“In order to prevent that pressure from becoming excessive, the pilot-operated relief valve (a valve located at the top of the pressurizer) opened. The valve should have closed when the pressure decreased by a certain amount, but it did not. Signals available to the operator failed to show that the valve was still open. As a result, cooling water poured out of the stuck-open valve and caused the core of the reactor to overheat”.
“As coolant flowed from the core through the pressurizer, the instruments available to reactor operators provided confusing information. There was no instrument that showed the level of coolant in the core. Instead, the operators judged the level of water in the core by the level in the pressurizer, and since it was high, they assumed that the core was properly covered with coolant. In addition, there was no clear signal that the pilot-operated relief valve was open. As a result, as alarms rang and warning lights flashed, the operators did not realize that the plant was experiencing a loss-of-coolant accident. They took a series of actions that made conditions worse by simply reducing the flow of coolant through the core”.
Main Problem (What went wrong?)
The accident was caused by the personnel error, interface designers and component failures. There are few major reasons that caused the accident were, the main feed water pumps were not fitted properly, and that prevented the steam generators from removing heat and then turbine and reactor automatically shut down as well.
Inductive reason
By looking at the summary of events, I have found out that the main feed water pumps stopped running and the reactor automatically shut down.
Abductive reasoning
There were more than one reason for this to happen, firstly the main water pumps stopped working and one of the main valve reactors stopped working due to electrical or mechanical failure.
Another main reason was that one of the engineers misread the message on the screen and that led to a dangerous loss of water coolant from the reactor core.
Solution (How it could have improved?)
This could have been prevented if they had professional design for the plant and all the compulsory equipments, like fire protection, piping systems, etc. More HCI should have been used, for example, human’s performance should have been improved as a critical part of plant safety. Don’t just rely on the system to do everything, without making any errors. They should have used people to control the plant system, after giving them all the training properly.
The reactors fuel should have been covered so the fuel wouldn’t get melted. They need to upgrade and strength the plant design equipments requirements. They need to identify the human performance as a critical part of plant safety and staffing requirements.
Strengths and weakness
After going through the incident, I have noticed few weaker points. TMI should have analyzed and prepared more plans before adjusting the system to look after the Nuclear Plants.
One of the main weaknesses was that they didn’t have a proper interface design, about how to tackle any difficulties that are likely to occur. The accident was accompanied by communications problems that led to conflicting information available to the people in charge.
They should have made the use of Humans more to look after the nuclear plants, because there is a chance that the computer system will fail at some point, but if they had used humans as well as the computer system for security then this entire incident could have been avoided. They also should have made sure that they had enough security and warning alarm systems to make operators aware of any danger.
They should have produced or installed some sort of system, which can allegedly turn the nuclear plant system off automatically as soon as the danger occurred. Improved instructions should have been updated to avoid the confusing signals that plagued operations during the accident.
They also should have made a team that analysis the plants every now and then and try to get any minor faults fixed as soon as they found out.
Ergonomic aspects
Ergonomic aspects are especially important in the design of complex, high-tech, or automated systems. A poorly designed cellular phone user-interface may not cause an accident, but it may well cause great frustration on the part of the consumer and result in a marketplace driven business failure. A poor interface design on industrial automated equipment, though, may result in decreased production and quality, or even a life threatening accident.
Three Mile Island nuclear plant accident is a perfect example of people over - trusting the computer system. In that accident control panel specified the main valve as working properly, and the control room operators trusted the system, and assumed that every thing was fine, but in reality the valve was not working as instructed, and it became the main reason for the power plant accident. The actual reason of the accident is a control system design error that provided inaccurate information to the operators.
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HCI Case study 2
The Swanwick Air Traffic Disaster
I will now do my 2nd case study on “The National Air Traffic Services (NATS) Swanwick”, this is Britain’s main control centre located in Hampshire. This case also had HCI problem that led to this disaster.
Summary of Events
“TENS of thousands of airline passengers across Europe suffered lengthy delays of up to seven hours yesterday after faults hit two major air traffic control centres.
More than 80 flights using airports around London were cancelled and thousands of others delayed due to software problems at Britain’s main control centre in Hampshire.
The disruption was compounded by computer faults at the main European air traffic co-ordination centre in Brussels, which affected services across the continent.
In the third computer fault to hit National Air Traffic Services (NATS) in two months, controllers at its Swanwick centre were forced to halve the number of aircraft movements for five hours from 6:30am.
