COST OF POOR QUALITY

This article refers to the airport ground handling industry. That is where our expertise, such as it is, lies. What does that mean to you as a member of the public? Well, if you fly, you are a customer of the ground handling industry:

If you’ve landed at an airport without enough airbridges and the bus they used to take you to the terminal broke down and you missed your connecting flight; that’s ground handling,

If you waited a very long time at the Baggage Hall for your luggage; that’s ground handling,

When your case arrived, it was damaged, that was ground handling.

So, the lessons that apply to ground handling also apply to other industries, if a bus breaks down, that is as much of a problem as your Robot welder breaking or your banks’ ATM machine breaking down.

The highest quality producer of a good or service is often the lowest cost producer. This is because the Cost of Poor Quality (COPQ) or, technically, the Cost on Non-Conformance with the quality standards, is lower in their organisations.  Production of high-quality services requires investment in equipment, people, and processes. The production of poor-quality services creates significant, often intangible, costs.

There are four categories of COPQ costs:

  • Prevention costs are costs incurred to keep failure and appraisal costs to a minimum,
  • Appraisal costs are costs incurred to determine the degree of conformance to quality requirements,
  • Internal failure costs are costs associated with failures found before the customer receives the service,
  • External failure costs are costs associated with failures found after the customer receives the service.

It can be argued that Prevention and Appraisal costs are strictly Cost of Quality while the Failure costs are the Cost of Non-Conformance to standards. As you can understand, the external costs of failure are difficult to determine; you will never know, for example, if a potential customer lost interest because of your poor service. While for Deming measuring CoQ was a waste of time, Joseph Juran and Philip Crosby saw a need for it. They believed that as defect prevention was increased, the cost of rework would decrease by much more than the increase in prevention costs. The net result was lower total cost, and thus “Quality is free” (Crosby, 1979). Cost of Quality: [A Survey of Models and Best Practices Andrea Schiffauerova, Vince Thomson McGill University Abstract.]

Cost of poor quality are those costs which would disappear if our products and processes were perfect [Juran, J.M., Juran on Quality by design, Page 119, 1992, Free Press, ISBN 0-02-916683-7]

Prevention Costs

These are costs that are incurred to prevent failure. An example would be regular equipment maintenance and training.

Appraisal Costs

These are incurred to be sure that everything is working as planned. You do this all the time; before you leave on a journey in your car you check your tyres and fuel.

Internal Failure Costs

The costs incurred when failures in the service are detected before delivery to the customers such as:

  1. Equipment repair,
  2. Rework

External Failure Costs

The costs incurred when failures are found the by customers in actual use. You don’t need to be told that this is the worst kind of the cost of non-conformance.

These include:

  1. Rework.
  2. Public Liability.
  3. Loss of business reputation.
  4. Customer loss.
  5. Loss of market share.
  6. Penalties.

COPQ may be expressed in numerical form as a percentage of turnover, and mathematically using the four factors:

COPQ = Prevention + Appraisal + Internal and External failures.

Many organisations consider only the third and fourth factors (failures), which are the sum of rework, penalties, and so forth. They often think that customer satisfaction levels comparable to, competitors are good enough. “We’re no worse than anyone else” is their brand promise. (Morrison 2019.) But what if your organization looked at the equation as a complete system? Failure is still considered, but preventing errors from happening, and catching them in production, are equally important. You will have a prevention-based system that will result in in an improvement in customer satisfaction.

Prevention

The best way to lower the cost of poor quality is to prevent poor quality services from being produced and delivered in the first place. This is where the biggest gains are possible. Investment in prevention results in higher customer satisfaction, which is often difficult to measure but at the same time the most important factor to company success. The ground handling industry can measure customer satisfaction by a lack of complaints. Airlines are exacting customers, they do not like having their passengers waiting for baggage so they will readily complain about poor service. This makes it easier for ground handlers as they are always aware of any shortcomings in their service. Food manufacturers, for example, unless they actually poison people, get no such feedback, people just stop using the product.

Prevention actions include:

  1. Failure Mode and Effects Analysis,
  2. Training including refresher training,
  3. Maintaining equipment according to the manufacturer’s specifications,
  4. Safe working conditions; wearing personal protection equipment, for example,
  5. Good working hours planning; rest periods; much of the work is manual as very tiring,
  6. Sensible shift planning. Poor shift planning can lead to chronic fatigue which is bad for the workers but also bad for the handler as tired workers make mistakes,
  7. Pilot projects for new types or new methods of handling,
  8. Process Capability / Process Performance analysis.

