Study the Concept of Block Upgrades

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Study the Concept of Block Upgrades

51ST ANNUAL CONFERENCE, Kathmandu, Nepal, 12-16 March 2012

WP No. 89

Study the Concept of Block Upgrades

Presented by TOC


This paper provides an insight to the ICAO Global Harmonisation project that is called Global Aviation System Block Upgrades. It provides details the breakdown of this programme and describes its intended goals. The paper highlights the potential advantages and problems that are likely to be encountered during the implementation of the project.


1.1  During the 50th IFATCA Annual Conference in Amman, Jordan, TOC was given the task of investigating the concept of block upgrades for ATM.

1.2  The topic has been identified through its adoption by ICAO as a prerequisite to ICAOs’ core mission of global harmonisation.

1.3  ICAOs’ Global Air Navigation Plan (GANP) and the Operational Concept (OC) provide the framework of the project.


2.1.1  ICAO was tasked by its ICAO Assembly to increase substantially its efforts as the Assembly estimates expenditure on the various ATM improvements in the near future (10 years) as more than US$120B. Currently there exist at least 2, if not 3 major players in this field that include NextGen, CARATS (Collaborative Actions for Renovation of Air Traffic Systems – Japanese future project in cooperation with SESAR JU) and the SESAR JU. Each of these projects is rapidly changing and developing independently of each other. It was deemed necessary by ICAO to provide a leadership framework to each individual project’s development.

2.1.2  Global Aviation System Block Upgrades (GASBU, or ASBUs) are envisaged to provide “harmonised, manageable and implementable steps forward”.

2.2.1  Block Upgrades have been defined by ICAO as:

  • A clearly defined measurable operational improvement;
  • Accompanying airborne and ground based procedures necessary to make it happen, as well as new separation minimums;
  • The equipment and/ or systems needed in the aircraft and on the ground;
  • An operational approval or certification plan; and
  • A positive business case over a clearly defined time period.

2.2.2  The Block Upgrades describe a method, which allows the ICAO Global Air Navigation Plan (Doc 9750) to be applied to the world of aviation. They are envisaged to synchronise implementation between air and ground systems and between regions through technological roadmaps. The ultimate goal is to have a worldwide seamless aviation system that is created by the demand of safety. ICAO believes that safety must be achieved at a “reasonable” cost.

2.3 What has happened so far, and what is the next timeframe?

2.3.1  Recently, ICAO have been working with both major projects (NextGen and SESAR) to establish a leadership framework that will allow them to identify and combine the global elements from each of their individual regional programs. These will be packaged as ASBUs. These are organised in 5 year incremental phases, starting in 2013 through to 2028. The expectations are that the last Block Upgrade will have long lasting benefits beyond 2028.

2.3.2  ICAO believe that they are changing the focus of an organisation dictating change from the top, to a “bottom-up and pragmatic implementation actions” in the regions. At present there are only 2 major regions investing heavily in this form of development (USA and Europe), and as a result it is TOCs’ opinion that the other regions risk to have a top-down solution imposed on them through other areas’ implementation.

2.3.3  This working method is expected to achieve future global interoperability through the working together by coordination and interaction of ANSPs, regulators, airspace users and manufacturers. This will also increase predictability, not only for each large project, and the various stakeholders, but also those who are expected to fund the upgrades.

2.3.4  For ICAO, the Block Upgrades will enable the development and implementation of the Standards and Recommended Practices (SARPs) to industry and states in a timely and predictable manner.

2.3.5  ICAO are of the opinion that different stakeholders should prepare ATM for the future. The ASBU project should constitute the basis for ATM modernisation. If existing plans are already in existence, ICAO believe that they should be modified to be in line with the objectives outlined in each block upgrade. Experience has shown however, that some of these projects are already more mature than ASBUs, and perhaps some room for negotiation by ICAO should remain. Different regions around the world have varying political priorities, will and finances. The adoption of these plans may not be of interest to some as politicians tend to think in the short term.

2.3.6  ICAO is currently finalising the initial draft packaging of each Block Upgrade into “logical” groupings. They have publicised the packages during the summer of 2011, and have presented their findings during the Global Air Navigation Industry Symposium held between the 21st and 23rd of September 2011. Feedback has been requested from each partner (IFATCA has been listed as a partner) during a 1 years timeframe. The ASBUs will be endorsed during the 12th ICAO ANC in November 2012.

Figure 1 Schedule

2.3.7  ASBUs, in much the same way as SESAR and NextGen, are led by major industrial players and airspace users. There may well be a tendency not to include the smaller, but nonetheless important users of ATM, such as the GA community. These communities would require an inexpensive way to adapt to future requirements, without diminishing their current service levels. In much the same way, some individual states may not have the political will or financial ability to invest in such projects.

2.3.8  Conversely states that currently have little in the way of cutting edge technology could see large leaps in a short space of time, creating increased service levels, but necessitating a large of amount of training for their ATM operators.

2.3.9  IFATCA and IFALPA have made concerted efforts during September 2011’s ICAO Global Air Navigation Industry Symposium (GANIS) to ensure that training is included as an important element of each module.

