Aviation Safety and Security

Utilizing Technology to Prevent Aircraft Fatality

Stephen J Wright

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000396331
• Edition: 1
• Topic: Computer Science
• Subtopic: Human-Computer Interaction
• Index: Computer Science

This book focuses on ways to better manage and prevent aircraft-based homicide events while in flight using alternate technology to replace the Cockpit Voice Recorder (CVR) and/or Digital Flight Data Recorder (DFDR) functions. While these events are infrequent, the implementation of real-time predictive maintenance allows aircraft operators to better manage both scheduled and unscheduled maintenance events. Aviation Safety and Security: Utilizing Technology to Prevent Aircraft Fatality explores historical events of in-flight homicide and includes relevant accident case study excerpts from the National Transportation Safety Board (NTSB) and Air Accidents Investigation Branch (AAIB).

FEATURES

• Explores historical events of in-flight homicide and offers solutions for ways to mitigate risk

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• Explains how alternate technologies can be implemented to address in-flight safety issues

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• Demonstrates that metrics for change are not solely for safety but also for financial savings for aircraft operation

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• Includes relevant accident case study excerpts from the NTSB and AAIB

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• Expresses the need for real-time predictive maintenance

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Stephen J Wright is an academic Professor at the faculty of Engineering and Natural Sciences at Tampere University, Finland, specializing in aviation, aeronautical engineering, and aircraft systems.

1

Introduction

Regardless of where a passenger may travel from and to, travelling via commercial airlines is a safe and secure means to allow us to get from A to B in a relatively short time frame. Commercial aircraft travel is very different from surface transportation options, such as travelling by train, coach/bus/car or even a ship.

Yet commercial aviation has always been operated very differently from other transportation types. The security aspects (at the airport) are very different for travellers, staff and operators compared to the surface transportation means. But some of the biggest successes from changes and improvements have been driven by the aviation sector's willingness to ‘learn’ from its errors. If we consider an Airbus A350, full of fuel, cargo and passengers on a long haul flight, the A350’s take-off run will involve it speeding down the runway at velocities greater than 155 knots (kts), which is approximately 180 miles per hour or 290 kilometres per hour. The speeds during landing with full flaps reach similar numbers. The purpose of bringing these values to the attention of the reader are to demonstrate the high speeds associated with take-off and landing, and assuming the aircraft (i.e. A350-1000 MTOM) is close to its maximum take-off mass, it will be weighing is 310,000 kg. Put into context, aircraft have always been vehicles that are very lightweight (and strong) but 300 tonnes of mass travelling at 180 mph is some achievement, and risk. The aircraft is not only a feat of achievement in terms of design but also maintenance, and yet the ways the airlines and Air Traffic Controllers (ATC) control and operate these commercial aircraft has barely changed since the significant growth of aviation after the Second World War. When problems have occurred during the take-off run, the flight or the approach/landing phase, this combination of high speeds and lightweight structures has been aviation’s ‘Achilles heel’ in terms of the accident rate, survivability and so forth. With those basic facts established, the aviation business has always carefully reviewed past experiences, evaluated how things ‘went wrong’ in forensic detail and made the necessary changes to prevent the same event from happening again.

The governments around the world very carefully regulate the whole aviation sector. The governments use the form of a National Aviation Authority (NAA) of a given country (e.g. Federal Aviation Administration, USA, Civil Aviation Authority, UK, etc.). These basic rules and methods to organise and regulate air transportation date back to the Chicago Convention, December 1944, where 52 separate countries or states agreed how aircraft, airspace and specific events would be controlled and organised. The convention signing later leads to the formation of the specialist United Nations organisation, the International Civil Aviation Organisation (ICAO). In general terms, the NAA has the responsibility for the airlines that are operating from their country, the design of any an aircraft originating from this country, the licensing and examination of pilots, engineers, ATC, etc….

Thus, as aircraft have developed, so have the rules and regulations that surround all aspects of them: these rules are procedures evolving at a similar rate to that of the aircraft, with the overall objective to improve safety. For the most part, this professional attitude of openness, review and continuous improvement has made commercial aviation the safest means of transportation in Europe and North America, which the travelling public has taken for granted in recent years.