Appraisal

This part of the equation represents the cost of measuring quality throughout the process. Aircraft pilots do this as a matter of course. Some examples are:

  1. Drivers checking the GSE before they take it from base,
  2. Internal Audit checking that the arrival/departure teams are at the stand in terms of the Service Level Agreement (SLA) between the ground handler and the airline,
  3. Changes in aircraft type or parking bay are communicated to the assigned team members? I flew into JNB once and the aircraft type and stand had been changed. The team supervisor saw his plane taxying past so he chased it in a passenger steps unit and placed it at the aircraft. Needless to say, the steps were wrong for the aircraft and the pax had to step down onto the steps which caused some caustic remarks by the pilot.

The better you do prevention, the less you will spend on appraisal.

Failures generally

Failures can result in much more than the costs of rework, reputation, penalties, and future business loss are some of the more obvious consequences. Legal claims caused by defective services can be a major expense.

If you do Prevention and Appraisal well, you will have fewer failures.

Internal Failure

This factor in the equation represents issues after the service has been performed but before the customer finds out, such as, rework (putting baggage on the correct aircraft,) equipment replacement, and so forth.

External Failure costs include:
Complaint adjustments, Penalties for non-conformance with ground handling agreement terms.

Be aware that some external failures may be perception issues, for example, that there were insufficient buses when there, in fact, there were.

GROUND HANDLING QUALITY MANAGEMENT

You’re in a quandary – your boss has just told you that you must put in a Quality system for your Ground Handling company. When you asked him what your scope was, he mumbled. You suspect, strongly, that he does not know what a Quality system is and what it entails. You have a vague idea but you can find out more. You get the impression that it will be difficult to get funding for more than a token effort. Worse than that, it is unlikely that the Operations people will look kindly on your project. Even worse than that, the airline industry, though mostly identical in Operations has important differences. For example, one airline might want cargo delivered to the bay 1 hour before departure, others might want more or less. Add to that, different times of day mean different number of passengers and baggage and different days and seasons also mean the same. So, you don’t have a homogeneous product as you would if you worked in a factory, for example.

What to do?

I will highlight the most important points in Bold. Italics. Brackets. Underlines

We will assume that resigning isn’t an option. You need to find out more so that you know where to begin. Before you do that, you need to know what to look for so that you have a set of questions for when you start searching for the methods you will use to measure quality.

Since it is unlikely that Operations will be willing to be measured you will have to find something to measure that will have the least objection to. I suggest Safety, particularly the wearing of Personal Protective Equipment, like reflective jackets, ear protection and so on. The airport may be monitoring that already so the workers are accustomed to it.

You will need to present your findings – the number of staff members without reflective jackets or not using the flasher on their vehicles if this is required – in some sort of chart. Charts are good because they show how things have changed over time. For better or worse or even if they have not changed. The chart you will use is called a Statistical Process Control chart.

I suggest that the easiest chart for you to use will be either the P or Np charts. I have used the P chart and it works well. The P stands for percentage that met your criterion; in this case, the percentage of people you checked that are actually wearing reflective jackets. The Np chart shows the percentage of people checked that were not wearing reflective jackets or whatever you are auditing. The rule that staff should wear PPE are known as Specifications in Quality jargon. If the customer – an airline or the airport sets the standards these are called Customer Specifications in. It does not matter whether the safety regulations are set by your own company or another party like the airport, labour union, national safety laws, or the airlines. In Quality Management these are generally set by customers. Some Quality Conscious companies set the internal specification themselves. This may or may not doesn’t apply to your company. For example, in manufacturing, the customer may specify that a part or product must be no bigger than 5mm or no smaller than 4.9mm. In the ground handling industry, the customer may specify that off-loading equipment should be at the bay no later than 30 minutes before arrival or that not less than 3 buses are waiting at the bay at arrival. Because most customers specifications in the ground handling industry are one sided – only one specification – not later than, not less than, and so on the P and Np charts are easier to use. Baggage handling is another example. Most airlines will set maximum times for 1st class baggage to be delivered to the baggage handling centre. There is no minimum time. I have found that, given half a chance, the baggage people will record 1st class bags as arriving before touchdown. I am not joking, I have seen it happen.

The other advantage of the P and Np charts is that the sample size can vary. The Sample Size is the number of measurements you should take in order to get a reasonable picture of the Process Quality. In manufacturing, for example, if bus doors are being spray-painted, there may be 5 or 6 checks done at random all over the door to check for under or over-painting – whether the paint coat is too thin or too thick. When using P or Np charts you can take a sample of any reasonable size, 1 or 2 or 5 is not reasonable – too small. You just check, say 30 staff members and count the number wearing reflective jackets. Say you find that there were 24 wearing their vests. This works out to 80% wearing vests for the P chart and 20% not wearing vests for the Np chart. The sample size may vary; at off-peak times there may be fewer people on the ramp than at peak times so your sample may be as small as 10. That is the beauty of the P and nP charts.