2.4 ASBU Structure

2.4.1  There are 4 main components of a Block Upgrade:

1) Module

A module will produce a performance benefit supported by procedures, technology, regulations and standards and importantly a business case.

2) Thread

A series of interdependent modules across the Block Upgrade process providing an evolution of significant improvements is known as a thread.

3) Block

A group of modules that when combined provide a significant improvement to current ATM, and allow access to the benefits that arise from its introduction.

4) Performance Improvement Area

Sets of modules in each block are grouped into 4 main areas:

  • Greener Airports
  • Globally Interoperable Systems and Flight Data
  • Optimum Capacity and Flexible Flights
  • Efficient Flight Paths (Trajectory based Ops)

Figure 2 Blocks vs Performance Improvement Areas

2.4.2  Block “0” has been identified as the baseline Block Upgrade. This includes technology that is available currently off the shelf. It includes PBN, CDOs and the flexible use of airspace. Compliance needs and the relevant business cases have already been identified.

2.4.3  Block “1” and “2” represent upgrades to the current baseline. They are expected to include concepts such as “Required Time of Arrival (RTA) for initial 4D trajectories. They will also touch on projects such as automated air/ ground datalinks, enhanced surface awareness, reduced wake turbulence separations and advances in ATFM.

These will be presented as ASBUs where the equipment, procedures and the regulatory approval plan are all included in the business case. These ASBUs are independent of when a state/ region wishes to implement them.

2.4.4  It is of TOCs’ opinion that in order to ensure the harmonisation of global ATM, the omission by ICAO to provide a deadline for the implementation of these ASBUs throughout the globe, is contrary to their initial intention. Once again individualistic industry initiatives will lead before harmonisation and its regulation.

2.5 Block “0”

2.5.1  Block “0” has a total of 15 upgrade packages, these include:

  • Block “0-10” Improved En-Route Profiles;
  • Block “0-30” Information Management;
  • Block “0-35” Improved Flow Performance through Planning based on a Network-Wide View;
  • Block “0-40” Initial Data Link En-Route.

2.5.2  Rather than go into each topic in depth, one has been chosen to give insight.

2.5.3  Block “0-10”

2.5.4  Block “0-10” is intended to improve the requirements of the users operational demands, particularly for those between long haul city pairs. Certain routes around the world are becoming outdated due to their inflexibility. It is expected that the use of technology that has a solid reputation such as PBN, will make improvements possible.

2.5.5  Modern aircraft are equipped with capable navigation systems that are able to cope with flexible routes. Changing upper winds have a direct impact on the efficiency and environmental impact of aircraft. Aircraft operators use sophisticated flight planning systems that can optimise daily routes for their aircraft. Similarly modern ATC systems have improved communication, surveillance and flight data management capabilities.

2.5.6  Combining the above technologies is thought to enable the transition from fixed route structures to flex (or “free flight”) routes. We have seen this before.

2.5.7  Sticking points that have been identified as a hindrance to this concept include:

  • Conventional navigation or minimum use of RNAV;
  • Permanently segregated areas;
  • Rigid allocation of airspace between civil ANSPs and the military;
  • Individual State action (lack of communication between neighbouring States);
  • A fixed route structure.

2.5.8 Block “0-10” is likely to include:

  • Airspace planning; coordination and information on the use of airspace;
  • Flexible Use of Airspace (FUA); sharing of military airspace and other segregated areas;
  • Collaborative Decision Making (CDM) for En-Route Airspace; sharing the knowledge of airspace users requests and availability;
  • Flexible routing (ICAO adopts the term Flex-tracking, otherwise known as free-flight!).

2.5.9 Block “0-10” is seen as a first step towards a more efficient organisation of airspace management. It would, however, require more sophisticated assistance (although through proven technologies, such as PBN) to increase optimisation further.

2.6 Block “1”

2.6.1  Block “1” has a total of 16 upgrade packages, these include:

  • Block “1-30” Improved Information Management;
  • Block “1-31” System Wide Information Management (SWIM);
  • Block “1-40” Initial 4D and Airport;
  • Block “1-81” Remotely Operated Aerodrome Control.

2.6.2  Rather than to go into each topic in depth, one has been chosen to give insight.

2.6.3  Block “1-40”

2.6.4  Block “1-40” can be considered as a step towards the introduction of 4D trajectory based operations exploits the abilities of aircraft FMS to optimise aircraft flight trajectories. Trajectory based operations will increase flight predictability for all ATM stakeholders across regional boundaries. It will enable sequencing and conflict management through separation aids that will minimise radar-vectoring intervention. It will also introduce airport applications to increase safety and reduce ATCO workload.

2.6.5  Currently sequencing and separation, as we know, is based on flight plan data and the ATCOs’ skills. Although efficient, it is of ICAOs’ opinion that it is not accurate enough and increases workload. Individual actions in one sector may have an unknown influence on sectors down route. The transmission of information around airports is currently executed through RT leading to the possibility of errors and increased workload.

