextGen and SESAR said they recognised the need to integrate the air and ground parts of their respective ATM systems by addressing efficiency needs of flight trajectories planning and execution and the seamless and timely sharing of accurate information.