If you work for an FBO, the principle is the same except that your samples may be smaller. You will have different standards from a ground handler handling passenger aircraft. An FBO quality controller might check the passenger lounges for ashtrays not emptied or meal trays not cleared.

You get the idea.

These charts can be used in other areas, for example:

  1. The number of in/correct invoices sent to customers.
  2. Maintenance Job cards not signed off.
  3. Workers late for shift.
  4. Customer complaints.
  5. Fire extinguishers not serviced

    And many more.

    To summarise:

    P- and nP-charts are used to:

  • Detect sudden changes in processes, which you can trace to a specific cause like congestion which may cause delays in GSE getting to aircraft.
  • Provide information for you to decide if you need to stratify the data into subgroups, like location, employee, team, day of week, or time of day.
  • Show whether the system is stable that is, in control. This means that though there is some normal variation in the process, there are no really bad variations or as we say in quality, no “out-of-control” readings.
  • Compare systems before and after a major change. For example, cargo delivery times before and after training.

    By now you are asking: “Out of-control?” This means that a measurement or reading is outside the Control Limits. You will learn how to calculate Control limits later in another article but at this point, if bags are recorded as arriving in the baggage centre before ATA that would be out-of-control and you would need to investigate this very quickly.

    However:

    P- and nP-charts are not very useful for tracking trends over time, or small shifts in the process like bags arriving a minute late at the baggage centre.

COMPUTERISED TECHNOLOGY

The use of computerized systems/modern technology eases the workload and improves efficiency of all and sundry, in all areas of life. Computerized systems are improving in leaps and bounds in all aspects of life and industry, ranging from Mobile/cell phones through to vehicles, manufacturing industry and in fact virtually all industries, too numerous to mention individually.

I couldn’t agree more with the use of computers to improve productivity and make life easier and more efficient, however, have we become too dependent on computers and have lost some personal “skills” and “abilities”?

This article focuses on the Aviation industry, more specifically ground handling and the Ground Support Equipment. At the outset, I must confess to not being any kind of computer expert and as such, I do subject myself (and welcome any comments from readers) to a lot of criticism. I do know and appreciate that there are backup systems to ensure safe operations, however can we efficiently take over if these systems go “Pear shaped”?

Whilst I do agree with and “support” the efficiencies which modern computer technologies have and are bringing about, there are a few issues which raise a bit of concern in the Aviation industry. Two examples come to mind, firstly the sad fatal crash of Air France A330 flight 407, where, despite backup systems, the computer systems went haywire, giving mixed conflicting signals to the cockpit crew. Reading through the accident report and findings and seeing the computerized simulation of the last minutes of the flight, from the CVR and Black box information retrieved showed that despite the sophisticated computer systems, things went badly wrong and resulted in the crash. With all due respect to a competent and experienced cockpit crew, the impression was gained that they were not able to “manually” get the aircraft under control. Comments have been made, by other experienced pilots, that flying crew have been become too dependent on computers and in some instances have forgotten/lost the ability to actually fly aircraft manually, especially in emergency situations. The second example is the problem currently experienced with the Boeing 737 max. While this is an ongoing investigation and I would not try to preempt any findings or outcomes, it has been generally accepted that the MCAS (Maneuvering Characteristics Augmentation System) computer program is “faulty” and played a role in two fatal crashes. Investigations are ongoing and there are other factors involved.

This brings me to Ground Support Equipment. Let me hasten to say firstly, that GSE Operators are not as thoroughly trained as Aircrew and that any defective systems do not have the same catastrophic results; I do consider that failure of computerized systems can lead to serious damage to aircraft, again caused in part to operators relying too much on the safety systems built into the GSE. To quote a couple of examples, In the case where proximity sensors fitted to passenger steps to warn operators when top platform is close to the fuselage, a warning light illuminate warning the operator. In my experience, some operators would watch for the light to illuminate, rather than to physically check on how close the platform was to the fuselage. Failure of the sensor unit resulted in a hard contact with the fuselage (fortunately as witnessed not causing any serious damage). Another instance noted was with a cargo loader, fitted with a sensor to automatically adjust the height of the front platform to “follow” the varying height of the cargo door sill during loading/offloading process. Again, some operators depended solely on the sensors to automatically adjust the platform height and not physically check and manually adjust the platform height. Although the potential for damaging the aircraft cargo doorsill is not great it does present a problem.

It is one thing highlighting problems and another, finding solutions! In these cases, in my view, thorough adequate training is required to ensure that operators are fully aware of possible “computer failures” and are proficient to operate GSE without the assistance of these systems, i.e. manual operation of the GSE.

More hazards

GSE – ELECTRIC VERSUS DIESEL

Alastair Gordon – author

An important trend in the Ground Handling industry is the increased use of Electrically powered GSE in lieu of Diesel powered GSE. This is a welcome trend and carries a number of advantages e.g. reducing air pollution at airports, reducing “carbon footprints”, some would also include noise pollution although this is debatable, when comparing jet engine noise to diesel engine noise!

