If You Want To Improve The Safety Of Ground Handling, Look To How It’s Done On An Aircraft Carrier

March 31, 2015
In simple terms, aircraft ground handling should be thought of as a system, but one which needs proper analysis and design instead of analyzing operational risks in an overly simplistic fashion.

The issue of aircraft ground damage is a significant and wide-spread concern among airlines and ground handling companies. And with a disproportionate amount of personnel injuries happening to ground crews when compared to aircrews, most ground handling safety professionals do find themselves dealing with a certain degree of anxiety from time to time.

Undoubtedly, a ground service provider may address one salient part of a safety issue, but do so in a way that misses some other just as important part of the puzzle. And, as we all know from this business, there are many more parts of the puzzle than just two.

As such, what gets accomplished ends up by default to be limited in scope. A main problem with a lot of safety “programs,” therefore, is that they are just that – a program that might address one aspect of the overall issue without addressing all of it.


The good news is that new ways of managing safety that indeed consider it in a thorough, systemic, fashion have been conceived in academia, found their first applications even within the aviation industry, and carry the potential to further improve safety.

Safety scientists such as Sidney Dekker, Erik Hollnagel and Nancy Leveson say that the models of hazard control currently used in the industry are linear-in-nature – that is to say thought for the likes of assembly lines in manufacturing – and not commensurate to the complexities of many modern production systems with human operators in the loop.

These new theories are being conceived exactly for complex and tightly coupled – a more sophisticated word for ‘fast’ – production systems. Aircraft ground handling certainly is complex and certainly is under time constraints.

In simple terms, aircraft ground handling should be thought of as a system.

Only with this approach will the safety of ground handling be managed upon proper system analysis, design and redesign instead of by analysing operational risks in an overly simplistic fashion and doing little bits of work here and there.

A systemic approach to safety is about focussing on what Dekker calls “the web of dynamic, evolving relationships and transactions within complex systems instead of looking at single components in an isolated fashion or at some critical component interactions.”


But how do you use this theoretical approach – and the related safety management tools – in ways that are practical and actually lead to an improved system of aircraft turnarounds?

Luckily enough attempts have already been made at modelling ground handling as a system, albeit as part of a wider effort at modelling the air carrier operations system.

Representatives from the Federal Aviation Administration and U.S. air carriers met several times during 1999-2000 to develop a system engineering model of the generic functions of air carrier operations.

From these meetings, the team developed the Air Carrier Operations System Model (ACOSM), Version 1.0, an FAA document dated 2001 that is downloadable from the Internet.

The ACOSM model structure uses the Integrated Definition Function Model (IDEF0) format which, with its structured language and tool, enhances and clarifies the analysis of critical system interactions and potential system vulnerabilities.

The ACOSM program was meant to be continued by addressing areas that the ACOSM development team identified as requiring further evaluation and definition in a next version of the document (e.g. marshalling) but was never continued.

A particular section (node A2.3) of ACOSM includes a modelling of ground operations in the IDEF0 format. As reported in the ACOSM document, IDEF0 uses boxes and arrows to describe a process. The boxes represent activities conducted within the organization or system and arrows represent objects or information involved in the activities. The arrows are subdivided into four categories:

  • Inputs: items consumed by the activity, e.g. the de-icing fluid used for aircraft de-icing
  • Controls: documentation that guides, regulates, or influences the activity, e.g. rules, regulations, policies, procedures embedded in operations manuals
  • Outputs: items produced by the activity, e.g. the aircraft loaded with its payload
  • Mechanisms: entities used to realize the activity, e.g. ground handling personnel and ground support equipment

In IDEF0 terminology, these are called “ICOMs,” an acronym for
Input, Control, Output and Mechanism.

ICOMs connect to an activity (function) box from different sides of the box:

  • Controls connect at the top.
  • Inputs connect at the left.
  • Outputs connect at the right.
  • Mechanisms connect at the bottom.

Node (activity) A2.3 of the ACOSM model, for example, entitled ‘Perform ground operations’, considers the aircraft turnaround as a system with seven main functions:

  • Manage ground operations.
  • Perform ground handling.
  • Perform cargo handling.
  • Replenish consumables.
  • Perform line services.
  • Perform deicing/anti-icing services.
  • Provide ground operations resources.

All these functions have associated inputs, controls, outputs and mechanism.


The ACOSM model of the aircraft ground handling system is eminently descriptive; as such it cannot alone suffice for proper system modelling, but familiarizing with it is perhaps the way at easiest reach for a ground service provider to start modelling its own ground handling activities as a system.

After the initial familiarization, the only way to go is that the ground handling safety practitioner familiarizes with the new tools for systemic safety management. STAMP (Systems Theoretic Accident Model and Processes) and FRAM (Functional Resonance Analysis Method) are the most popular models and a wealth of literature is available for the ground handling safety practitioner to on these tools. It is beyond the scope of this article to illustrate in detail how these models and tools should be used for a proper system analysis of aircraft ground handling. However, the safety practitioner may refer to Leveson’s book “Engineering a Safer World” and Hollnagel’s book “FRAM: the Functional Resonance Analysis Method.”


If we wanted to speculate as to where a systemic analysis may eventually lead to in terms of mechanisms for safety performance improvement, there is a peculiar type of extremely complex and tightly coupled operations that can be looked at where safety and effectiveness are both outstanding: aircraft carrier operations at sea.

