FISCAL IMPACT OF GROUND OPERATION INCIDENT INVOLVING
AIRCRAFT

Tan Poh Tiong, Sherman

AE6200 – Individual Project (Aircraft IEng)

27 April 2014

SUMMARY
For the year 2010 to 2012, ground operation incident involving aircraft has cost the
United Kingdom (UK) aviation industry an estimate of US$ 20 Million. It is estimated that each incident involving traditional aircraft (mainly metallic structure) would cost the Aircraft Operation (AO) close to US$ 1 Million in expenditure and if the aircraft is assumed to be of high composite ratio, the cost of each incident increase by 50% to
US$ 1.5 Million. Do note that this cost does not include damage to the facilities, equipment, or vehicles. Which mean the overall cost could be higher than the estimate. If damage were assumed in all ground operation incident report, the estimated cost would increase 3.5 times. And with high composite ratio aircraft becoming the norm, the cost could spiral upward in excess of more than 5 times. Thus, it is important these ground operation incidents are reduced.
Ground operation incident, occurs primarily due to human errors. Possible common reasons include insufficient training, complacency and environmental factors. There are also no detailed legislations in place to regulate the industry, unlike Maintenance
Repair Overhaul (MRO) organisations, which is governed by the Civil Aviation
Authority (CAA) of UK.
Since human errors aren’t a new problem, many researches have been conducted in the past. There are systems developed to address the issue of human error.
However, these systems, namely Safety Management System (SMS) and Fatigue
Risk Management System (FRMS) are not mandatory in ground operation.
In the era of electronics and computing, the industry should harness it capabilities to form a safety net.
Thus, in this report, 2 main recommendations are given in attempt to reduce ground operation incident. Firstly, ground operation companies and personnel are to be regulated, to improve the safety aspect and outline the legal responsibilities.
Secondly, introducing technologies into the industry, to aid the reduction of human errors. 27 April 2014

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TABLE OF CONTENTS
1
INTRODUCTION ................................................................................................... 1 2 METHOD ............................................................................................................... 2 2.1 GROUND OPERATION INCIDENT TREND ....................................................... 2 2.1.1 Recent Years Ground Operation Incident Data Acquisition.................. 2 2.1.2 Recent Years Ground Operation Incident Data Analysis...................... 2 2.2 PAST GROUND OPERATION INCIDENT RESEARCH ..................................... 4 2.3 COST ANALYSIS OF DAMAGE SUSTAINED ON TRADITIONAL AIRCRAFT . 4 2.4 IMPACT DAMAGE ON AIRCRAFT MATERIALS ............................................... 4 2.5 COST ANALYSIS OF DAMAGE SUSTAINED IF IT IS A HIGH RATIO
COMPOSITE AIRCRAFT ............................................................................................. 4 2.6 CURRENT LEGISLATION ON GROUND OPERATION SAFETY...................... 5 2.7 CURRENT TECHNOLOGIES AIDING INCIDENT REDUCTION ....................... 5

3 RESULTS .............................................................................................................. 6 3.1 GROUND OPERATION INCIDENT TREND ....................................................... 6 3.1.1 Recent Years Ground Operation Incident Data Acquisition.................. 6 3.1.2 Recent Years Ground Operation Incident Data Analysis...................... 7 3.2 PAST GROUND OPERATION INCIDENT RESEARCH ................................... 11 3.3 COST ANALYSIS OF DAMAGE SUSTAINED ON TRADITIONAL AIRCRAFT12 3.4 IMPACT DAMAGE ON AIRCRAFT MATERIALS ............................................. 16 3.5 COST ANALYSIS OF DAMAGE SUSTAINED IF IT IS A HIGH RATIO
COMPOSITE AIRCRAFT ........................................................................................... 19 3.6 CURRENT LEGISLATION ON GROUND OPERATION SAFETY.................... 26 3.7 CURRENT TECHNOLOGIES AIDING INCIDENT REDUCTION ..................... 27

4 LIMITATION ......................................................................................................... 30 4.1 COST FIGURES ............................................................................................... 30

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4.2 DATA SELECTION ........................................................................................... 30

5 DISCUSSION....................................................................................................... 31 5.1 FISCAL IMPACT ............................................................................................... 31 5.2 GROUND OPERATION TREND ....................................................................... 31 5.3 COMPOSITE MATERIAL DAMAGE ................................................................. 32 5.4 SOLUTIONS...................................................................................................... 33 5.4.1 Human Factor Program ...................................................................... 33 5.4.2 Regulating Industry ............................................................................. 34 5.4.3 Introducing Technology to the Industry............................................... 34

6 CONCLUSION ..................................................................................................... 35 7 RECOMMENDATIONS........................................................................................ 36 7.1 REGULATING THE GROUND OPERATION INDUSTRY ................................ 36 7.2 INTRODUCING TECHNOLOGIES TO THE INDUSTRY .................................. 36

ABBREVIATIONS AND ACRONYMS ....................................................................... 38 8 REFERENCES .................................................................................................... 40 9 BIBLIOGRAPHY .................................................................................................. 41 (Word Count – 7274 not including table of contents and headings and appendices)

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1 INTRODUCTION
Ground operation incident have been an industry wide issue since the beginning of flight and the fiscal impact on the industry worldwide is estimated to be more than
US$10 billion annually. The primary reason why incidents occur is due to subconscious human errors. However, human are involved in all aspect of ground operation, making it difficult to eliminate. There is also a saying “To err is human”, so human errors are just human nature.
Much research has been conducted into the cause of human errors in the industry.
And all research points out that when there is human working on something, errors are bound to happen sooner or later. The researches also categorise the errors and came out with methods to help reduce the errors. However, the ground is a highly dynamic and repetitive environment, the trend of incident may tend to shift, rendering past methods used to reduce incident useless.
With the advancement in material science, newer generation aircraft are shifting from metals to Fibre Reinforce Plastic composite (FRP). FRP composite has a high strength to weight ratio, as it combine properties of 2 or more material in 2 phases, the fibre and matrix. The fibre would provide the tensile strength while the matrix would provide the shear strength and transfer the load to the fibre.
Thus, FRP composite makes it attractive to be used in aircraft, as it would reduce the aircraft weight substantially, which in turn reduces operational cost (fuel burn during flight). The FRP composite content of current generation of aircrafts is 10 times more than aircraft from 25 years ago. This makes it important to understand the fiscal impact of traditional aircraft damage and composite aircraft damage.
The aim of this project is to come up with 2 recommendations to help in the reduction of ground operation incidents involving aircraft.
In order to attain the aim, there are 4 objectives. The objectives are;
1. Identify and analyse the current ground incident trend
2. Identify and analyse the fiscal impact of ground operation incident between traditional and high ratio composite aircraft
3. Identify any current legislation on ground operation safety
4. Identify any current technologies aiding the reduction of ground operation incident
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2 METHOD
2.1