With the development of more efficient batteries, the Electrically powered GSE has become more attractive to operators.

A costing study carried out a few years ago showed that the cost of ownership of Diesel vs Electrically powered GSE, Electrical items break even with diesel units after between 5 and 7 years.

All in all, a very positive outlook.

From experience (mainly with Battery powered baggage tractors), sometimes painful and expensive, we go back to maintenance of electrical GSE. Batteries are expensive and discussions with various manufacturers have resulted in different opinions. What all agree upon the importance of battery maintenance cannot be over stressed. One of the drawbacks of battery powered GSE is the duty cycle between charges. Factors which will influence the duty cycle are the number of units owned by the operators, flight frequencies and in some cases, the ambient weather conditions. Manufacturers often claim a duty cycle of up to 8 hours between charges.

Some considerations regarding the efficient use of battery powered items are:

  1. Ensure that battery chargers are fully compatible with the batteries used. Battery manufacturers usually provide the charger requirements when supplying the batteries.
  2. A cost study showed that in certain cases, where high usage of the battery powered items, it is economically viable to purchase a “spare” battery for the various items of GSE. This battery can be fitted to the item when battery power is depleted and unit can be returned to service in a short time, rather than wait for the battery to be recharged. The flat battery can then be checked, cleaned and recharged without delaying operations. It should also be taken into account that a spare battery costs less than a complete item of GSE!
  3. With regard to charging batteries, and this is where we have experienced conflicting advice from battery suppliers. Most manufacturers claim that the service life of a battery is 5-6 years before replacement is required. The question that arises is the charging of batteries. Two options available, i.e. “Opportunity charging” and “full charges”. By definition, “opportunity charges” entail putting the vehicles on charge between tasks, i.e. if the unit is idle for an hour or so, put it on charge to “top up” the battery, whereas “Full charges” are done when the battery power reaches the lowest level of operation without damaging the battery. Most, if not all items of GSE provide a warning that the battery power has reached the minimum safe level. Continued use of the item can result in the item “shutting down” when the battery reaches a level where damage to the battery will occur. Some battery manufacturers condone Opportunity charging, whilst others claim that opportunity charging shortens battery life and only “full charges” are recommended. The battery chargers can then go through the full cycle of charging, balancing charges and ensuring that all battery cells are evenly charged.
  4. Based on #3 above, it is very important that:
    1. Operators are fully trained in the use of battery powered items, especially with regard to continued use after low battery warning is reached. Murphy’s Law will “kick in” and the item will come to a stop at the most inopportune time, crossing a taxiway en route to an aircraft to name but 2!
    2. Staff manning the Battery charging station must be fully trained in battery maintenance, e.g. checking electrolyte levels and ensuring that these levels are correct at all times (devices are available to assist with the correct topping up of electrolyte), cleaning of batteries, checking of charging plugs, where applicable, changing of batteries, connecting of batteries to charges etc.
    3. Charging bays must meet all Airport Authorities requirements with regard to safety aspects, e.g. Fire Extinguishers as required and adequate ventilation.

Whilst most of this information is basic and “common sense”, assumptions should not be made that drivers and charging bay staff are aware of this and follow precautions/procedures.

More on airport noise

PARTS OF AN AIRCRAFT – CROSSWORD

Parts of an aircraft

1 2
   
3 4
       
5 6 7
                           
         
         
8 9
                   
           
10
               
       
11 12
             
13 14
               
15
         
16 17 18
                                 
19
             
20 21
               
22
                     
         
23
                       
24
           
25 26
                           
         
27
                   

Across

5.    Movable control surface mounted inboard on the wing trailing edge – the back end of the wing, – which can be lowered partially to increase lift or fully to increase drag and slow the aircraft down.

7.    Some smaller aircraft usually used for short distance travel, have their own stairs built into the cabin door for the passengers to enter or leave the aircraft.

8.    The fairing which encloses an engine

10.    The long bits that stick out the fuselage, more or less, horizontally. In flight they generate the lift that enables an aircraft to fly.

11.    Movable control surface mounted on the fin. It is used to change the direction in which the aircraft is travelling.

14.    What the people sit on.

16.    Devices mounted on the top of a wing to “spoil” the airflow across the wing to reduce lift. Alao called “lift dumpers.”

17.    The end of an aircraft.

18.    The small room in which meals and drinks are prepared.

21.    Fixed vertical control surface mounted on the tail. The fin controls the direction inwhich the aircraft is travelling.

22.    A gas turbine engine in which some of the air is ducted past the turbine and added to the jet exhaust.

23.    The large number of wheels mounted under the fuselage about where the wings joiin the fuselage.

25.    Hinged control surface mounted on the wing trailing edge which is used to contol rolling movements. Found outboard (near the tips.) on the wings.

