Air Traffic Management

Towards the end of March, one of Iceland’s volcanoes, the Eyjafjallajokull, started erupting. Apart from lava and flooding from ice and snow sitting on top, it has put a biq quantity of volcanic ash into the air.

This volcanic ash is of danger to aircraft. For more information on volcanic ash and aviation, please go here:

http://www.skybrary.aero/index.php/Volcanic_Ash

Based on the guidelines of the International Civil Aviation Organisation normal air traffic control services cannot be provided to flights in airspaces affected by volcanic ash.

Eurocontrol is coordinating with local Air Navigation Service providers to ensure safety and to mitigate, as much as possible the situation. Here is the press release.

Charts indicating the presence of volcanic ash are regularly updated and presented by met offices and observatory units to aviation.

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This is an article I wrote which has been published on the Hindsight Magazine – A magazine published by EUROCONTROL on ATC Safety. This edition focused on level busts.

In a TMA somewhere in Europe:

Approach: “Tango X-ray Yankee zero five tree, descend to flight level eight zero.”

TXY053: “Roger, descending to flight level eight zero, Tango X-ray Yankee zero five tree.”

After a while as the controller observes the mode C of TXY053 passing FL79 and descending:

Approach: “Tango X-ray Yankee zero five tree confirm maintaining flight level eight zero, traffic in the holding stack at your seven o’clock one thousand feet below your cleared flight level.”

TXY053: “TCAS RA, Tango X-ray Yankee zero five tree.”

…

Around the same time in another TMA not so far away from the first:

Approach: “Victor Zulu Alpha seven seven six, descend to flight level eight zero.”

VZA776: “Roger, descending to flight level eight zero, victor zulu alpha seven seven six.”

After a moment, when the VZA was still passing FL100 in the descent, the controller checks the vertical stack list and notices that the aircraft selected flight level, as input by the pilot is FL 60.

Approach:  ”Victor Zulu Alpha seven seven six, check selected level. Cleared level is flight level eight zero.”

VZA776: “Eeeh, roger, stopping descend at flight level eight zero, Victor Zulu Alpha seven seven six.

There are several reasons why a level bust can happen, and some of the other articles in this issue of Hindsight either talk directly about these, or recount situations where level busts (nearly) happened and then analyse some of the reasons why they did with the aim of learning for the future.

Likewise, there are several ways for us in the aviation community to prevent level busts from happening and (when they happen anyhow) to help us to recover as quickly as possible and avoid a dangerous situation developing.

It is worth mentioning some of the items in our tool kit for prevention and recovery:

The good definition of design and procedures governing the airspace.

The ATC and aircraft operator’s standard operating procedures.

Radio discipline and appropriate phraseology.

Training and awareness on the issue.

Team work, vigilance and situational awareness.

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In the VZA case above, we saw yet another tool in the kit that can assist with the prevention – the display at the controller’s position of the  down-linked selected flight level set on board the aircraft.

This is possible when the air traffic control system in use supports the processing and display of Mode S enhanced surveillance (EHS) and more specifically of the down-link aircraft parameter [DAP] – Selected Flight Level / Altitude (SFL or ALT SEL).  Now, I am not an engineer, so I stop with the technical description while (I think) I am still on top! However, I decided to try and find out whether the display of Mode S EHS SFL actually helps reducing level busts and I discovered the following:

The European Action Plan for the prevention of level busts, dated July 2004 asks air navigation service providers [ANSPs] to consider the introduction of Mode S Selected Altitude display. I found that only two or possibly three European ANSPs have actually introduced this but that all of them reported a significant (in some cases of the order of 25%) decrease in level busts following the implementation..

Also, I found that in general, the controllers working with systems where Mode S SFLis adequately displayed at their working position, are happy with this feature and feel that it is of major benefit to safety.

I then asked IFATCA if they had any concerns about the introduction of an SFL display to controllers and I was told that they had nothing against SFL display but that before implementing such a system an ANSP should study its implications on the system and on the controller in an holistic way. Issues considered should include:

The best way to display the data to controllers.

Prioritisation between warnings (STCA, TCAS, APW, Route deviation, etc. etc.) so as to avoid data overload and any conflict between  alerts, warnings and systems

Legal responsibility issues such as what is the status of the information presented (operational, trial or for information only?) and what are the consequences of using, or not using, such information.

Ensuring that controllers appreciate  that the SFL function displays intent-based information and that there may be circumstances when an aircraft will not fly to its selected level such as when it is being flown manually or when an incorrect altimeter sub scale setting has been used in the cockpit.

In one specific implementation about which I have been informed all the potential technical and operational issues described above seem to have been addressed  The ANSP in question has also sought to clarify that, in terms of legal responsibility, the checking of the SFL display was not mandatory but  that it was encouraged as an additional way to prompt early prevention of possible level busts.  This ANSP also provided detailed briefings to the controllers on the policy and on the tools which were being introduced. As a result Enhanced Mode S was well received and has provided significant safety benefits by reducing the incidence of level busts, which had  previously been identified as one of their major safety risks.