GROUND OPERATION INCIDENT TREND

2.1.1 Recent Years Ground Operation Incident Data Acquisition
To understand the current problem associated with ground operation incident involving aircraft, statistical data has to be acquired. The type of statistical data required will be annual total aircraft movement, annual total ground operation incident; involving aircraft and no involving aircraft, and details of incident report involving aircraft.
It is decided that 3 years of statistical data will be sufficient to understand the current trend of ground operation incidents. Thus, request for statistical data for year 2011 to
2013 were made to multiple aviation authority and organisations via email, and these organisations includes, Civil Aviation Authority of United Kingdom (CAA),
International Civil Aviation Organisation (ICAO), International Air Transport
Association (IATA), and Airport Council International (ACI).
2.1.2 Recent Years Ground Operation Incident Data Analysis
The received data will be analysed and classified into different categories, which are, types of human failures, party at fault, phase of incident, and type of damage. This will provide an in-depth view of the trend of ground operation incident.
2.1.2.1 Types of Human Failures
Based on current literature on aviation human factors, there are 2 types of human failures. They are human errors and violations.
Human errors can be further broken down into skill-based errors and mistakes. Skillbased errors include slips and lapses. Slips occur due to attention deficit. While lapses occur due to memory deficit.
Mistakes are decision-making failures and can be split into 2 types, namely rulebased mistakes and knowledge-based mistakes. Rule-based mistakes occur when the human (operator) is unfamiliar with the situation, and attempt to solve the problem with a set of memorised rules, which could be wrong or inappropriate. While knowledge-based mistakes occur when the human (operator) identify the current

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situation does not match any of the memorised rules, and attempt to solve the problem with limited knowledge of the situation.
Violations are intentional failures that occurs when the human (operator) deliberately break the rules, which can be due to routine, situational, or exceptional cases.
This will provide a statistical view on the reason behind the incident and is particularly important to understand what caused the incident and why it happens.
2.1.2.2 Party at Fault
Based on the data, the party at fault will be identified and grossly categorised into 4 main groups of personnel. They are the ground operation team, pilots, 3rd party and management. The reason for these categories is based on the personnel’s area of work on or around the aircraft. However, ground operation team includes a wide range of personnel, it will be further broken down into their occupation, to provide a holistic view on the ground operation crew.
This will provide a statistical view on the major offender and is particularly important to understand who is responsible in causing the incident.
2.1.2.3 Phase of Incident
Based on the data, the phase of incident will be identified and categorised into 3 phases, which are parked, parking/push back and taxi. This will provide a statistical view on the incident phase and is particularly important to understand when did the incident happen.
2.1.2.4 Type of Damage
Based on the data, the type of damage identified will be based on the area of impact, and major damage that will cause the aircraft to be removed from service for immediate repair, minor damages which the repair can be carried out in line maintenance; or deferred to be carried out at the next heavy maintenance check, contact but no damage, or near contact. This will provide a platform to perform cost analysis on damage incurred on the aircraft.

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2.2

PAST GROUND OPERATION INCIDENT RESEARCH

Literature researches are conducted to find any information that the data acquired could not provide.

2.3

COST ANALYSIS OF DAMAGE SUSTAINED ON TRADITIONAL AIRCRAFT

With the data from Section 2.1.2.4, cost analysis will be carried out to understand the cost incurred by the Aircraft Operator (AO) following a ground operation incident involving aircraft.
The request for cost of repair or replacement for certain parts of the aircraft that is most prone to damage during ground operation is carried out by means of emailing
AO (which includes Singapore Airline (SIA), British Airways (BA), and Cathay Pacific
Airways), Maintenance Repair Overhaul (MRO) Organisation (which includes
Singapore Technology Aerospace Engineering Ltd (STaero), SIA Engineering
Company (SIAEC) and Hong Kong Aircraft Engineering Company Ltd Singapore
(SHEACO)), and conducting literature research on the topic.

2.4

IMPACT DAMAGE ON AIRCRAFT MATERIALS

Literature researches will be conducted on the topic to understand the result of impact damage to different material used in an aircraft. The most common material used in aircraft are metals e.g. aluminium and titanium. However, with the advancement in material technologies, newer generations aircraft are shifting to the usage of composite material e.g. Carbon Fibre Reinforced Plastic (CFRP), Glass
Fibre Reinforced Plastic (GFRP) and Aramid Fibre Reinforced Plastic (AFRP). Thus, the research will be focusing more on composite material.

2.5

COST ANALYSIS OF DAMAGE SUSTAINED IF IT IS A HIGH RATIO
COMPOSITE AIRCRAFT

In order to project the possible cost of repair on composite aircraft parts, the data from Section 2.3 will be interpolated to show the possible cost difference between both types of aircraft.

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The interpolation should be carried out base on two multiplying factors. They are the cost difference multiplier between the 2 type of material, and the cost difference multiplier of production cost between traditional and high ratio composite aircraft.
However, composite materials typically have higher specific strength, which means less material is used to produce the parts with the same strength. A third multiplying factor is required to correct for weight reduction of the parts.
The multiplying factor of cost difference between the types of materials is basically the ratio of cost of 2 different types of materials. The purpose is to correct for the material cost difference.
Next, the multiplying factor of cost difference in production cost between traditional and high ratio composite aircraft is the ratio of time required to produce 1 similar part in material A, to material B. The purpose is to correct for the cost of production between the 2 materials.
Lastly, the specific strength multiplier will be the ratio of the specific strength between both materials. The specific strength of a material is the material’s strength divided by its density. In this instance, the young’s modulus is chosen to be the material’s strength for the calculation of the specific strength. The purpose is to correct for the amount of material used in the production of the parts.
The interpolated cost will then be obtained by multiplying the cost obtained from
Section 2.3 with the weight reduction multiplier, the material cost multiplier and production cost multiplier.