26.    Part of the fuselage in which people sit.

27.    Hinged control surface attached to the tailplane trailing edge used to move the tail up and down.

Down

1.    The wheel or wheels found just under the nose. Nosewheels are steerable.

2.    Horizontal aerofoil mounted on the aircraft tail to provide longitudinal stability.

3.    Small aerofoils mounted more or less vertically, on the wing tips to help control airflow over the wing.

4.    The people who serve the passengers.

6.    The structure which attaches an engine to the wing.

9.    The window that the pilots look through.

12.    The wheels on which an aircraft rests while on the ground.

13.    The front of an aircraft.

14.    The covering of an aircraft’s structure. Be careful, the skin is not as robust as it looks and can be easily damaged by GSE.

15.    Where the cargo is stowed.

17.    A gas turbine engine which uses the jet exhaust to turn a propellor.

19.    Rotating blades with an aerofoil section. Driven by an engine to create thrust which is used to move an aircraft forward. Usually mounted in front of the emgine but sometimes behind the engine. Propellors spin very quickly so be careful when working near moving propellors.

20.    This produces the thrust to push an aircraft forward.

21.    Part of an aircraft in which people sit and cargo is stowed

24.    A control surface mounted on the wing leading edge. Slats allow an aircraft to fly at a higher angle of attack – with the nose up – than normal. Watch when aircraft land, how high the nose is compared to when is flies normally.

ANSWERS

Across

5.    FLAP—Movable control surface mounted inboard on the wing trailing edge – the back end of the wing, – which can be lowered partially to increase lift or fully to increase drag and slow the aircraft down.

7.    AIRSTAIRS—Some smaller aircraft usually used for short distance travel, have their own stairs built into the cabin door for the passengers to enter or leave the aircraft.

8.    COWLING—The fairing which encloses an engine

10.    WING—The long bits that stick out the fuselage, more or less, horizontally. In flight they generate the lift that enables an aircraft to fly.

11.    RUDDER—Movable control surface mounted on the fin. It is used to change the direction in which the aircraft is travelling.

14.    SEAT—What the people sit on.

16.    SPOILER—Devices mounted on the top of a wing to “spoil” the airflow across the wing to reduce lift. Alao called “lift dumpers.”

17.    TAIL—The end of an aircraft.

18.    GALLEY—The small room in which meals and drinks are prepared.

21.    FIN—Fixed vertical control surface mounted on the tail. The fin controls the direction inwhich the aircraft is travelling.

22.    TURBOFAN—A gas turbine engine in which some of the air is ducted past the turbine and added to the jet exhaust.

23.    MAIN GEAR—The large number of wheels mounted under the fuselage about where the wings joiin the fuselage.

25.    AILERON—Hinged control surface mounted on the wing trailing edge which is used to contol rolling movements. Found outboard (near the tips.) on the wings.

26.    CABIN—Part of the fuselage in which people sit.

27.    ELEVATOR—Hinged control surface attached to the tailplane trailing edge used to move the tail up and down.

Down

1.    NOSEWHEEL—The wheel or wheels found just under the nose. Nosewheels are steerable.

2.    TAILPLANE—Horizontal aerofoil mounted on the aircraft tail to provide longitudinal stability.

3.    WINGLET—Small aerofoils mounted more or less vertically, on the wing tips to help control airflow over the wing.

4.    CABIN CREW—The people who serve the passengers.

6.    PYLON—The structure which attaches an engine to the wing.

9.    WINDSCREEN—The window that the pilots look through.

12.    UNDERCARRIAGE—The wheels on which an aircraft rests while on the ground.

13.    NOSE—The front of an aircraft.

14.    SKIN—The covering of an aircraft’s structure. Be careful, the skin is not as robust as it looks and can be easily damaged by GSE.

15.    HOLD—Where the cargo is stowed.

17.    TURBOPROP—A gas turbine engine which uses the jet exhaust to turn a propellor.

19.    PROPELLOR—Rotating blades with an aerofoil section. Driven by an engine to create thrust which is used to move an aircraft forward. Usually mounted in front of the emgine but sometimes behind the engine. Propellors spin very quickly so be careful when working near moving propellors.

20.    ENGINE—This produces the thrust to push an aircraft forward.

21.    FUSELAGE—Part of an aircraft in which people sit and cargo is stowed

24.    SLAT—A control surface mounted on the wing leading edge. Slats allow an aircraft to fly at a higher angle of attack – with the nose up – than normal. Watch when aircraft land, how high the nose is compared to when is flies normally.

See how accidents can happen to an aircraft

STATISTICAL PROCESS CONTROL CHARTS – BASIC ANALYSIS

WHAT DO YOU ALREADY KNOW?