So, if we have good examples of implementations which contribute to significant reductions in the occurrence of level busts, why is this technology not in more widespread use?  Certainly, EHS capability cannot appear on all aircraft straight away and there are bound to be significant costs for an ANSP to install such a system.  Within the scope of this article, I did not choose to investigate further about the reasons behind the lack of implementations. However, what is important to note is that we already have enough operational evidence to show that properly-implemented display of SFL for controllers can significantly reduce level busts.

In conclusion, there are many reasons why level busts can occur. There are equally many means the ATC and the flying communities can adopt to prevent them from happening. Most of these measures are complimentary and the use of one should not exclude the other. Now we have another: the real time display of aircraft selected flight level to the controller.  It is not the panacea for level bust, but can be another significant means of prevention. In my opinion controllers should lobby for its installation in their working environment and ANSPs should endeavour to install it appropriately as quickly as possible. Safety is at stake.

[end of article]

You can find the Hindsight magazine by clicking here

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Three years ago, Eurocontrol set to develop training material to sensiblise air traffic controllers on the risks that can occure during position handovers and to provide suggestions and tools to minimise these risks.

In preparation for the development of this training material, a research study was conducted to identify the factors affecting handovers and takeovers. The document referred to here reports the findings of this research. It includes the following sections:

• A literature review including reports on the study performed by the National Air Traffic Services Ltd. UK (NATS) on handovers and the establishment of best practices based on this study;
• Interviews of Safety Experts which summarises the interviews on handover-related safety hazards conducted with the safety managers of two Air Navigation Services Providers (ANSPs);
• Training Material Review, the existing pedagogic material relative to position handovers in Europe is reviewed and analysed (prior to the Web-based training on factors dealing with handover/takeover produced by EUROCONTROL in 2006);
• Identification of the Main Handover-related Safety Issues’, provides, based on the information collected during the study, a preliminary list of the main handover-related safety issues that should be addressed to improve handover processes and
• Key findings of this preliminary study on handover

It also contains  a number of checklists whcih were in use in different European ANSPs

It can be found here

Enjoy the read.

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I have recently read a very interesting report on the challenges that leading aviation experts identify for the future of ATM, especially in Europe. The conclusion of this study is that even though these experts have identified significant challenges for the future, they still anticipate long term growth for the industry. [since these experts mainly come from the aviation community one can say that at least the experts still believe in their sector, but one can also say that the report may be biased because it is too close to the experts' home. Anyways, I am also too close to be objective...]

Some of the challenging areas they have identified range from the need for more innovation, to defragmentation of airspace, to management of resources to marketing, security environment and ticket pricing. So as you can see it is very broad. Here are some of the broad lines in some of these areas.

Innovation: The challenge is that the rate of innovation in ATM is slower than that of the flight deck for example. Technology ages, regulation and certification cycles are too long…

Safety: Ensuring safety while increasing complexity of the system is another challenge. To this challenge one needs to add another one: of how to conciliate the safety paradigm with the market led economic regulation one [which many times are at perpendicular angles to each other] Yet another challenge in this area will be to maintain the perception of safety [of course this perception needs to be backed up by the real McCoy] in an ever decreasing risk tolerant society.

Environment: A hygienic factor. Society seems to perceive aviation as a major contributor to environmental issues. This may reduce travel demand in the future because of extra taxes and emissions quotas. Here my comment is that better selling of aviation should be done. Where as it is true that toxic emissions and noise are environment issues caused by aviation, it should not be compared to road transport for example. Whereas train travel is seen as an alternative cleaner way of transport to the car – mass transportation,[ noise and emissions] air travel does not. Yet trains pollute as well.

I would say that the emphasis of this challenge should be more on how to selling the industry to society rather than on the reality of the problem itself [I am thinking of the bonus malus schemes in some countries to incite people to buy cleaner cars- but these cleaner cars are still for individualistic use and pollute.]

Defragmentation: A challenge is to defragment airspace and service provision to achieve efficiencies and economies of scales. A barrier to this is country sovereignty but also a lack of clarity of who is in charge of regulation, specification, system construction, certification etc. on a broader scale.

Human in the system: How to bring the human in the system to meet future roles in an intensely automated system? A second issue is that in the transition between current systems and paradigms and the future concepts there is a severe lack of resources which in turn slow down change, innovation and improvement. In a way this is a paradox. We need more people now to define and implement a system which will be more and more automated then….

Scarcity management: The aviation industry is saturated. Resources [fuel, space, etc] are becoming scarce. The industry needs to learn how to efficiently manage scarcity.

Marketing: The industry tries to identify trends in air travel for the future but seems to lack the understanding of the influencing factors t these trends.

Security – The aviation industry needs to deal with this challenge both at the societal side of things but also in the technologies that ensure the running of the system. These systems may become targets of security threats and of sabotage acts which will have implications on safety and efficiency in the future.

Lastly in my list, ticket prices seem to be at their lowest, meaning that the future trend is upwards.

All these challenges will need to be considered both when running day to day business and while conceiving and implementing changes and improvements. The experts thinks there is still hope…

As I wrote before this is an interesting report. Worth a read and a thought.

Click here for the report

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