The standards that are currently imposed for travellers regarding aircraft cabin security have evolved over the years, often as a result of hostile, and sometimes homicidal acts. While the security aspects for commercial aviation and travellers are so different from other surface transportation means, the justification for the higher levels of screening/profiling and checks is based on the historical events.

This book will explore the various aspects of commercial aviation’s safety and security to evaluate significant past experiences (that are mostly in the public domain), to explain how some of the technical systems function in-flight, certain events that have resulted in the loss of the aircraft (due to deliberate acts) and lastly to explore how new state of the art technologies can be used to improve the high levels of safety that we, the travelling public, all take for granted. By understanding these aspects, one can better understand how the industry has evolved with successive events, the various incremental steps taken to stop ‘hostile acts’ from occurring inside a commercial aircraft.

Note: This book will not address (in forensic detail) the ‘landside to airside’ security screening processes carried out by security staff at airports. While the evolution of the screening is briefly explained, the technologies behind the latest full body (millimetre wave back scatter) passenger imaging (see Figure 1.1) or the latest conveyor based ‘X-ray’ scanner for bags/coats are not included. This is because the technologies underpinning these developments are rapidly changing, in terms of the computing algorithms that evaluate the sampled data. These predict whether the liquid in the bag is nail varnish remover (a formulation containing acetone), or a deadly liquid cocktail containing concentrated hydrogen peroxide that would lead to a detection signal and alert staff to conduct further testing. Furthermore, the current capabilities of the ‘landside to airside’ security screening measures are so rigorous, combined with the extensive use of computing calculations to perform the repetitive tasks to provide an accurate detection, the probability of an individual being able to bring a prohibited item onto an aircraft is now very small indeed. The human operators that previously needed to view the ‘X-ray’ screens were never able to maintain absolute focus, because fatigue and repetition affect the security operators’ ability to analyse the silhouette images and identify prohibited items. As much of the travelling passengers are also recorded during this in-depth screening, the potential that a traveller could avoid/obstruct or interfere with the security screening process and then be able to board a commercial flight is considered even less probable: this is because, should a failure in the screening process be detected (and be captured from the video data), it is possible (and for certain flights normal practice) for the ‘airside passengers’ to be rescreened for a second time, to establish an additional layer of certainty that all the passengers are free from prohibited articles (sharp objects, guns, etc.).

Figure 1.1
Example of a modern full-body (millimetre wave back scatter) image showing hidden weapons concealed in clothing. (L Kaufman.)

Chapter 2 discusses some of the more pertinent events associated with security aspects and failings in aviation. The context of why aircraft have been targeted over the years by successive hostile persons (insurgents/ terrorists and criminals) is explained, including the first recorded pilot homicide event.

Chapter 3 explains the background associated with Flight Data Recorders and Cockpit Voice Recorders. While these devices have their roots firmly established in early aviation, the use of wide spread data recorders became popular in response to unexplained accidents. The development of recorders is explained, from continuous magnetic media-based devices to today’s modern solid-state recorders that have proved so vital in explaining why so many aircraft have been lost.

Chapter 4 gives the reader a technical understanding of two very important systems to explain Flight Controls and Environmental Control Systems. The importance of these systems cannot be underrated, as all modern aircraft are fitted with a Flight Management Computer (FMC) to define the routing of the flight. After take-off, the FMC uses the various data inputs from the aircrafts’ navigation systems to fly the aircraft as per the routing when the autopilot is engaged. The air-conditioning system forms are the critical components that are included in the Environmental Control System (ECS). The ECS is necessary, because commercial aircraft fly in atmospheric conditions that do not support life in ambient conditions. The solution used is to take clean high-temperature compressed air from the engines (or for B787 an electric supercharger motor) and to pass this hot air into a device known as an air-conditioning pack. The pack allows for hot air to be piped into the aircraft in-flight, because the temperature outside during the cruise is likely to be below −57°C/−70°F. To help human respiration, the aircrafts’ cabin is also pressurised using this continuous hot air flow, because atmospheric pressure (around 1 atmosphere/ 101,325 Pa/14.7 psi) is required to allow our lungs to exchange oxygen gas for carbon dioxide gas. If the cabin pressure falls, then the gas exchange in the lungs drops resulting in incapacitation (hypoxia), and if not remedied, death. The level of pressurisation is controlled by the use of two or three gas outflow valves fitted into the skin of the aircraft. If the aircraft senses that the pressure inside the cabin is too high, the computer controller opens the valves a little to release some extra pressure. The use of the ECS is explained in the same level of detail given to pilots and engineers, because this life support has implications in certain security events that will be discussed in Chapter 8.