2.6

CURRENT LEGISLATION ON GROUND OPERATION SAFETY

Literature researches are carried out to find any current legislation related to ground operation safety.
2.7

CURRENT TECHNOLOGIES AIDING INCIDENT REDUCTION

Literature researches are carried out to find any current technologies that aid in the reduction of ground operation incident

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3 RESULTS
3.1

GROUND OPERATION INCIDENT TREND

3.1.1 Recent Years Ground Operation Incident Data Acquisition
Although CAA, ICAO, IATA, and ACI were contacted, only CAA responded to the request. Unfortunately, CAA was unable to provide 2013 data, as the year has not ended when this project commenced. Thus, data from 2010 to 2012 was requested instead. The data provided by CAA came in form of Microsoft Excel format with the date of incident, aircraft made and model involved, location of incident and a headline or narrative text of the incident report. These data are based on the CAA Mandatory
Occurrence Reporting (MOR) scheme, CAP 382.
From Figure 1, there was a sharp decline in aircraft movement in 2012, this was probably due to the United Kingdom economic crisis in 2012, where customers reduce the need for recreational travel. However, even as aircraft movement plummeted in 2012, and from Figure 2, it can be seen that ground operation incidents continues to rise steadily throughout those years.

Aircra& Movement in Thousands 2960 2940

Aircra. Movement in Thousands

2920 2900 2880 2010

2011

2012

Figure 1 2010 to 2012 Aircraft Movement in United Kingdom

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600 500 400 300 200 100 0

Involving Aircra. Not involving Aircra. 2010

2011

2012

Figure 2 2010 to 2012 Ground Operation Incidents

3.1.2 Recent Years Ground Operation Incident Data Analysis
Using the description in the headline or narrative text from CAA data, the types of human failures, party at fault, phase of incident, and types of damage are determined judgementally.
3.1.2.1 Type of Human Failures
Data from CAA was analysed and grouped accordingly based on the human failure definition in Section 2.1.2.1, as shown in Figure 3. It can be noted that the most common type of human failures are mistakes. However, there are certain reports that were unclear, and as a result, the type of failure is classified as “unable to determine”. 27 April 2014

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Unable to determine ViolaEons

100% 80% 60%

Mistakes

40%

Lapses

20% 0% 2010

2011

2012

Slips

Figure 3 2010 to 2012 Human Failure Trend
3.1.2.2 Party at Fault
Similarly, data from CAA was analysed and grouped accordingly based on Section
2.1.2.2 and shown in Figure 4 2010 to 2012 Party at Fault Trend. To provide a clearer view of the situation, the ground operation team is further broken down into their job role as shown in Figure 5. It can be noted, the highest offender are the drivers. However, driver could also include ground crew with airfield driving license.

Management

100% 80%

3rd Party

60% 40%

Pilots

20% 0% 2010 2011 2012

Ground OperaEon Team

Figure 4 2010 to 2012 Party at Fault Trend

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100% 80%

Marshaller

60%

Driver

40%

Ground Crew

20% 0% 2010 2011 2012 Figure 5 Ground Operation Team Fault Breakdowns
3.1.2.3 Phase of Incident

As shown in Figure 6, an increasing majority of incidents occur during push back as well as taxiing.

100% 90% 80% 70% Pushback/Parking

60%

Taxiing

50%

Parked

40% 30% 20% 10% 0% 2010

2011

2012

Figure 6 Phase of Incident

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3.1.2.4 Type of Damages
Figure 7 and Figure 8 shows the type and location of damage sustained by the aircraft respectively. It is shown that near contact took up more than half of the total type of damages each year. And the most common aircraft damage location is the wingtip. 35 unable to determine

30 25

Near contact

20

Minor Damage, repair deferred/ done in line

15

Damaged, Withdrawn from service

10

Contact, no damage

5 0 2010

2011

2012

Figure 7 Type of Damage

9 8

wheel/tyre

7

WingEp

6

Radome

5

Landing Gear

4

Fuselage

3

Engine cowling

2

Engine

1 0 2010

2011

2012

Figure 8 Location of Damage
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3.2

PAST GROUND OPERATION INCIDENT RESEARCH

From CAA Ground Handling Operation Safety Team (GHOST) data of 2008, as indicated in Figure 9, the most common type of human errors are mistakes. In the publication, it also shows the time of occurrence of incident (Figure 10). It can be seen that there are 3 peaks in the time of incident occurring, and they are approximately 9 AM, 3 PM, and 9 PM.

Figure 9 2008 Human Failure Trend (CIVIL AVIATION AUTHORITY OF UK, 2009)

Figure 10 Time of Occurrence (CIVIL AVIATION AUTHORITY OF UK, 2009)

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A report from International Air Carrier Association (ICAC) indicates that on average
20% of damage is not reported as shown in Figure 11.

Figure

11

Non-Reporting

Statistic

(INTERNATIONAL

AIR

CARRIER

ASSOCIATION, 2008)

3.3

COST ANALYSIS OF DAMAGE SUSTAINED ON TRADITIONAL AIRCRAFT

Costs incurred by AO due to ground operation incident involving aircraft can be broken down into 2 types. They are direct cost and indirect cost.
Direct costs also known as hard cost are any cost incurred to repair or replace the damaged parts. From Figure 12, a breakdown of the cost of replacement for certain parts commonly damaged during ground operation for a Boeing 737-700 can be seen. However, these figures are from a report by Boeing Commercial Airplanes
Group in 2002, it might not accurately portrait the cost in todays’ monetary value. In this instance, it is decided that these cost has to be adjusted for inflation from 2002 to 2013. Based on the inflation rate from 2002 to 2013 from Table 1, the new cost of replacement are calculated cumulatively, and shown in Figure 13.
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Figure 12 Cost of Ramp Damage (2002) Source: Boeing Commercial Airplanes
Group
Year

Inflation Rate

2002

1.6%

2003

2.3%

2004

2.7%

2005

3.4%

2006

3.2%

2007

2.8%

2008

3.8%

2009

-0.4%

2010

1.6%

2011

3.2%

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2012

2.1%

2013

1.5%

Table 1 2002 to 2013 Inflation Rate

Figure 13 Cost of Ramp Damage (2013)
Indirect costs are soft cost incurred due to the incident, and certain of this soft cost are not quantitative. There are a number of indirect costs, they include;
•

Lost revenue from ticket sales, where the aircraft is removed from service and loses the opportunity to help the company make revenue.

•

The cost of diverting another aircraft to replace the damage aircraft such that the service is not interrupted.

