De la Prehistoria al Imperio Romano

Error! Reference source not found. provides flight crews’ assessment of possible failure causes expressed in three components aims, resources, and abilities. Even though it was questioned whether it is possible for flight crews to identify or understand such failure causes objectively (See Chapter 5.2), the usefulness of the results for providing a meaningful comparison between different turn-round failures is likely for the following reason: flight crews have operational experience from a home base airport with which they are familiar. Since all participating flight crews fly for airlines having a large network operation, flight crews can easily compare turn-round services from other airports with their home base airport. Error! Reference source not found. therefore compares the different ratings of the three components aims, resources, and abilities as possible failure causes like reported by the flight crews:

FIGURE 26: POSSIBLE FAILURE CAUSES DURING TURN-ROUND EVENTS

During all situations, except ATC information sharing, insufficient resources were seen as responsible for delays of the proposed turn-round situations with highest values assigned to ramp and terminal service processes. Remarkably high values were also assigned to insufficient abilities. The only non-cooperative situation from flight

2.59

Insufficient Participants' Competencies Insufficient Resources Competing Aims

Chapter 5: Flight Crew Survey on Turn-Round Constraints

crews’ perspective and analogous to Ferber’s cooperation model is the assignment of parking stands.

Flight crews were also asked to report about possible other reasons for turn-round failures (Figure 27):

FIGURE 27: OTHER REASONS FOR TURN-ROUND PROBLEMS

The main reason reported refers to the turn-round time that is too short: If this is the case, there is not sufficient time to compensate any process delay. The second reported was the responsibility for decision making that was reported to be inappropriately shared. Further reasons mentioned were reason related to important information that is hidden among an overload of information provided to the flight crews, and also the inappropriate communication facilities that do not allow addressing concerns during turn-round.

Flight crews also had the possibility to mention other causes of problems in free text. Although some reported results correspond to the causes proposed in the questionnaire, they were stated explicitly using the free text option. Table 7 presents these responses.

1 1.5 2 2.5 3 3.5 4

Turn-Round Time too short Information Overload Inappropriate Sharing of Responsibility Inappropriate Communication Facilities

Chapter 5: Flight Crew Survey on Turn-Round Constraints

TABLE 7: POSSIBLE CAUSES FOR TURN-ROUND FAILURES

Possible Causes No of Reports

Not sufficient ground personnel 7

Motivation and competence of ground personnel 6

Lack of competent ramp agent 5

No situational awareness of airport partners and actors 3

Too many different decision makers 3

Not enough training of ground personnel 2

No clear sharing of responsibilities 1

No or inappropriate use of communication devices 1

Bad coordination of ground handling processes 1

Unrealistic scheduling of processes 1

Decisions outside of captain's assessment 1

Inappropriate delay code assignment falsifies real causes 1

Too much time pressure during turn-round 1

Information sharing with service providers 1

A further question to be answered aimed at identifying the flight crews’ perspective to decision making during turn-round was:

“Do you think it would be an advantage if the flight crew were more involved in decision making on operational issues during turn-round?”

From 93 flight crews who answered this question, 65 answered with “Yes”

(representing 70 % of all valid answers) giving the following reasons (n = 28 or 30.1

% were against more flight crew involvement) listed below in Table 8.

TABLE 8: REASONS FOR COCKPITS’ INVOLVEMENT IN DECISION MAKING

Reasons in Favour of more Flight Crew Involvement No of Reports

Situational Awareness best placed at aircraft 34

Earlier detection of problems and so earlier solutions possible 5

More information in hand 5

Crew has final responsibility for the flight 5

Dispatch too far away from action level 3

Fastest possible response + solution to arising problems 3

Better evaluation of possibilities in hand and time required 2

Captain should be place where information gather 2

Last minute problems only present at the cockpit 2

Often other decision makers do not have sufficient time in hand 2

Less mental stress through avoidance of 'surprises' 1

More experiences with similar situations 1

More flexibility 1

Dispatch not always competent enough 1

For specific situations, e.g. aircraft change, technical 1

Only, if decision making is defacto made by flight crew 1

Better teamwork instead of debating with dispatch 1

Only for decisions where judgement is better possible from cockpit 1

Chapter 5: Flight Crew Survey on Turn-Round Constraints

Flight crews who are against more involvement in decision making argue (Table 9):

TABLE 9: REASONS AGAINST COCKPITS’ INVOLVEMENT IN DECISION MAKING

Reasons against Cockpits’ Involvement No of Reports

Crew has other tasks 4

Work load already too high 6

Against Flight Safety 2

Not sufficient Situational Awareness at Aircraft 12

Only shifting of responsibilities to cockpit 1

Not enough time 3

Not necessary, if appropriate processes are in place 2

If necessary, information can be forwarded 1

Too many different opinions 1

5.5 Concluding Aspects

Having identified the constraints framing A-CDM and turn-round management, the survey as designed to find the situations where these constraints occur during turn-round operation and result in service failures, process delays, and TOBT inaccuracy. Given the rising number of stakeholders and participants involved in even for a single turn-round only, it was assumed that a number of turn-round process failures could result from non-cooperative behaviour among participants.

