Aspects of software safety

8.1 Aspects of software safety

The following are four of the most important aspects of software safety:

1. Software whose failure could damage hardware or equipment;

2. Software whose failure could hurt the business or enterprise;

3. Software whose failure could cause harm to the environment;

4. Software whose failure could cause harm to people.

Of course, some software might impact more that one aspect of safety, such as software involved in weapons systems, the medical field, or nuclear power generation.

8.1.1 Damaging hardware

An example of hardware damage might be damage caused when the software embedded in a generator fails to respond to a high temperature signal. This could permit the generator to overheat and fail in several ways (i.e., seizing the armature, catching fire, fracturing the housing, and so on). A more disastrous failure could be the meltdown of a nuclear power plant caused by an incorrect software action or response.

8.1.2 Business or enterprise damage

Software is often used to make important business decisions and actually run the business. Something as simple as a spreadsheet failure could result in management making a bad decision based on incorrect information. A retail store chain could lose track of its inventory and discover its automatic ordering system is ordering the wrong products. A warehouse management system could store products incorrectly and not be able to account for them when needed.

8.1.3 Environmental damage

The software monitoring an oil pipeline could fail to detect, or react incorrectly to the detection of, a leaking or burst section of the line. The resulting oil spill into the ground or sea could cause grave damage to the environment and, perhaps, the animals that inhabit it. Navigational software failure could cause an oil tanker to run aground and spill millions of gallons of crude oil into the sea.

8.1.4 Damage to humans

The safety-criticality of medical and air traffic control software is often recognized. For example, an air traffic control system failure could result in the collision of aircraft or the software controlling a morphine intravenous injection system could result in a patient's overdose.

However, with software being used in so many seemingly benign areas, we may overlook other hazards. For example, a faulty readout on an automobile speedometer could permit a driver to enter a curve too fast and crash. A computerized refrigeration temperature sensor could fail and permit the growth of dangerous bacteria in food.