•

The cost of providing food and accommodation to passenger that has missed the flight or connecting flight.

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•

The perceived cost of damage to the company’s public image. The cost associated with flight cancellation, e.g. compensation to passenger, and/or arranging alternate means of travel to the passenger.

With the above reasons, indirect costs are very difficult to evaluate as certain cost are perceived, while some are dependent on the number of affected passengers.
Indirect cost is also said to be significantly higher than direct cost.
Ferry (1988) claimed that an “estimates of the indirect costs of mishaps range from twice as much as the direct costs to 200 times as much. A conservative estimate is that the indirect costs average three times the direct costs.” In this report, the indirect cost multiplier will be based on Ferry (1988) conservative estimate of 3 times the direct cost.
As the extent of damage cannot be determined in Section 2.1.2.4, and certain type of repair cost could not be determined, an accurate assumption could not be made. In such instance, the median of the range of damage cost from Figure 13 will be used for the calculation of fiscal impact. The median came out to US$226694, and it will be multiplied with the number of damage from Figure 7 to obtain the direct cost. And as discussed earlier, the indirect cost will be 3 times the direct cost. The direct and indirect costs of incident with damage are calculated and can be seen in Figure 14.

$12,000,000.00 $10,000,000.00 $8,000,000.00 Indirect Cost $6,000,000.00

Direct Cost

$4,000,000.00 $2,000,000.00 $0.00 2010

2011

2012

Figure 14 Actual Incident Cost

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Assuming all reported incidents are to have suffered damage, the fiscal impact can be seen in Figure 15.

$30,000,000.00 $25,000,000.00 $20,000,000.00 Indirect Cost $15,000,000.00

Direct Cost

$10,000,000.00 $5,000,000.00 $0.00 2010

2011

2012

Figure 15 Incident Cost (Assumed Damage Sustained on All Incident)

3.4

IMPACT DAMAGE ON AIRCRAFT MATERIALS

As discussed in Section 2.4, literature research on impact damages are carried out for metals and FRP composite. The type of impact damage seen on metal will typically be a dent or puncture. Assuming the force of the impact is similar on different metallic materials, the extend of the damage are dependant on the material properties, such as it’s hardness, young modulus, resilience, ductility, and etc. E.g. harder material will not necessarily dent, but it’s more sceptical to shattering, compared to a softer, more ductile material.
If the damage area on a metallic material is not repaired, it will create a localised stress concentration point, causing most stress to act on that localise point with each loading, till it fracture. However, before fracturing, permanent deformation on the metallic material can be observed easily, making it relatively easy to spot during inspection. Base on Figure 16, it can be seen that the energy absorption for FRP composite material with high modulus are lower. This would indicate that they are more
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susceptible to impact damage, and material failures can occur without deformation.
Impact damage associated with FRP composite material can be broken down into 2 types, and they are Visible Impact Damage (VID) and Barely Visible Impact Damage
(BVID). VID are damages that are visually recognisable during inspection with our naked eyes, as it is typically indicated with some form of surface deformation.
Whereas BVID are completely the opposite, the impacted area has very minimal surface deformation, and it might even return to its original shape, making it difficult to spot during inspection. The only ways to detect BVID damages are to perform Non
Destructive Testing (NDT) on the materials, such as the tap test, ultra-sound imaging, and x-ray.

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High Strength CFRP

High Modulus CFRP

Lower
Modulus/Strength
CFRP

Experimental

GFRP

CFRP

Figure 16 Charpy Impact Energy of Composite Material (BADER, M.G et al.,
1972)
There are 6 possible types of impact damage sustainable by FRP composite materials, and they are fibre fracture, fibre disbonding, matrix cracking, dents, punctures, and crushed sandwich core. These impact damages affect VID, and BVID with the exception of dents and punctures, since it is barely visible.
If these damages are not repaired, it could cause the damage to propagate during loading and ultimately failure. The damage would also subject the composite fibre to
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the environment, especially water ingress. As composite fibre materials are typically hygroscopic in nature, the matrices propose was also to seal the fibres from the environment. When damage occurs, the matrix will be compromised, causing the fibre to absorb moisture in the air. This could result in secondary failure due to disbonding between the fibre layers as moisture is absorbed.
3.5

COST ANALYSIS OF DAMAGE SUSTAINED IF IT IS A HIGH RATIO
COMPOSITE AIRCRAFT

As discussed in 3.5, in order to interpolate the result for high ratio composite aircraft, the specific strength factor between the 2 material used, the cost difference factor between the 2 type of material, and the cost difference factor in production cost between traditional and high ratio composite aircraft is required.
Since the cost analysis of damage sustained on traditional aircraft is based on a
Boeing 737-700, it is important to know the material composition of those parts listed in Figure 13.
In the Boeing 737-700, most of the aircraft parts are fabricated using different grade of aluminium. However, there are certain parts that are fabricated using FRP composite material, like Fibreglass, Aramid, and Carbon laminate. Fibreglass is used to fabricate the following parts; radome, tailcone, centre and outboard flap track fairing. Aramid is used to fabricate the following parts; engine fan cowl, inboard track faring (behind engine), and nose gear doors. Carbon laminate composite is used to fabricate the following parts; rudder, elevators, ailerons, spoilers, thrust reverser cowls, and dorsal of vertical stabilizer.
To mimic the cost of current generation of high ratio composite aircraft, the material composition of these parts will follow the Boeing 787. From Figure 17, it can be seen that the Boeing 787 uses 50% composite material and 50% metal. A side-by-side comparison of material used for the list of parts identified in Figure 13 can be seen in
Table 1.
The 3 main common materials identified in the traditional aircraft and high composite ratio aircraft are aluminium, carbon laminate composite, and carbon sandwich composite. Therefore, there are 3 material comparisons to be made for the multiplier, and they are aluminium to carbon laminate composite, aluminium to carbon sandwich composite, and carbon laminate composite to carbon sandwich composite.
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With these information, the material cost difference could be determined. Since it is a function of the raw material price, the cost of aluminium and carbon laminate composite are found to be, US$1.80/Kg, and US$110/Kg respectively. However, the search for cost of aerospace grade carbon sandwich composite was inconclusive.
Thus, the cost for carbon sandwich composite is assumed to be similar to carbon laminate composite. A discount of 70% will be levied on the material cost ratio as the manufacturer typically could get bulk discount and the parts may not be made purely of composite materials. Therefore, the cost difference multiplier for aluminium to carbon laminate composite and aluminium to carbon sandwich composite is found to be 18.33 times. And carbon laminate composite to carbon sandwich composite to be
1 times.