2.6.6  It is expected that the introduction of this module will lead to greater use of data link applications in order to sequence and merge traffic at individual waypoints. This is expected to be especially useful when optimising approach sequences using RTA. ICAO will expect the increased use of non-verbal communication to issue complicated route clearances across regional boundaries and for the airport and TMA environment.

2.6.7  This section is further split into 4 elements:

Element 1:

  • Initial 4D Operations (4DTRAD) which will employ;
    • Use of ADS-C;
    • Extensive use of existing, or improved RNAV criteria;
    • Synchronisation of RTA and Controlled Time of Arrival (CTA) with Performance Based Navigation (PBN);
    • Consistent use of CDO;
    • Extension of CPDLC.
  • Trajectory Synchronisation and Monitoring through;
    • Agreement by ATCO and pilot on the (ideal) trajectory of the aircraft;
    • Increased predictability through FMS optimisation and enhanced Flight Data Processing;
    • Early identification of congestion and conflicts.
  • Extensive use of RTA;
    • Not only on approach, but also throughout the cruise;
    • Reduction, or ideally elimination of inbound holding.

Element 2:

  • Data Link Operational Terminal Information Service (D-OTIS);
    • Before and during the flight the crew can request NOTAMs, weather and flight operational information of the departure and destination aerodrome using a single data link service D-OTIS.

Element 3:

  • Departure Clearance (DCL);
    • Use of data link to receive departure clearances (already in use at some airports).

Element 4:

  • Data link Taxi (D-TAXI);
    • Start-up, pushback, routine taxi clearances by CPDLC.

2.7 Block “2”

2.7.1  Block “2” has a total of 8 upgrade packages, these include:

  • Block “2-15” Linked Arrival/ Departure Management (AMAN/DMAN);
  • Block “2-31” Airborne Access to SWIM;
  • Block “2-35” Increased User Involvement in the Dynamic Utilisation of the Network;
  • Block “2-101” New Collision Avoidance System.

2.7.2  Rather than to go into each topic in depth, one has been chosen to give insight.

2.7.3  Block “2-35”

2.7.4  Block “2-35” is intended to develop further the concept of UDPP from an earlier more basic introduction.

2.7.5  This develops on the ideas first encountered in Block “1-35”. UDPP is designed to allow airspace users to intervene more directly in the implementation of flow regulations, in particular when an unplanned event (weather, runway closure etc.) impacts on their schedule. The airlines and other users can work together (interesting concept!), through ATFM to produce a solution that takes into account their commercial priorities which are unknown to ATM.

2.7.6  This Block will also build on SWIM to manage more complex scenarios. It does lead to some interesting relationship issues between commercial competitors. How would a low-cost company ensure fairness with a small, or even large national carrier in flow allocation? The interests of marginal users, such as the GA community would also need to be defended.

2.8 Block “3”

2.8.1  Block “3” has 7 upgrade packages, these include:

  • Block “3-10” Traffic Complexity Management;
  • Block “3-15” Integrated AMAN/ DMAN/ SMAN;
  • Block “3-85” Airborne Separation (ASEP).
  • Block “3-105” Better Operational Decisions through Integrated Weather Information;

2.8.2  Block “3-10” is designed to address the affect on Trajectory Based Operations by external factors such as physical limitations, economic factors and particular events (political or otherwise). The long-term management of these factors through increasing traffic levels is known as “managing complexity”. It could be considered as the R&D section of the ASBU movement.

2.8.3  The use of currently unknown technologies and a more information rich environment will lead to active research where innovative solutions are equally important to the understanding of the unknowns of ATM.

2.8.4  It is expected that most of the ICAO Global ATM Concept will have been put into place before this Block, but not fully. A review of the ASBU concept could take place at this stage in order to address further performance gains.


3.1  ASBUs are a logical stepping stone process towards a future ATM system. They aim to harmonise global energies through this modernisation process and give the process a structure.

3.2  Industry is brought into the process through partnership and clearly defined goals, which importantly includes a business plan for each module.

3.3  As with the SESAR and NextGen projects, it is important for IFATCA to have representation in the decision-making process. This should identify areas that have not been contributed to by IFATCA in both SESAR and NextGen, in order to avoid duplication of efforts. Areas or modules that have not been addressed in these other projects should have IFATCA involvement at ICAO level.

3.4  ASBUs are led by ICAO with cooperation from SESAR JU and NextGen, in order to achieve a “bottom-up” approach to future ATM systems. ICAO member states that do not have the financial means or political will to contribute to this process are likely to have limited options for upgrading their systems.

3.5  As with SESAR JU, ICAOs’ ASBUs are influenced heavily by manufacturers and major airspace users. ICAO should take steps to balance the interests of all stakeholders.

3.6  Additional factors such as controller and pilot training, should also be included in the ASBU process.


It is recommended that:

4.1 This paper is accepted as information paper.


.Address to ATC Global by the Director of the ICAO ANB, 2011.

Aviation System Block Upgrades, The Framework for Harmonisation, 2011.

ICAO Global Air Navigation Plan, 2007.

ICAO ANB Council Briefing, 2011.

Last Update: September 30, 2020  

April 20, 2020   582   Jean-Francois Lepage    2012    

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