Go No - Go Decision Point

The decision whether or not to go ahead with implementation needs to be made at a pre-determined point in the life-cycle of a project.

It is usually during the various activities undertaken in the validation phase that it becomes evident whether the proposed Airspace Concept is going to meet the objectives set and therefore can be implemented. 

The decision to go forward with implementation will be based on certain deciding factors, starting with achievement of the goals set for implementation. Other factors could include:

  • whether the ATS route/procedure design meets air traffic and flight operations needs;
  • whether safety and navigation performance requirements have been satisfied;
  • pilot and controller training requirements; and
  • whether changes to ATC systems such as flight plan processing, automation, as well as AIP publications are needed to support the implementation

However, there is more to be considered than just satisfying Safety and Performance Criteria when deciding whether or not to go ahead with Implementation.  The following could be factors that could prevent a ‘go’ decision:

  • A required change to the ATM system, needed to support the implementation, may prove impossible to realise despite careful identification of this enabler and a go-ahead having been given by ATM systems engineers;
  • Dramatic political events which have nothing to do with the Airspace design and which could never have been foreseen when the Traffic Assumptions were chosen, could nullify the entire Airspace Concept. This could occur, for example, if the entire design concept rested on the (traffic) assumption that 80% of the traffic would enter a Terminal Airspace from a single direction and due to unforeseen political events the geographic distribution of traffic changes completely;
  • Unforeseen change by lead operator concerning aircraft equipment upgrades causes the collapse of the Business Case or, for example, the Navigation assumptions.

If the airspace design team is performing as a fully integrated and aware group, it should not be caught out by last minute surprises described in bullets 1 and 3, above.

One thing is certain, however, the possibility of unexpected events is one of the reasons why it is necessary to fix a go/no-go date for implementation.

Pre-Implementation Review

At the Go No-Go decision date, a Pre-Implementation Review is undertaken, the result of which decides whether implementation goes ahead. During the Pre-Implementation Review, the Airspace design project’s progress is measured against the implementation criteria selected during the planning stage.

Examples of Criteria which an Airspace Design Team may have selected to determine whether to go ahead with implementation or not include:-

  • Collapse of the main assumptions;
  • Critical Enablers become void;
  • Emergence of a project-critical constraint;
  • Performance/Safety Criteria are not satisfied during or by the Validation or Safety Assessment process;
  • No regulatory approval;

‘No-Go’ Decision

Although it can be very discouraging to be confronted with a ‘no-go’ decision, it is essential that attempts should not be made to ‘produce’ a quick-fix’ or work-around’ so that implementation takes place at any cost. However difficult it might be not to proceed with implementation, a ‘no-go’ decision should be respected.

The route to be followed after a ‘no-go’ decision depends upon the reason for which the no-go decision was reached. In extreme cases, it may be necessary to scrap an entire project and return to the planning stage. In others, it might be appropriate to return to the selection of Assumptions, Constraints and Enablers. And it is also possible, that a new Validation exercises will have to be developed, or a new Safety Assessment completed.  What-ever the route, the work needs to be re-organised and re-planned.

‘Go’ Decision – Plan Implementation

If, on the other hand, all the implementation criteria are satisfied the Airspace design team needs to plan for implementation – not only as regards their ‘own’ airspace and ANSP but in co-operation with any affected parties which may include ANSPs in an adjacent State.   Amongst items to be covered are ATC system integration and Awareness and Training material.

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