Figure 17 Boeing 787 Material Compositions
Parts

Radome Main Entry Door Cargo Door Inlet Cowl Leading Edge Slat Assembly Aileron and Tab Assembly Outboard Flap Assembly Inboard Flap Assembly Wingtip Elevator Assembly

737-­‐700 Fibreglass Aluminium Aluminium Aluminium Aluminium Carbon Laminate Composite Aluminium Aluminium Aluminium Carbon Laminate Composite

787 Fibreglass Carbon Laminate Composite Carbon Laminate Composite Aluminium Aluminium Carbon Laminate Composite Carbon Laminate Composite Carbon Laminate Composite Carbon Sandwich Composite Carbon Sandwich Composite

Table 2 Boeing 737-700 and 787 Material Differences

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The next multiplier required is the specific strength factor between the 2 types of materials. The material properties for aluminium and carbon laminate composite can be seen in Table 3. The specific strength of the material is calculated and also shown in the table. However, material properties for carbon sandwich composite could not be found, it is then assumed to have 20% reduced weight of carbon laminates composite since the purpose of the sandwich core was to reduce weight while maintaining strength.
Materials

Density

Young’s Modulus

Specific Strength

Aluminium

2.7g/cm3

70GPa

25.926GPa/g/cm3

Carbon Laminates Composite

2g/cm3

300GPa

150GPa/g/cm3

Carbon Sandwich Composite

1.6g/cm3

300GPa

187.5GPa/g/cm3

Table 3 Material Properties
The specific strength multiplier for aluminium to carbon laminate composite, aluminium to carbon sandwich composite, and carbon laminate composite to carbon sandwich composite is found to be 0.173, 0.138, and 0.8 respectively.
The last parameter required is the cost difference in production cost between traditional and high ratio composite aircraft materials is required. Since this parameter varies with different parts, and the companies keep the fabrication process confidential. This value will be calculated base on the repair process of each material, which is the time needed to carry out an aluminium flush skin repair, composite laminate flush repair, and composite honeycomb flush repair on an aircraft. All scenarios will be based on a 3-inch diameter radial puncture on the fuselage skin.
With aluminium patch repair, the damage area is removed with an addition of approximately 1-inch material around it. 2 piece of new material is needed to perform the repair, a doubler plate and a cut out. The doubler plate has to be at least 4inches wider than the cut out area. The doubler plate will be secured on the back of the skin with 2 rows of rivets, 1 inch from the edge of the doubler plate, and 1 inch from the cut out edge. The gap distance between each rivet will also be 1 inch apart.
The cut out piece will be secured on the double plate with a row of rivets, 1 inch from the edge and 1 inch apart for each rivet. An example of a completed aluminium skin
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flush repair is shown in Figure 18. The preparation of material, to mark out and cut out will require approximately 4 hours. There are approximately 30 rivets for this repair. Assuming the time required to drill, counter sunk and secure each rivet is 2 minutes, the required time for this task would be 1 hour. Therefore, the total time required for this repair will take 5 hours.

Figure 18 Aluminium Flush Skin Repair
Composite laminate flush repair, involve taper (30 to 60 degree) sanding away the damage, while also exposing each ply of laminate. The dimension for each ply are taken and marked out on the new material, and subsequently cut. The layers are stacked together (assuming pre-impregnated fibre are used where there is no need to mix and apply the matrix on the fibre), and a hot bonder machine is used to cure the composite. The surface will then be sand to smoothness. A breakdown on a composite laminate flush repair can be seen in Figure 19. The preparation time required for sanding the damage, marking out the dimension for the replacement plies, and cutting it will take approximately 4 hours. An additional 1 hour is required to layout the plies and setup for use of the hot bonder. The curing cycle of the hot bonder will take approximately 10 hours. Sanding it to smoothness will require a

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further 30 minutes. Therefore, the total time required for this repair would be 15.5 hours. Figure 19 Composite Laminate Flush Repairs
As for composite sandwich flush repair, the process is pretty similar to laminate flush repair. The top damage surface is taper-sanded, and the honeycomb core is removed and replaced. The top plies are marked out, cut, and stack covering the honeycomb. The same is done to the lower surface damage area. A hot bonder machine will be used to cure the composite. After the curing cycle the surface is sand to smoothness. A step by step of how a composite laminate flush repair is carried out is shown in Figure 20. The preparation time required for sanding the damage, marking out the dimension for the replacement plies, preparing the honeycomb, and cutting it will take approximately 5 hours. An additional 3 hour is required to layout the plies and honeycomb, and setup for use of the hot bonder. The curing cycle of the hot bonder will take approximately 10 hours. Sanding it to smoothness will require a further 30 minutes. The total time required for this repair would be 18.5 hours.

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Figure 20 Composite Sandwich Flush Repair
There are 3 different required cost multipliers for production cost which can be seen in Table 2. They are for aluminium to carbon laminate composite, aluminium to carbon sandwich composite, and carbon laminate composite to carbon sandwich composite. The cost multipliers for these differences are 3.1, 3.7, and 1.2 respectively. The multipliers are multiplied together to come out with the combined multiplier in
Table 4. With the combined multiplier and cost of traditional aircraft damage from
Figure 13, the cost for replacement can be interpolated for a high ratio composite

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aircraft. The compiled figure for high ratio composite aircraft ramp damage are calculated and displayed in Figure 21.