Control limit

Point

Process shift

Reading

Mean

Trend line

Zone

Answers at the end of the lesson

WHAT YOU WILL LEARN

How to analyse Statistical Process Control Charts

TESTING  WHAT YOU HAVE LEARNED

At the end of the lesson, there is a short test for you to check your understanding of the topic. This is followed by a short test on to determine if you can apply what you have learned.

This is a brief introduction to Control Chart analysis. The subject is vast and, at higher levels, needs advanced statistical knowledge. What we have here is enough for you to get started and fix the really serious problems like the one in the picture which annoy your customers and cost you money.

Analysis of Statistical Process Control (SPC) charts is the interpretation of the process measurement patterns over a period.

You should have at least  25  measurements or readings before you start to analyse your chart otherwise you will probably get misleading data and take incorrect corrective action which won’t win you any friends and may cost your company money.

Ideally, we should have a chart with the following characteristics:

Most points are near the mean (average), 

A few points near the control limits,

No points are beyond the control limits. 

If a control chart does not present these characteristics, there is probably a special cause (some kind of problem) present. The common tests for determining if a problem is present are:

Any point outside a control limit (Rows 1 and 8)

The red point in row 8 is outside the upper control limit (UCL)

> UCL 8 X
Zone A+ 7 X
Zone B+ 6
Zone C+ 5 X X X
Zone C- 4 X
Zone B- 3 X
Zone A- 2 X
< LCL 1

Possible causes include:

A data entry error.

Measurement error,  like recording incorrect arrival times.  Some people may think that arrival time is when engines are stopped, others only when the aircraft becomes available  for ground handling to start.  If the airline wants a 30 minute turnaround, the difference becomes significant.

Congestion on the ramp.

GSE breakdowns.

 

Overcontrol

Fourteen points in a row, alternating up and down

> UCL 8
Zone A+ 7 X X
Zone B+ 6 X X
Zone C+ 5 X X X X
Zone C- 4 X X
Zone B- 3
Zone A- 2 X X
< LCL 1

This is a system effect caused by using two pieces of equipment or operators alternately. For example, you might have two toilet trucks and teams, and they take different times to do the same work. You need to do separate charts for each driver or unit.

 

Trends

Six consecutive points, increasing or decreasing. (Some authorities use seven points)

> UCL 8
Zone A+ 7 X X
Zone B+ 6 X
Zone C+ 5 X X
Zone C- 4 X X
Zone B- 3 X
Zone A- 2
< LCL 1

Look at points 2 to 8 and you will see definite trend upwards.

The cause of the Negative (worsening) trend must be determined and corrective action taken. The cause of the Positive (improving) trend should be determined so that the company can introduce the improved methods in other areas.

A Positive trend may be due to the following:

Better training.

Staff gaining experience.

A Negative trend may indicate the following:

Equipment breaking down more often.

Consistently missing budget targets.

 

Process Shifts

This means that the process has been changed in some way. The change may indicate either an improvement or degradation in the process. This may be due to improved methods or degradation due to:

Poor equipment maintenance,

Equipment age,

A change in the quantity and/or quality of staff training.

The loss of a major customer which affects income.

In the case of a time measurement, such as cargo from a bay to the cargo centre, the average time taken may have changed significantly due to, for example, route changes, increased congestion in the cargo area, etc.

Zones

To facilitate analysis, we divide control charts into zones.

Zone A falls between the second and third standard deviations.

Zone B falls between the first and second standard deviations.

Zone C is the area between the mean and the first standard deviation.

Zones apply to both sides of the chart – above and below the centre (mean or average) line.

The third standard deviation on each side of the mean is the Control Limit.

Zone chart example.

Eight successive points on one side of the mean. (Some authorities use seven.)

> UCL 8
Zone A+ 7 X X X X
Zone B+ 6 X X
Zone C+ 5 X X X
Zone C- 4 X
Zone B- 3 X
Zone A- 2
< LCL 1

Look at the last 8 points, they are all on the same side of the Mean (located between Zone C+ and Zone C-)

You may have introduced a new accounting system may work better or worse than the previous one so that invoices may be sent to customers earlier or later than before.

The airport may have changed the traffic rules which may cause all movement of GSE to tale longer than before.

You may have employed another technician in maintenance which may result in faster turnaround of maintenance jobs.

Data falsification. If you have a “Blame” culture you may be assured that falsification will happen. Some examples:

   Bags rarely or never late at carousel. 

   Invoices rarely or never sent late.

   Steps hardly ever  late.

 

Two out of three consecutive points on the same side of the mean in Zone A or beyond

> UCL 8
Zone A+ 7 X X X
Zone B+ 6 X
Zone C+ 5 X X X X X
Zone C- 4 X X
Zone B- 3
Zone A- 2
< LCL 1

Two of the last three points are in Zone A+

A data capture error.