Therefore, an investigation was pursued that utilises qualitative data of aircrews because they are normally not blamed for failures during turn-round. However, seen from the perspective of the airline flight crews, the overall collaboration during day-to-day turn-round operation was perceived as cooperative. The only example that was captured as being non-cooperative is the assignment of parking stands (Chapter 5.4), if following the theoretical model of cooperation as proposed by Ferber (1995).

According to Ferber (1995) a cooperative situation is the prerequisite for successful collaboration and cooperation depends on aims, abilities and resources (see Chapter 3.2). In the context of turn-round operation, information was viewed as one of the resources that have to be provided to the TOBT decision maker. However, another result from the survey reveals that turn-round operation is limited by failures to share timely and relevant information with the airline flight crews, and also by not using the information that is provided by the flight crews. At the same time, the study was also used to identify which information is finally required to predict turn-round process duration and which can so be used for calculating TOBT predictions. Which information is already available that would allow making earlier and more accurate

Chapter 5: Flight Crew Survey on Turn-Round Constraints

TOBT updates was also analysed. These findings were later used to design the experiments (see Chapter 7).

The initial assumption that timely provision of information about turn-round service problems to aircrews could be beneficial in avoiding a turn-round process delay was not provable. However, the effects of information sharing failures on TOBT predictability could be demonstrated by comparing the delay caused by turn-round process failures with the overall delay of the turn-turn-round: the relation between the turn-round delay and the process delay showed significantly higher values for the turn-round delays. This result was compared with the inaccuracy swing effect (bullwhip effect) as an analogy from the production industry where the network of service providers can oscillate in very large swings - if the process takes place within the critical path of turn-round events.

Chapter 6: Field Observation During A-CDM Turn-Round

6 FIEL D OBSE RVATION DURI NG A-CDM TURN-ROUND 6.1 Aims and Objectives of the Analysis

The aim of this study was to develop a better understanding of how operators monitor the complex, dynamic aircraft turn-round operation and to identify the influences of the monitoring strategies on TOBT prediction accuracy. It outlines the currently used practice of turn-round monitoring of flights preferably having only minimum turn-round time available for the turn-round process. The analysis is expanded to consider:

• aspects of situational awareness required for turn-round management;

• problems identified in achieving an accurate and reliable TOBT;

• cognitive aspects that have influence on the turn-round process and TOBT prediction; and

• current modes used for information sharing among airport partners.

The underlying aim was also to identify whether TOBT predictions are influenced by the current approach to turn-round monitoring and whether TOBT predictions can be improved so that less updates are required and deviations from first assigned TOBT remain small.

6.2 Method

While some turn-round situations can be pre-planned, decision makers will always be faced with unanticipated situations resulting from unknown variables in the environment or technological capabilities. These situations can affect time estimates of turn-round processes resulting in an inaccurate TOBT prediction. However, since ATC uses the TOBT as a reference for building the pre-departure sequence, deviations from TOBT may interfere with the stability of the departure sequence. To counterbalance this unreliability, ATC has to build in extra buffers between TSAT and Target Take-Off Time (TTOT) with the consequence of poor TTOT prediction for the airlines and the overall network.

Therefore, field observations were conducted to capture how airline operators monitor the complex, dynamic turn-round process of aircraft, passengers, and cargo in

Chapter 6: Field Observation During A-CDM Turn-Round

normal operation in situ for a total of 122 hours. The observation time was different between airlines a, b,c,d, and e (a = 82h, b = 14h, c = 10h, d = 8h, e = 8h) because of the large differences among the airlines in managing the turn-round process.

Observations took place in five different operation centres from Lufthansa German Airlines, British Airways, Air France, KLM, and Brussels Airlines. Focus was applied placed on monitoring turn-rounds with only minimum turn-round time available.

According to Su et al (2005), visualisation, situational awareness, proactive/reactive monitoring, and interactive capabilities are the four core elements necessary for effective human monitoring of complex systems. If one of these elements is missing, decision making will always involve handling uncertainties. The control room observations at the airline operation centres were carried out with focus on these core elements while keeping in mind that decision making is never fully predictable because of the imponderability from environment or operators intentions.

Turn-round operation is getting increasingly complex, because of interdependencies between third party ground handling service providers, the number of participating parties for each turn-round, size and dimension of airports, and the decreasing time available for each individual turn-round. How human operators monitor the quality of these networks not only has a great impact on the efficiency of the turn-round operation, but also flight punctuality and passenger satisfaction depend highly on a reliable turn-round process.

The method used for analysis evolved from this given situation. Observations (preferably with minimal interruption to activities) were carried out with the following questions as key drivers:

• What are the tasks of the turn-round controller and what does the practice of TOBT assignment look like?

• What are the current modes used for monitoring the turn-round?

• What are the monitoring and facilitating activities used by the turn-round controllers?

• What technological configurations are available for turn-round monitoring?

• What cognitive challenges are inherent in the turn-round monitoring task?

• What strategies do turn-round controllers use?

Chapter 6: Field Observation During A-CDM Turn-Round

To organize the results, a model analogous to that of Vicente (1999) was applied that is able to capture the cognitive, monitoring, and the facilitating activities of the controller that he applies during turn-round. A detailed description of his model can be found in Chapter 6.3.8 that also provides the reason for its relevance for turn-round monitoring. High importance was assigned to the findings and therefore detailed results from control room observations are given in Chapter 6.3. They were also used as basis for designing the experiments.

6.3 Results