Material Comparison

Combined Multiplier

Aluminium to carbon laminate composite

9.831

Aluminium to carbon sandwich composite

9.36

Carbon laminate composite to carbon sandwich composite

0.96

Table 4 Material Multiplier

Figure 21 Composite Aircraft Ramp Damage Cost
Similar to Section 3.3, the direct and indirect cost are calculated based on the median cost of damage, which came out to be US$383045. By multiplying the median cost of damage and the number of incidents, the direct and indirect cost could be obtained. These figures are shown in Figure 22 and Figure 23.
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$20,000,000.00 $18,000,000.00 $16,000,000.00 $14,000,000.00 $12,000,000.00

Indirect Cost

$10,000,000.00

Direct Cost

$8,000,000.00 $6,000,000.00 $4,000,000.00 $2,000,000.00 $0.00 2010

2011

2012

Figure 22 Interpolated Composite Aircraft Actual Incident Cost

$50,000,000.00 $45,000,000.00 $40,000,000.00 $35,000,000.00 $30,000,000.00

Indirect Cost

$25,000,000.00

Direct Cost

$20,000,000.00 $15,000,000.00 $10,000,000.00 $5,000,000.00 $0.00 2010

2011

2012

Figure 23 Interpolated Composite Aircraft Incident Cost (Assuming Damage sustained on all incident report)

3.6

CURRENT LEGISLATION ON GROUND OPERATION SAFETY

The only legislation governing all ground operation oranisation is the Health and
Safety at Work etc. Act (1974) and ICAO Annex 14, with the exception of aircraft
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MRO organisation and aircraft maintenance personnel that are also governed by the
CAA part 145 and 66 regulation.
The Health and Safety at Work etc. Act (1974) purpose is to ensure that employees are provided with the necessary tools, knowledge, and safe environment during work. It does not specify any detailed requirements to follow, the employers are responsible to do and provide what they deem as necessary and within the confine of the Act.
The ICAO Annex 14 – Aerodrome Design and Operation, dictates the state to have a safety program such that an acceptable safety level in the aerodrome can be achieved. Safety Management System (SMS) is required to be implemented in all certified aerodrome.
The CAA Part 66 governs the licensing of aircraft maintenance personnel, which denotes the training requirement, personnel’s legal responsibility and etc. Where as the Part 145 governs the licensing of aircraft MRO organisations, which denotes the facilities requirement, personnel requirements, certifying staff, safety management system and etc. The CAA part 66 and 145 regulation, lists down all specific requirements needed to obtain and/or renew the license.
In 2003, the CAA came out with the CAA Mandatory Occurrence Reporting (MOR) scheme (CAP 382) to aid in the improvement of flight safety. The MOR (2011) prescribed that “Any incidents which endangers or which, if not corrected, would endanger an aircraft, its occupant, or any other person” has to be reported to the
CAA. The MOR also states the categories of aircraft and personnel to report under this scheme. The categories of aircraft cover under the MOR (2011) are “any aircraft operated under an air operator certificate granted by the CAA, and/or any turbinepowered aircraft which has a certificate of airworthiness issued by the CAA”. The personnel to report under the MOR are basically anyone that works on the aircraft.

3.7

CURRENT TECHNOLOGIES AIDING INCIDENT REDUCTION

There are currently two technological solutions aiding incident reduction and they are the RampTrack Ground Accident Avoidance System (GAAS) and External and
Taxiing Aid Camera system (ETACs).

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The RampTrack GAAS uses multiple sensors, cameras and computer to create an invisible safety zone around the aircraft, and it would alert the operator when it detects a possible threat, very similar to how the Traffic Collision Avoidance System
(TCAS) work on an aircraft. It even features a Customer Relationship Management
(CRM), Billing, and Authentication System.
However, this is a relatively new product, the effectiveness of the solution is unknown. And attempt to request for data and cost from RampTrack was unsuccessful. Figure 24 RampTrack Ground Accident Avoidance Systems
The ETACs uses camera mounted on the vertical stabiliser and belly of the aircraft to provide visual cues for the pilot during taxiing. The information are displayed on the
Primary Flight Display (PFD) screen in the cockpit as shown in Figure 25.

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Figure 25 A380 External and Taxiing Aid Camera Systems

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4 LIMITATION
In this report, there are 2 main limitations. The areas of limitation include, the cost figures and data selection.
4.1

COST FIGURES

The projected costs figures obtained in this report should only be used for comparison purpose only, and should not be taken as encompassing. These cost figures are based on the median of a range of damage cost. The cost also does not include the cost of damage to facilities, equipment and vehicles. It also does not include cost incurred due to injuries sustained by personnel, and/or passenger.
4.2

DATA SELECTION

Since there is only 1 source of data, diversity of data is not possible to cover all grounds. Thus, the data obtained from the CAA might not reflect the situation as a whole in the UK aviation industry. Furthermore, the CAA MOR scheme are only applicable to “aircraft operated under an air operator certificate granted by the CAA, and/or turbine-powered aircraft, which has a certificate of airworthiness, issued by the CAA. It does not include report of incidents involving foreign registered aircraft in the UK”.

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5 DISCUSSION
5.1

FISCAL IMPACT

As previously discussed, due to insufficient data, a proper assumption on the fiscal impact could not be made for 2010 to 2012. Instead, the median costs for the range of damage shown in Figure 13 were used to calculate the fiscal impact, and only to be used for the purpose of comparison. From Section 3.3, it can be seen that the median cost of each incident involving traditional aircraft could cost the Aircraft
Operator (AO) close to US$ 1 million. And if it happens to be a high ratio composite aircraft e.g. Boeing 787 or Airbus A350, the median cost of each incident would rise to slightly above US$ 1.5 million. This would equate to more than 50% increase in cost incurred by the AO, in the event of an incident involving high ratio composite aircraft. The overall fiscal impact for 2010 to 2012 based on the CAA data came out to an estimate of US$ 20 million. Now, to indicate how the fiscal impact could increase if no corrective action were to be taken, this report would assume that damage were sustain in all reported incidents. This cause the possible fiscal impact to sky rocket to an estimate of US$ 70 million, which would cost the industry to lose 3.5 times more due to ground operation incidents. If these aircraft were assumed to be of high composite ratio, the cost would rise to a staggering US$ 34 million (only incidents with damage), and US$ 114 million (assume all reported incidents sustain damage).
Thus, this shows the importance of reducing the number of incidents occurrence, to keep the fiscal impact to the minimal.
5.2

