Results from Control Task Analysis

The CTA was performed analogous to the consolidated approach described by Naikar et al. (2005). This approach includes two steps which are ‘identification of what needs to be done’ during critical turn-round in terms of work situations and work functions, and ‘identification of what needs to be done’ during critical turn-round in terms of control tasks for each work situation and work function. The contextual activity template (See Figure 16) was used to represent the results of the analysis.

These steps are now described.

Chapter 4: Cognitive Work Analysis

Result I: Identification of Work Situations and Work Functions

The first task of the consolidated CTA was to examine the work segmentation within the critical turn-round path. This was done by using the two-dimensional activity templates during focus group discussions with participating stakeholders in order to identify the valid critical turn-round path that shows the interdependencies between the work functions. Focus group discussions took place during three two-hour sessions with 15 participants consisting of flight crews and responsible SMEs of the relevant round function that are normally at distributed locations during turn-round management.

This approach was useful because the work organized during turn-round takes place at various stages and at various places. However, particular functions need to be performed in a pre-defined sequence in order to adhere to the TOBT that was predicted for the off-block time of the aircraft. While other turn-round activities can be performed in parallel to the critical sequence (see also Chapter 2.5). Standard terminology that is predominantly used for turn-round management during A-CDM was applied to determine work situations. Three flight crews, three controllers, and one airport representative performed the activity analysis of the work function as representatives of the focus group. At an early stage, documented A-CDM turn–round procedures together with procedural descriptions from airlines like Lufthansa, Air France, and British Airways were used, updated from observation and validated using the stakeholders’ experience on critical turn-round management. Descriptions from A-CDM documents contained the A-A-CDM turn-round process with the associated milestones as key monitoring events. Even with small variations that may be present at different airports, all stakeholders could agree on all work functions required for the critical turn-round path. All participating SMEs were asked questions like - ‘Are these all functions occurring during critical turn-round path’, ‘Is the critical turn-round path correct as shown’, ‘Are the responsibilities during critical turn-round correctly depicted’, ‘Are there other locations/potential to better depict the critical turn-round path’.

The critical turn-round path thereby developed includes all processes potentially required; however, depending on the given situation, not all work functions will

Chapter 4: Cognitive Work Analysis

necessarily take place during critical turn-round, e.g. crew change will not always take place or no catering on specific flights.

The decomposition of work situations and work functions during turn-round can be done at different levels of detail and granularity. As it concerns the work situations, a level was chosen that contemplates only the work situations within the critical path that are located at the ramp side of the airport or that directly influence the critical path of turn-round. These processes have to follow the described sequence, but other processes are taking place in parallel in the airport terminal as well as at other locations of the airport. Passenger or cargo handling working situations and functions remained outside of the scope of this project.

As a result of this analysis, the critical turn-round path can be depicted by using the contextual activity template (See Figure 22).

Chapter 4: Cognitive Work Analysis

A-CDM TURN-ROUND PATH

DE-BOARDING TURN-ROUND

SERVICES

BOARDING CLOSING FLIGHT

Park/ Marshalling

Equipment

Flight Documents DAA/ Baggage

Bus/ Stairs/Bridge PAX De-boarding

Special De-board Crew Change I

Aircraft Cleaning Catering

Fuelling A/C Maintenance

Special Service Cabin Sec Check

Crew Change II Special Board

PAX Boarding Baggage Loading

Load sheet Documentation

Last PAX

Closing Doors Remove Equip

Start Up Push Back

FIGURE 22: CONTEXTUAL ACTIVITY REPRESENTATION (NAIKAR, 2005 & SNELLING, 2002)

Chapter 4: Cognitive Work Analysis

The boxes surrounding the work functions indicate all turn-round situations in which the work function can occur. The typical timing for the work function however, is indicated by the bars.

Result II: The Responsibilities within the Critical Turn-round Path

During the analysis of the critical turn-round path, the decisions that are required during these sequenced processes were also identified. Any decision within one of these supporting turn-round processes interacts with other supporting processes, especially during time-critical turn-round management.

During the three focus group meetings between aircrews from the German Regional Carrier, Lufthansa CityLine and turn-round controllers from Lufthansa German Airlines Control Centre, the specific order of the critical events during turn-round were determined and consensus reached on the sequence and responsibility of the processes. As already mentioned, not all turn-round processes take place during each turn-round. However, the proposed path includes all eventual decision making processes that can occur during turn-round. Different airlines might have alternative turn-round process models, but it was argued that the constraints are similar and do not affect the concept. The structure of the focus group discussions was modelled on a series of questions to gradually move the participants from an operational perspective of the turn-round processes to the control tasks that were necessary to perform the functions of these processes. The questions which were used for the discussions were:

• Does the proposed critical path include all turn-round processes as they appear during turn-round in the correct order?

• Who is responsible for each process: a single actor or multiple functions?

• Where is potential for improvement of the critical path?

• Who could contribute in improving the efficiency of each process?

• What are the major challenges and what are the problems associated with these processes?

• What are the control functions for each process?

In a second step, the results were analysed during table-top discussions (Kirwan and Ainsworth, 1992). Overall, it was agreed conclusively that the impact of a

Chapter 4: Cognitive Work Analysis

decision by only a single participant can have significant influence on the outcome of the overall turn-round because the outcome of the decision propagates throughout other processes. Therefore, a way of decision making has to be pursued that is able to coordinate the distributed decisions of participating functions into global decision making where all information is centralized for such control. Many airlines today have started to coordinate decision making in their operation centres. Decisions that cannot be transferred into a control room have to be regarded for the overall TOBT decision.

The discussions were also aimed at finding an agreement on who should be responsible for the work function. Today, distinctive functions are in place to either perform the work function or solve a specific problem during critical turn-round path.

This means that control tasks for most of the work function are shared among actors executing the work functions and those monitoring the critical turn-round path. For instance, during normal turn-round flow the actor who executes the work function is decision maker. However, during unexpected situations, the actor monitoring the turn-round will take over the responsibility of deciding on a new target state.

As a result of the CTA, Figure 23 shows now the turn-round processes with the functions that are responsible for the necessary decisions within the processes.

Chapter 4: Cognitive Work Analysis

Responsibilities within Critical Turn-round Path Airport Operator • Availability of parking position

• Availability of marshaller/ docking system

• Provision of Passenger coach/bridge

• Push-back environment

Airline/ Ground Handler • Provision of pre-arrival information to the air crew

• Ground handling equipment (GPU, stairs, truck...), handling personnel

• Flight documents for next flight sector

• Delivery at Aircraft (luggage)

• Stairs

• Passenger & cabin baggage de-boarding

• Special de-boarding (WCH, UM, Load)

• Crew change

• Aircraft cleaning/ catering/ fuelling

• Special catering/ other services

• Special boarding (WCH, UM, Load)

• Passenger & cabin baggage boarding

• Baggage, cargo, Delivery at Aircraft loading

• Loadsheet, documentation, and last passenger

• Closing all doors

• Removal of equipment & personnel

• Provision of push-back & ground crew for engine start

Air Crew • Crew change (cockpit & cabin)

• Information on aircraft status

• Cabin security check

• Closing passenger doors

Mechanics • Scheduling of turn-round maintenance

FIGURE 23: RESPONSIBILITIES WITHIN THE CRITICAL TURN-ROUND PATH (SNELLING, 2002)

Chapter 4: Cognitive Work Analysis