The glitches are thought to have been caused following a routine monthly upgrade of the Swanwick computer system overnight on Thursday, which appeared to have gone to plan.
However, a spokeswoman for NATS said: "When the morning shift arrived, they found they could operate only about half the workstations.
"To safeguard our safety standards, this resulted in us reducing by half the number of aircraft coming into the system."
Main Problems
This is what one of the main workers had to say about the system.
“Controllers' screens were not clear enough to be safe, he said. The screens had green labels for planes the staff were working with, and white labels called "background tracks" for planes the operator was not talking to.
The controller said these background tracks were a "serious" problem, because they were not bright enough to be seen clearly. "A controller descending or climbing an aircraft with a green label may not see the white label in confliction with it." There's not enough contrast in my opinion to safely operate these screens."
From this persons statement I can tell that the system’s interface design was not very good. The contrast of the colour was not bright enough to be seen clearly, and the controllers were finding it difficult to control it. This is a serious issue that managers should have looked at, and sorted it out, but they didn’t.
Inductive reasoning
The main reason was that due to poor screen design; workers couldn’t see the screen clearly.
Abductive reasons
The main reasons were poor interface system, as the screens were not clear enough for the workers to analyze the system. Lack of staff support was another major factor for the system to collapse.
Solutions
It could have been avoided if they had a better computer interface design and more staff at the scene. At the time when the system did crash, they should have had some kind of alarm system when something goes wrong there should have been some alarm system to let the responsible people know.
The main weakness of the system was that they didn’t have a proper designed interface for users. They should have created brighter forms for the users so they didn’t get any troubles using them to control the air crafts. The screens had green labels for planes that staffs were working with. The background tracks were not bright enough to be seen clearly, which was the major problem for the staff.
3) Design a prototype form to a client specification and justify.
I have been asked to design a prototype form for a client’s specifications. There are different types of forms build for specific requirements. Forms are used to collect large amounts of information. It is also useful for surveys, login in details or to sign in. Forms are designed by companies to improve their business, to get the best possible opinions of people.
Feedback forms are normally designed by website owners to find out what users think of their website and how can they improve the website. Some times user doesn’t like to fill in the forms and this is because forms are too long, too many questions asked or they have to type in lot of information. Other reasons for user not filling the form can be because they are asked to give their email address, house address or name etc. Most of the time users don’t like to give their personal details to unknown companies.
Difficult or irrelevant questions can also destroy user’s interest in filling the forms. Useless information should not be inserted in forms or the information that doesn’t achieve goals.
Design Guidelines (How we should design forms)
To design web forms, user should follow these instructions to make sure the forms are designed properly and accurately.
- User should use the controls correctly, like check boxes and radio buttons.
- User should design a form that asks for information in logical order, like, personal information then other relevant information.
- User should try to ask for minimum and relevant information.
- User should make sure that a form is most suitable alternative for the task.
- User should also try to use minimum restrictive controls e.g. Radio buttons.
- User should make sure that same information is not asked twice.
- User should also test the forms at the end to make sure the information is accurate and useful.
Holiday booking form
I will make sure that my form is designed and includes all the required information for “Student Travel Inc” company. I will include the following data in my form.
- Name
- Age
- Email Address
- Gender
- Address
- Student – Part / Full Time
- Car Used (if any)
- Dates Required
- Last Holiday destination
- Disability / Any special needs
- Total annual holidays
- Submit Button
- Next Holiday destination
- Number of Independents
Storyboards
I will be designing my form according to (Jacob Neilson’s) Heuristics, and groping is one the main heuristics that should be considered during the design. I will group all the information in logical order for the form design. The following work will be the 1st part of my design form.
Personal Information (Form)
This part will include all the required personal information in the form. Now I will design another 2nd part of my form, which will include the holiday details.
Holiday Information (Form)
This is how I will put my information separate in to two parts. 1st part will ask for personal information and the 2nd part will ask for the holiday information.
Holiday Booking Form – (Personal Information)
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Surname – User will have to type his/her surname in space provided below.
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First Name – User will have to type his/her first name in space provided below.
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Address – User will have to type their address in logical order, in space provided below, which is standard three text boxes.
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Post Code – User will have to type in their correct post code in space provided below, which is text box.
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Gender – User will have to select their correct gender from two given options.
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Age – User can type his correct age in the space provided below.
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Student – User can select which kind of student he/she is, full or part time.
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Email Address – User will have to type in their existing email address in space provided below.