GROUND OPERATION TREND

To have a clear indication of the ground operation situation, an in-depth analysis of the recent years incident is required and the results are shown in Section 3.1. The ground operation incident data obtained and analysed from CAA for 2010 to 2012 were very similar to the data release by the CAA GHOST team in 2008. This should indicate the analysis carried out on the data to be reliable. It can also be seen that ground operation incidents are on the rise, even when there had been a decrease in aircraft movement.
The data points out that among all human failures, mistake are the number one cause. Mistakes occurs when operator are unfamiliar with a situation and attempts to
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solve it using either their best knowledge or a set of memorised rules, which are incorrect. The reasons for this mode of failure are primarily due to insufficient training, and/or complacency.
It can also be seen that most of the incidents happen during the pushback, parking or taxing phase of the aircraft, and the majority of offenders are from the ground operation team. Since the ground operation team consist various personnel, it is then further broken down into their job scope, and it is found that drivers are the major offenders. Some possible reason could be because the ground is a highly dynamic environment and ground operation can be a highly repetitive job. This would cause personnel to become complacent when an unfamiliar situation arises.
There are also 3 peaks in incident occurrence in a day; they are at 9 AM, 3 PM, and
9 PM. These timings happen to coincide with 1 to 2 hour after meal, which could be an indication of postprandial somnolence. Postprandial somnolence is a condition where the body fall into a state of low energy due to parasympathetic activation. It also indicates that the larger the meal, the more restless the person will feel. This could pose a threat, as the operator may not be attentive and/or causing him/her to rush the work such that he/she is able to rest.
Based on researches from IACA, it is also found out that about 20% of the incidents are not reported. Possible reason for non-reporting of incidents could be the fear of trouble, lengthy paperwork, unaware of the situation, and etc. This would pose a threat to high ratio composite aircraft, as composite materials are susceptible to impact damage as discussed in Section 3.4. There are also instances where these damages could not be seen on the surface, which could lead the personnel to think there is no damage. This damage is known as Barely Visible Impact Damage
(BVID).
5.3

COMPOSITE MATERIAL DAMAGE

BVID are very difficult to detect, and could give the false impression that the structure suffer no damage. If continuous loading is applied on the damaged structure, it could cause the damage to propagate and ultimately failure. It is also shown that damage from composite could happen abruptly, which meant it would be similar to having a time bomb waiting to go off. The worse scenario would be a failure while the aircraft is in flight, where the aircraft integrity could be severely
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compromise. It could cause problem such as explosive decompression of cabin, failure of control surface and etc. All of which could lead the aircraft to ultimately crash, killing everyone on board the aircraft. Thus, it is important that all incidents are reported. 5.4

SOLUTIONS

There are a number of systems that could possibly help reduce ground operation incidents. These systems include, human factor program, regulatory tightening,
ETACs, RampTrack GAAS and any other technological systems.
5.4.1 Human Factor Program
Human factor program has been used in the aviation industry for quite some time. It is based on extensive research on personnel’s qualification, training, motivation, safety, health, professionalism, human capabilities and limitations. The Safety
Management System (SMS) and Fatigue Risk Management System (FRMS) are developed as part of the human factor program.
The SMS framework can be split into 4 component, safety policies and objectives, safety risk management, safety assurance, and safety promotion. The purpose of the
SMS is to continuously monitor and evaluate any safety risk and pattern, such that it can be dealt with systematically. It also ensure the risk has been dealt with, such that it would not occur again. Safety promotion is conducted regularly to educate the personnel on newly identified safety risk or rising safety risk.
The FRMS on the other hand is defined by ICAO as “a data-driven means of continuously monitoring and maintaining fatigue related safety risks, based upon scientific principles and knowledge as well as operational experience that aims to ensure relevant personnel are performing at adequate levels of alertness”. The main purpose of the FRMS is to assess risk associated with sleep deprivation, and circadian rhythms. It is currently only used in conjunction with the flight crew Flight
Time Limitation (FTL) Scheme, where flight crew are bounded by the regulation of their flight and duty time limitation. With the FRMS, operator may apply to the regulatory authorities for extension of the FTL by addressing certain fatigue risks.
While SMS is required in any aerodrome operation under the ICAO annex 14
Aerodrome Design and Operation requirement, the FRMS are not mandatory under the requirement of the law for ground handling organisation.
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5.4.2 Regulating Industry
As discussed in Section 3.6, there isn’t much legislation in place to regulate the industry. However, there are guidelines available to IATA members, which is the
IATA Ground Operation Manual (IGOM). The IGOM lists down all ground operation procedure with the best safety practice. IATA also came out with a safety audit scheme known as the IATA Safety Audit for Ground Operations (ISAGO) for any airlines as long as they are IATA Operational Safety Audit (IOSA) registered. The
ISAGO is a free cross-company audit scheme, where each company has to have a qualified safety auditors trained by IATA, and once a year, the safety auditors will be allocated to another company within its pool of members to perform the ISAGO checks. The purpose of this scheme was to prevent any oversight within the company. Regulatory tightening of the ground handling operation industry should also be considered in reducing the incident occurrence. Companies involved in ground handling should be regulated with standards similar to the CAA Part 145. Where companies are required by law to have systems in place to ensure the safety of the personnel and aircraft, detailed personnel’s requirement, and facilities requirement.
Personnel involved in ground handling should also be regulated with similar standard to the CAA Part 66. Which it will denotes the mandatory training requirement, maximum working hour, and outlines the personnel’s legal responsibilities. This would ensure all ground-handling personnel have adequate training, and equipped with the knowledge and information required for the job. It will also reduce fatigue related risk due to over-time, and could reduce non-reporting of incident.
Reporting procedure of incident should also be made anonymous and simple, such that the incident reporter would not have the fear of trouble and lengthy paperwork associated with it. This should help reduce the non-reporting of incidents, which could be detrimental to high composite ratio aircraft as discussed previously.
5.4.3 Introducing Technology to the Industry
National Transport Safety Board (NTSB) of United State has found that the ETACs would be useful in reducing the number of incident relating to large aircraft wingtip clearance, and had issued a safety recommendation to European Aviation Safety
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Agency (EASA) on September 2012. They recommended to the authority that
ETACs should be made compulsory on all new large aircraft, and current fleet of old large aircraft to be retrofitted with it. Till date, the safety recommendation was not implemented. However, the ETACs has a weak point, the camera view angle isn’t wide enough to cover the wingtip as seen in Figure 25. It is also only used during powered taxiing by the pilot only. To further improve the effectiveness, the camera should be changed to one that cover the wingtip, and ground crew should be allowed to access the system during aircraft ground movement too.
Since there is not much information available on the RampTrack GAAS, it will not be considered as a recommendation in this report.
There are also other technological methods that could be employed to reduce the occurrence. These include installing proximity sensors around the equipment or vehicle, when an object has exceeded the sensor’s threshold distance, an aural and visual cue will be provided to alert the operator. The concept is very similar on how the RampTrack GAAS work by creating an invisible safety zone and alerting the operator. However, this method would be a cheaper and much simpler solution, where the implementation of this solution could be possible by retrofitting car reverse sensor around the equipment and vehicle.