It is very revealing that such a model of high performance includes to a significant extent aircraft handling (although of a different type), because it facilitates the learning of lessons on resilient system performance for those involved in the safety of aircraft ground handling.

One of the analogies we can draw between aircraft ground handling at civil airports and aircraft carrier operations at sea is that they are both characterized by very high personnel turnover.

“Continual rotation creates the potential for confusion and uncertainty, even in relatively standardized military organizations,” reads a 1987 article from the Naval War College Review by researchers at the University of California, Berkeley. “And yet the Navy demonstrably performs very well with a young and largely inexperienced crew, with a ‘management’ staff of officers that turns over half its complement each year, and in a working environment that must rebuild itself from scratch approximately every 18 months.”

The researchers attribute aircraft carrier operations’ remarkable safety and effectiveness to three peculiar traits in their design:

1. Self-design and self-replication

With regard to self-design and self-replication, the researchers note how “operations manuals are full of details of specific tasks at the micro level but rarely discuss integration into the whole. There are other written rules and procedures, from training manuals through standard operating procedures (SOPs), which describe and standardize the process of integration. None of them explain how to make the whole system operate smoothly, let alone at the level of performance that we have observed. It is in the real-world environment of workups and deployment, through the continual training and retraining of officers and crew, that the information needed for safe and efficient operation is developed, transmitted, and maintained. Without that continuity, and without sufficient operational time at sea, both effectiveness and safety would suffer.”

As to how operational factors are maintained and transmitted in the face of rapid turnover, the researchers refer the role of the pool of chief petty officers, many of whom have long service in their specialty and circulate around similar ships in the fleet.

Making a parallel with aircraft ground handling it can be inferred that the role of middle managers and shift supervisors as well as their retention should be emphasized for purposes of bringing to the rotating workforce their shared experience and that an leading an uninterrupted process of on-the-job training and retraining which contribute to make a ground-crew an integrated team, where any new recruit can fast learn to belong to.

2. Authority overlays

With regard to authority overlays, the researchers note the adaptability and flexibility of what is a hierarchically structured military organization in the day-to-day performance of its tasks.

Operations and planning are usually conducted “as if the organization were relatively ‘flat’ and collegial. This contributes greatly to the ability to seek the proper, immediate balance between the drive for safety and reliability and that for combat effectiveness – report the researchers – Even the lowest rating on the deck has not only the authority but the obligation to suspend flight operations immediately, under the proper circumstances, without first clearing it with superiors. Although his judgment may later be reviewed or even criticized, he will not be penalized for being wrong and will often be publicly congratulated if he is right.”

It seems advisable in the aircraft ground handling environment to promote cooperative behaviour, “which tends to minimize the negative effects of jealousy and direct competition” in ways that, however, are not disrespectful of rank and hierarchy – in fact these are “the lubricant that makes the informal processes work.”

3. Redundancy

With regard to redundancy, the researchers report two particular aspects:

  • Internal cross-checks on decisions,
  • fail-safe redundancy in case one management unit should fail or be put out of operation.

As to internal cross-checks on decisions, the researchers report that “seasoned personnel do not ‘listen’ so much as monitor for deviations, reacting almost instantaneously to anything that does not fit their expectations of the correct routine. This constant flow of information about each safety-critical activity, monitored by many different listeners on several different communications nets, is designed specifically to assure that any critical element that is out of place will be discovered or noticed by someone before it causes problems.”

The researchers report as an example a peculiar type of aircraft “handling:” The setting the arresting gear.

“This requires that each incoming aircraft be identified (as to speed and weight), and each of four independent arresting-gear engines be set correctly. At any given time, as many as a dozen people in different parts of the ship may be monitoring the net.”

Because of the built-in redundancies and the personnel’s cross-familiarity with each other's jobs, the researchers note that based on a history of about a million individual settings there had not been a single recorded instance of a reportable error in setting that resulted in the loss of an aircraft.

“Stressing the survivor” and mobilizing organizational “reserves” are efficient fail-safe redundancy mechanisms that are present in naval carrier operations as identified by the researchers.

“Stressing-the-survivor strategies require that each of the units normally operate below capacity so that if one fails or is unavailable, its tasks can be shifted to others without severely overloading them. Redundancy on the bridge is a good example,” report the researchers. “Mobilizing reserves entails the creation of a ‘shadow’ unit able to pick up the task if necessary. It is relatively efficient in terms of both space and personnel but places higher demands on the training and capability of individuals. What the Navy effects, through the combination of generalist officers, high job mobility, constant negotiation, and perpetual training, is a mix that leans heavily on reserve mobilization with some elements of survivor stressing. Most of the officers and a fair proportion of senior enlisted men are familiar with several tasks other than the ones they normally perform and could execute them in an emergency.”

Limiting our systemic safety focus to the positive peculiarities of aircraft handling on naval carriers is revealing.

Learning from such a high-tempo system with an excellent safety performance and interesting similarities with the aircraft ground handling business as well as thinking of safety in a systemic fashion is going to provide change management insights that are far more beneficial to improve our system of aircraft turnarounds.

About The Author: Mario Pierobon holds a Master’s Degree in Air Transport Management from City University London and works in business development and project support at Great Circle Services in Lucerne, Switzerland. Mario regularly writes about aviation safety and his main professional and research interests are in the areas of airside safety.