Measurement error,  like recording incorrect arrival times.  Different people may think that arrival time is when engines are stopped, others only when the aircraft becomes available  for ground handling to start.  If the airline wants a 30 minute turnaround, the difference becomes significant.

Congestion on the ramp,

GSE breakdowns.

 

Four of five successive points on the same side of the mean in Zone B or beyond.

> UCL 8
Zone A+ 7 X X X
Zone B+ 6 X X
Zone C+ 5 X X X X
Zone C- 4 X X
Zone B- 3
Zone A- 2
< LCL 1

Look for:

New or badly maintained GSE.

Driver fatigue.

Process change.

8 or more consecutive points NOT in Zone C on both sides of the mean.

> UCL 8
Zone A+ 7 X X X X
Zone B+ 6 X X
Zone C+ 5 X      
Zone C- 4
Zone B- 3 X  X  X
Zone A- 2  X
< LCL 1

The last 8 points (measurements, or readings) on or around the Mean

You can only apply this test to X-Bar charts.

This may occur for the following reasons:

You are charting more than one process on the same chart or the same process at different times of the day Peaks versus Off-peaks.

The toilet truck example also applies here.

 

Stratification

15 or more points in Zone C above or below the mean.

> UCL 8
Zone A+ 7
Zone B+ 6
Zone C+ 5 X   X X      X  X  X
Zone C- 4  X    X      X  
Zone B- 3
Zone A- 2
< LCL 1

This test can be applied to X-Bar charts only.

This test indicates decreased process variability which is a good thing if the process meets or beats the Service Level Agreement (SLA) standards and a bad thing if the process generally misses the SLA standards.

Possible causes

Data falsification. If you have a “Blame” culture you may be assured that falsification will happen. Some examples:

   Bags never late at carousel. 

   Invoices never sent late.

   Steps never or always late.

Or;

You may have introduced new work methods or GSE and the process has improved but you have not recalculated the control limits.

Note: You may find false warnings about every 100 readings. Don’t let this worry you, it is quite normal, just fix the problems as they come up.

 

WHAT HAVE YOU  LEARNT?

Between which 2 rows is the Lower Control Limit?

Where is the Mean?

What is a process shift?

What is a Control Limit?

What is a Trend?

What may cause a point outside a control limit?

What can cause a run of fourteen points in a row, alternating up and down?

What can cause a trend?

What can cause 8 points on 1 side of the mean?

Why would we find two out of three consecutive points on the same side of the mean in Zone A or beyond?

What would you look for if you found this pattern in your chart: Four of five successive points on the same side of the mean in Zone B or beyond.

What may be the problem if you find 8 or more consecutive points NOT in Zone C on both sides of the mean.

15 or more points in Zone C above or below the mean may indicate what?

 

WHAT DO YOU ALREADY KNOW?

Control limit

Calculated limits beyond which a reading should not be found.  Generally calculated at 3 standard deviations from the mean

Point

A position on a chart which represents a reading or measurement, for example, the time taken for the first baggage to arrive at the baggage centre from an arrival.

Process shift

This means that the process like ground handling has improved or worsened .

Reading

A measurement taken of a process.

Mean

The average of a set of readings or measurement

Trend line

A line which shows the drift of a process either getting better or getting worse.

Zone

An area on chart differentiated by line representing standard deviations.

 

WHAT HAVE YOU LEARNT ANSWERS

Between which 2 rows is the Lower Control Limit?

Rows 1 and 2.

Where is the Mean?

In the centre of the chart.  Also known as the average.

What is a process shift?

This means that the process has been changed in some way.

What is a Control Limit?

A calculated value 3 standard deviations from the mean.  A chart will contain an Upper Control Limit (UCL) and a Lower Control Limit (LCL)

What is a Trend?

A run of 6 or 7 consecutive readings up or down.

What may cause a point outside a control limit?

A data entry error,

Measurement error,  like recording incorrect arrival times.  Some people may think that arrival time is when engines are stopped, others only when the aircraft becomes available  for ground handling to start.  If the airline wants a 30 minute turnaround, the difference becomes significant.

Congestion on the ramp,

GSE breakdowns.

What can cause a run of fourteen points in a row, alternating up and down?

This is a system effect caused by using two pieces of equipment or operators alternately. For example, you might have two toilet trucks and teams, and they take different times to do the same work. You need to do separate charts for each driver or unit.

What can cause a Trend?

A Positive trend may be due to the following:

Better training.

Staff gaining experience.

A Negative trend may indicate the following:

Equipment breaking down more often.

Consistently missing budget targets.

Process Shifts

This means that the process has been changed in some way. The change may indicate either an improvement or degradation in the process. This may be due to improved methods or degradation due to:

Poor equipment maintenance,

Equipment age,

A change in the quantity and/or quality of staff training.