6 CONCLUSION
It is evident that any ground operation incidents can be costly to the industry. If incidents were not reduced, the cost incurred could sky rocket more than 3.5 times the current situation. And with high ratio composite aircraft, the cost incurred due to an incident is found to be approximately 50% more than traditional aircraft.
Therefore, it is of paramount importance to reduce the number of incidents. This report would also include some recommendations to reduce the number of incidents in Section 7.

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7 RECOMMENDATIONS
7.1

REGULATING THE GROUND OPERATION INDUSTRY

The ground operation industry should be regulated as discussed in Section 0. The organisation as well as the personnel should be regulated. However, the regulation should be implemented in stages to facilitate the transition.
The personnel regulation should require all new personnel to passed all required training and test before the start of work. And, current personnel are required to pass all required training and test within 2 years. This should ease the impact on shortage of manpower due to the new regulations. The scope of the training and test should include but not limited to, airside driving safety, safety risk identification, correct working procedures, and personnel’s legal responsibilities.
Some form of Flight Time Limitation (FTL) on ground operation personnel should also be considered. This should reduce any fatigue related incidents.
Where as for the organisation regulation, the organisation will have 3 years to align with the new regulations. The regulation should include the mandatory requirement to have an audit scheme carried out by a qualified 3rd party, similar to the IATA
Safety Audit for Ground Operation (ISAGO), reducing the risk of organisation oversight. Companies could also use Fatigue Risk Management System (FRMS) to extend the FTL of their personnel if necessary.
7.2

INTRODUCING TECHNOLOGIES TO THE INDUSTRY

External and Taxiing Aid Camera system (ETACs) should be made compulsory on all large aircraft, similar to what National Transport Safety Board (NTSB) of United
State has recommended. However, to improve the effectiveness of the system, the camera has to be changed to provide a wider view such that it covers the wingtip.
The system should also be made available to the ground operation personnel during towing. By allowing ground operation personnel access to ETACs, the total personnel required during towing could also possibly be reduced, as there isn’t the need for the wingman. The personnel in the cockpit would have a visual of the wingtip through the ETACs, this would reduce the labour costs.

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Installation of proximity sensors on equipment and vehicles should also be considered, as it would create a cheap and effective invisible safety zone, which could alert the operator when the safety zone is breach.

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ABBREVIATIONS AND ACRONYMS
Aircraft Operator

(AO)

Civil Aviation Authority of United Kingdom

(CAA)

International Civil Aviation Organisation

(ICAO)

International Air Transport Association

(IATA)

Airport Council International

(ACI)

Fibre Reinforce Plastic composite

(FRP)

Singapore Airline

(SIA)

British Airways

(BA)

Maintenance Repair Overhaul

(MRO)

Singapore Technology Aerospace Engineering Ltd

(STaero)

SIA Engineering Company

(SIAEC)

Hong Kong Aircraft Engineering Company Ltd Singapore

(SHEACO)

Carbon Fibre Reinforced Plastic

(CFRP)

Glass Fibre Reinforced Plastic

(GFRP)

Aramid Fibre Reinforced Plastic

(AFRP)

Mandatory Occurrence Reporting

(MOR)

Ground Handling Operation Safety Team

(GHOST)

International Air Carrier Association

(ICAC)

Visible Impact Damage

(VID)

Barely Visible Impact Damage

(BVID)

Non Destructive Testing

(NDT)

Ground Accident Avoidance System

(GAAS)

External and Taxiing Aid Camera system

(ETACs)

Primary Flight Display

(PFD)

United Kingdom

(UK)

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United State

(US)

Safety Management System

(SMS)

Fatigue Risk Management System

(FRMS)

Ground Operation Manual

(IGOM)

IATA Safety Audit for Ground Operations

(ISAGO)

IATA Operational Safety Audit

(IOSA)

National Transport Safety Board

(NTSB)

European Aviation Safety Agency

(EASA)

Traffic Collision Avoidance System

(TCAS)

Customer Relationship Management

(CRM)

Flight Time Limitation

(FTL)

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8 REFERENCES
BADER, M.G, J.E BAILEY, and I BELL. 1972. The effect of fibre-matrix interface strength on the impact and fracture properties of carbon-fibre-reinforced epoxy resin composites. Surrey: University of Surrey.
CIVIL AVIATION AUTHORITY OF UK. 2009. GHOST DATA 2008. [online].
FERRY, Ted S. 1988. Modern Accident Investigation and Analysis. [online].
INTERNATIONAL AIR CARRIER ASSOCIATION. 2008. Ground Safety IACA aircraft ground damage database and results. [online].

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9 BIBLIOGRAPHY
AIRBUS. 2006. A380-800 Flight Deck and Systems Briefing for Pilots. [online].
AIRPORT COUNCIL INTERNATIONAL. 2005. ACI Apron Safety Survey Overview.
[online].
AIRPORT COUNCIL INTERNATIONAL. 2005. ACI Survey on Apron
Incidents/Accidents 2004. Geneva: ACI World Headquaters.
BADER, M.G, J.E BAILEY, and I BELL. 1972. The effect of fibre-matrix interface strength on the impact and fracture properties of carbon-fibre-reinforced epoxy resin composites. Surrey: University of Surrey.
BOEING. 2013. Boeing 737 Structural Repair Manual. [online].
CAA. 2013. Aircraft Movement 2002 to 2012. [online].
CAA GHOST TEAM. 2009. Ground Handling Mandatory Occurence Reports.
[online].
CIVIL AVIATION AUTHORITY OF UK. 2009. GHOST DATA 2008. [online].
FERRY, Ted S. 1988. Modern Accident Investigation and Analysis. [online].
FLIGHT SAFETY ORGANISATION. Cost of Ramp Damage. [online].
INTERNATIONAL AIR CARRIER ASSOCIATION. 2008. Ground Safety IACA aircraft ground damage database and results. [online].
NATIONAL TRANSPORT SAFETY BOARD US. 2012. Safety Recommendation.
Washington DC: National Transport Safety Board US.
SAVAGE, Gary and Mark OXLEY. 2008. DAMAGE EVALUATION AND REPAIR OF
COMPOSITE STRUCTURES.
SKYBRARY. Skybrary. [online]. [Accessed 2013]. Available from World Wide Web:

TEAM SAI CONSULTING SERVICES. 2012. MRO Trends in Composite Repair Past
Experiences and Future Challenges. [online].
VANDEL, Bob. 2004. Equipment Damage and Human Injury on the Apron Is it a cost of doing business?.

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