Chapter 5 introduces how the aircraft maintenance management philosophy has developed. The overall approved maintenance planning is explained, the differences between the aircrafts’ scheduled and unscheduled maintenance activities and the legal implications for these unscheduled maintenance defects that are deferred by the engineering operation to be repaired or resolved at a later time. Reliability in general terms is explained, because of the changes in the maintenance philosophy that have evolved since the Second World War. The financial gains that are attributed to an effective maintenance strategy to an airline are presented, because if an aircraft cannot fly due to technical reasons, this will cause an operator to lose revenue – thus the management strategy has very significant financial implications for the airlines.

The sources of the aircraft systems’ performance data are explained, including how the old multiple-page carbon paper-based systems that were popular for many years were superseded by more modern technology. The real-time delays encountered between the engineering technical paper log being filled in and the time when the data is entered into a maintenance IT system are explored. New sources of data are included, including where these new sources are located on the aircraft. The methods for the engineering departments to use engineers with portable data storage devices that can interface with the aircraft’s digital flight data recorder to download the data and subsequently be uploaded to a maintenance planning server are included. Likewise, being able to review some ‘live’ data from an aircraft’s system when the plane is operating is included, following the introduction of the Aircraft Communication Addressing and Reporting System (ACARS). Other more up to date systems are cited, including the use of a ground-based Wi-Fi network fitted at the airlines home-base (i.e. brouters) or the engine manufacturer’s inclusion of a data communication module (3G mobile phone based) on the engine’s Full Authority Digital Engine Control (FADEC) module, to transmit the leased engine’s performance trends (from the FADEC’s data storage) back to the engine manufacturer.

The theory behind some of the predictive maintenance is included, to give the reader an appreciation that a ‘learning mathematical system’ is used by the likes of Rolls Royce to predict acceptable or non-acceptable performances, and how the software optimises to maintenance, i.e. when to change components or whole engine modules.

Major aircraft manufacturers have also worked closely with data analytic organisations to provide a subscription-based maintenance management service: Airbus’s Skywise is used as an example, yet the data from the DFDRs still require an engineer with a laptop to download the terrabytes of data (from the week’s operation) that need to be uploaded to a server.

The general theme and driving principle for all maintenance management systems is to optimise maintenance activities, to keep the aircraft flying for longer and to estimate from historic data when to change components. The financial gains using these technologies are very significant!

Chapter 6 explores the evolution of the aviation sectors’ ability to learn from its mistakes (from historical events). Previous mistakes by pilots were simply explained as ‘pilot error’ yet the recurring historical crashes due to such pilot errors did not adequately explain why these highly trained professional pilots were behaving this way. After the 1972 Staines crash (a town very close to London Heathrow Airport), an accident investigator used his knowledge of the event and conceived the ‘SHEL model’ which explained the interactions between the pilot(s) and four other factors. The model was later surpassed by the ‘Error chain’ and the differences between these two models are explored. The third more recent human error model, known as the ‘Swiss Cheese model’, is explained, and the explanation as to why this model is so important to explain (Human Factors) deviations from intended performance is presented. Lastly, the overall Safety Management Systems of airlines discusses the legal requirements, and how these systems required the upper management to produce documentation specifying their corporate culpability should a significant failure occur. The general theme of the Human Factors concept is employees do not usually carry out reckless acts, rather they go to work to be productive, to do ...