Airport Collaborative Decision Making (A-CDM) Concept Elements: Setting Milestones

The Concept Elements of European Airport CDM

This is part 2 of a 6-part series on European Airport Collaborative Decision Making, in which we explore the first 4 out of 6 concept elements that constitute the implementation of an A-CDM project. Part 1 provided an introduction to the history and the scope of collaborative decision making initiatives on the Old Continent.

In this episode, we’ll take a closer look at the project implementation steps every European airport that takes itself and Collaborative Decision Making seriously, implements according to the Eurocontrol A-CDM Implementation Manual , before being declared as an A-CDM airport. I’m deliberately using the word ‘declared’ here, as there is no real certification process involved; sharing airport data by means of departure planning information messages suffices for Eurocontrol to have your airport designator code added to the slowly expanding list of A-CDM practitioners.

Walk in the Park?

Now, one may be tempted to believe that this feat is easily achieved within a couple of months. And indeed, technically speaking, setting up the DPI communications link after agreeing on a data exchange protocol may well lie within this range,  but for your data to be of added value for the Network Manager and his Enhanced Tactical Flow Management System , one better comes to terms with the defined 6 concept elements…

Airport CDM

First Things First: MoU

But before getting started, better to have all noses pointing in the same direction: you start off by signing a Memorandum of Understanding in which every contributing stakeholder commits himself to not only talk the talk, but above all to walk the walk with regards to development and training efforts, costs and agreed timelines. Some prefer to sign this document in the close confines of the boardroom, but others, like Stockholm Arlanda airport, where a Brussels Airport delegation was invited for a brief ‘lessons learnt’ showcase, arrange a charming little ceremony for the airport community to spread the word of exciting times ahead.

Information Sharing: ACISP

I’ve done a lot of reading on A-CDM on the internet the past couple of years, and my impression is that many out there believe that the installment of an A-CDM Communication & Information System Platform (ACISP) is the last step on the way to collaborative decision making.  I have to disappoint those who think it’s the last step; it’s the first, rather. Moreover, the investment aspect not taking into consideration, it may have proven to be the easiest hurdle on the way to implementation for many airports when looking back.

Several options for the airport here: you build extra functionality into legacy systems that already managed to exchange operational data, or plug in a tool or protocol to have legacy systems “talk” to each other, or buy one of the solutions offered by the industry. And believe me, there are MANY providers out there eagerly looking out for opportunities to show off impressive software solutions that will cater to your needs.

So, after perhaps a long and tiresome selection round, you, or rather your software provider, will announce to the world that System X or Suite Y has been successfully deployed at your airport. Wonderful. One more detail, though: let’s now put every stakeholder in charge to fill this data base, and let them share their data with the airport community so that it can be duly interpreted for operational purposes at the airport, and beyond.

I hope you forgive my sarcasm here…

The Milestone Approach + VTT = Collaborative Pre-Departure Sequence

The aim of A-CDM: Raise common situational awareness in order to enhance predictability in airport operations. Keeping track of inbound flights and the progress of the turn-around process once docked at the gate. For that purpose, Eurocontrol prescribes the deployment of 16milestones, covering a substantial part of a flight’s trajectory(one of aviation’s latest buzz words) into an airport and back out of it. Time stamps are to be made available by the stakeholders who have confirmed to be the respective source of the data reporting over each milestone.

A-CDM

Key milestones are:

• Target off-blocks time (known to you as TOBT, as from now on), which advises the airport community on the departure readiness of an aircraft. It can originate from various sources, depending on the stage of the turn-around process and can range from a calculated airport operator value based on estimated arrival and minimum turn-around time (MTT), or manually updated by the airline (AO) or the handling agent (GH) to reflect the operational situation.

• Target start-up approval time(TSAT), ‘in reply’ to TOBT, which of course considers the TOBT, takes Air Traffic Flow & Capacity Management (ATFCM) restrictions into account and establishes the airport’s pre-departure sequence . TSAT management is mostly an exclusivity of the Air Navigation Service Provider (ANSP).

If not already the case, by the end of this episode you’ve figured out that we Europeans are in love with acronyms…

This is the core of the A-CDM process. Well mastered, played by the book, strictly adhering to procedures, it’s a transparent and waterproof procedure that allows ATFCM to optimize air traffic capacity, by taking ground movements and turn-around constraints into account.

However, pre-departure sequencing requires another data element to be put in place beforehand: the variable taxi time (VTT). This time interval sort of bridges the ‘gap’ between whatever is happening at the aircraft stand and what is bound to happen in the air (and vice versa), and is produced by a tool called the D-MAN, to make sure that the throughput at the runway runs optimal. For that purpose, the D-MAN looks at fleet mix, instrument departure procedures, runway configuration, aircraft taxi patterns… Meaning: reduced taxi times up to and reduced queuing at the runway holding point. Also meaning: trying to keep an aircraft as long as possible at the gate, but I’ll come back later on this issue

VTT’s are also calculated for inbound taxi rolls in pretty much the same way, thus highly ameliorating the quality of the estimated in-blocks time.

Up to the fourth concept element, and in comes the tricky part… but all about this in the next episode. Do you have questions or comments? Leave them below.

This article is part 2 in a series of 6 on European Airport Collaborative Decision Making.

Additional Resources European Airport CDMPhoto credit: Y. Ferriere