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Next – User will have to click on NEXT command button to proceed to next stage of the filling the form.
Holiday Booking Form – (Holiday Information)
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Last Holiday Destination – User will have to type in the name of last place they went on holiday.
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Next Holiday Destination – User will have to type in the nameof next possible destination they would like to visit.
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Number of Independents – User will have to type the number of people that are likely to go on holiday with him/her.
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Total Annual Holiday – User will have to type the number their annual holidays.
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Car Used – User will have to type in the name of the car that was used in their last holiday, (only if they went by car).
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Dates Required – User will have to choose the date they want to leave for holiday and the return date from holiday.
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Check Availability (Command Button) – User will have to click on this command button after choosing the leaving and return date of holiday.
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Dates Available – After user had clicked on the “CHECK AVAILABLITY” command button, system will display the dates that are available to go on holiday.
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Disability/Special Needs – User can type in any disabilities that he/she has or any special arrangements that are required to make by the company for him/her.
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Finish – User will have to click on “FINISH” command button after he/she finish completing the form. System will submit the information given by the user.
Evaluation (Heuristics)
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Required Information – Only important questions are asked in this form and user shouldn’t have any problems of filling in the form. Required information heuristic is defined in this form.
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Layout – This forms design has a very good layout and all the information is placed in efficient areas. Each label and input field is grouped by vertical proximity and the consistent alignment of both input fields and labels reduces eye movement and processing time. Users only need to move in one direction: down.
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Groupings – This form is designed in order to keep all the relevant information together at same place. For example, form asks user to type their name, then address and then choose the gender. It’s not like name is asked at the start of the form and address is asked at the end of the form.
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Contrast – This form has a good contrast with suitable font colour and size. Same font colour is used through out and consistent background colour.
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Not too long – This form is designed with simplicity and only relevant questions are asked, and all the questions are essential, so the user will surely not get annoyed with form being too long or boring.
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Simplicity – The form is very simple and all the questions are asked in Basic English. The form is not too flashy and long, it is kept as simple as possible by standard of knowledge.
Verification and Validation in HCI
It is very important for business companies to test the systems and validate and verify it. The development of user interfaces (UI) needs validation and verification of a set of required properties. Different kinds of properties are relevant to the human computer interaction (HCI) area. Not all of them may be checked using standard software engineering validation and verification tools. Indeed, a large part of properties is related to the user and to usability.
The two major V&V activities are reviews, including inspections and walkthroughs, and testing.
Role of v & v is very important in HCI, it is there to be used by the business organisations to minimize the errors occur in their systems. For example v & v system, should be used to make sure that user types his/her email address correctly. It is very rare that a human being can make same mistake twice. When a user is signing up for some website to become a member, system asks user to type their email address and password twice, to make sure that he/she is typing in the correct details. For Example;
1. Options | 2. Your Details | 3. Confirmation
Registration
Please provide the information below to signup for your Registration. Information marked with * is optional. All information can be updated after registration using the My Account section.
Login Details
Email Address
(Username for login)
Re-enter Email Address
Password
Re-enter Password
This is a screen shot from Liverpool website, where the system asks users to enter their email address and password twice. This process is done to make sure that user doesn’t make any mistakes while typing his/her email address or password, because that email address will be his/her login as well when he/she will want to log on to the website. User will also have to type in their password to gain access through their account that he/she will open with Liverpool FC. If the user types in one email address in the 1st text box and different in the other then system will let user know that your email address in invalid. This process doesn’t allow user to complete the form until he/she has typed in the correct email address and password. This process is called Validation and Verification.
Continued from v&v….
HCI
HCI is highly involved in this process as User (Human) inputs email address, Computer (System) processes the details to validate the email address, and Interaction in the process is Keyboard, which is used to type in the email address. All three components are important in v & v process. HCI (Humans, computers and interactions) rely on each other heavily, the whole system will fail if you try to start any business organization.
To make an email address or an account using your email address, user can use any forms of letters available of key board. For example, he can type in . He is allowed to use just letters, numbers or both of them, he can also use the _ or – to create an email address.
When a user is wants to create an account with a website like apple.com, user will have to choose a password and the password must contain letters and numbers only, you are not allowed to use signs, like -, etc.
This print screen shows apple website, you can see that they are asking new users that wish a open an account apple, to type their email address and new password. To make sure that user types in correct and sensible password. System is asking user to type in password and the password must be at least 6 characters and must only contain numbers and letters. This is a very good way to make sure user types in correct email address and password.