The loss of a major customer which affects income.

In the case of a time measurement, such as cargo from a bay to the cargo centre, the average time taken may have changed significantly due to, for example, route changes, increased congestion in the cargo area, etc.

Eight successive points on one side of the mean

You may have introduced a new accounting system which may work better or worse than the previous one so that invoices may be sent to customers earlier or later than before.

The airport may have changed the traffic rules which may cause all movement of GSE to tale longer than before.

You may have employed another technician in maintenance which may result in faster turnaround of maintenance jobs.

Two out of three consecutive points on the same side of the mean in Zone A or beyond

New or badly maintained GSE,

Driver fatigue,

Process change.

Four of five successive points on the same side of the mean in Zone B or beyond.

New or badly maintained GSE,

Driver fatigue,

Process change

Data stratification

8 or more consecutive points NOT in Zone C on both sides of the mean.

You are charting more than one process on the same chart. The toilet truck example also applies here.

15 or more points in Zone C above or below the mean.

Falsification of measurement data.

You may have introduced new work methods or GSE and the process has improved but you have not recalculated the control limits.

Data falsification. If you have a “Blame” culture you may be assured that falsification will happen. Some examples:

   Bags never late at carousel. 

   Invoices never sent late.

   Steps never late.

APPLY YOUR KNOWLEDGE

If your Maintenance department was always on budget, slightly up or down every month where would this show up on an SPC chart?

You would see a run of 15 or more consecutive points in Zone C on both sides of the mean. 

More about Ground Handling quality management

737 CRASH AT MANCHESTER – THE EMERGENCY RESPONSE

CASE 209

Solution included

Synopsis

British Airtours Flight
28M was a charter flight from Manchester to Corfu which caught fire before take-off at Manchester, England, Airport, with the loss of 55 lives.

The aircraft, a Boeing 737–236,  carried 131 passengers and six crew. During take-off the flight crew heard a thud; and not knowing the cause aborted the take-off. Investigation found that the thud had been caused by an engine component failure. Parts of the engine were ejected from the engine and ruptured a fuel tank. Fire broke out. The captain ordered the evacuation of the passengers. 82 survived; most of the fatalities were due to smoke inhalation. In contrast to the crash at Sioux City (Case 306) fortune was not with the emergency services and passengers.

Learning objectives

To expose students to actual operational problems in airside emergency situation, and to illustrate both the application and the potential benefits of using tools like: Risk analysis, 5 Whys, 5WH1, Timeline creation, and Brainstorming in problem-solving.

NOTE: Most of the failures described in the case will have been eliminated soon after the accidents. What the student is interested in is the aftermath of the crash – how the aircraft broke up and if there was a fire or not and, most importantly, how it was handled by the Emergency Response teams.

Students should compare this accident with that of the Sioux City crash. (Case 309.)

Pedagogical Objectives

The teaching plan consists of three phases organized around student research (phase 1) and a set of discussion questions to develop each of the emergency responses (phase 2) in the case. After the actual emergency events are presented to students, they should be encouraged to review their proposed countermeasures to the airframe damage and the injuries sustained by the passengers and flight crew (phase 3.) Reports of the failure (available online) and in our, or any aircraft library, can be used to make the case more interesting. See under the References heading.

Keywords

Emergency management, ground handling, standard operating procedures, problem-solving and risk analysis, communications, safety.

Target audience    Anyone with an operational or academic interest in problem solving or failure analysis in Air Transport.

Study time        4 hours. – 2+ hours research, 2 hours class.

Level    Industry staff or, academically, when emergency management and risk appear in the study curriculum.

Prior knowledge    Failure Modes and Effects analysis – not absolutely necessary.

Aim    To illustrate the importance of following standard ground handling emergency procedures.

Length            17 pages including the solution.

Published by        Air Transport Research Institute. 24 February 2019

Data source/s        Published sources

Similar cases        074, 076, 155, 306

Similar cases, details

Emergency Services     (We have taken a broad definition of emergency services to include offsite emergency, for example, the local municipality.)

074    Air Transat emergency landing

076    Emergency manuals locked in cupboard

155    Tenerife crash – 2 B747’s

306    Sioux City crash

Resources available to students and lecturers

Air Transport Research Institute Lessons – Power Point format

EQA106        Risk Fundamentals

FAN145        Timelines

FAN325        5 Whys

FAN335        W5H1

RIS126        Risk analysis basic

RIS135        Failure modes and effects analysis fundamentals

Case209    737 fire at MAN

Air Transport Research Institute website

  1. Potential airside operations failure modes and effects analysis and solution effectiveness evaluation
  2. 5 Whys
  3. 5WH – Free form
  4. Creating a timeline in Excel

References

IATA Airport Handling Manual

Angels in the sky – highly recommended