2.1 Original impetus for single-pilot operations: Economic considerations

The original rationale for single-pilot operations was to reduce operating costs. However, Human Factors is not a cost: it can significantly contribute to improvements in operational efficiency [Reference Harris14]. Flight crew costs can represent up to 15.3% of operating costs depending upon aircraft type, sector length and how much activity is outsourced [15–17]. The pilots themselves represent almost 7% of operating costs. The airline industry is not a particularly profitable one: there are constant downward demands on pricing and unpredictable, fluctuating fuel costs coupled with a low operating margin. Over a decade ago, it was estimated that on a global basis, between 2000 and 2010 the aviation industry lost $47 billion [Reference Cleary18]. Pre-COVID, the International Air Transport Association (IATA) reported globally that post tax profits declined from $9.13 (per passenger) in 2016, to $7.69 the following year [19]. At the height of the COVID-19 pandemic, 2020 post-tax losses (per seat) in North America were $35.1 and in Europe were $34.5 [20]. As a result, IATA estimated that worldwide, airlines recorded a net loss of $126 billion in 2020, followed by a further $48 billion in the following year.

For US major inter-continental airlines each aircraft requires (on average) 12.55 pilots; US national airlines require 10.15 pilots per aircraft; US regional airlines, flying smaller aircraft require around 8.17. The annual financial reports of a major European low-cost operator suggest that each aircraft requires between 9 and 10 pilots, with the proportion of Captains and First Officers in the company marginally favouring the former [15]. Using the Boeing 737-300 as a baseline, it has been estimated that over a 25-year operational life, a single-pilot airliner would save between $1.25 and $4.38 million per aircraft [Reference Graham, Hopkins, Loeber and Trivedi21].

Parimal Kopardekar, concepts and technology development project manager at NASA Ames Research Center, noted that if single-pilot operations became commonplace, rather than threatening jobs (a concern for many pilot’s unions), it may have the opposite effect: The cost per passenger seat mile would decrease. ALPA themselves [11] estimate that removing one of the flight crew would cut around 4% from the total cost of a flight; Moehle and Clauss [Reference Moehle and Clauss22] assess the corresponding saving to be 2–3%. As a result of such economies, ticket prices would fall, yielding an increase in demand potentially requiring more pilots. A move to single-pilot operations could yield a growth in revenue, passenger numbers and an increase in feasible routes while simultaneously resulting in an unchanged demand (or an increase) in the number of pilots [Reference Comerford, Brandt, Lachter, Wu, Mogford, Battiste and Johnson23].

Other factors have now accelerated the need for the development of single crew airliners. Airbus anticipates that approximately 39,000 new aircraft will be required in the next 18 years, nearly doubling the current fleet size [24]. The corresponding Boeing estimate is even higher suggesting a demand for over 47,000 aircraft by 2041 [25]. However, commensurate with the increase in demand there is also an accelerating, global shortage of airline pilots. Estimates vary: In the US it is projected that there will be a shortage of 35,000–40,000 pilots by 2035 [Reference Duggar, Smith and Harrison26, Reference Higgins, Lovelace, Bjerke, Lounsberry, Lutte, Friedenzohn and Craig27], the majority of which will be borne by the regional carriers. Boeing expect that between 2021 and 2040, the world’s airlines will need 612,000 new pilots [28]: 130,000 new pilots will be required in North America: 115,000 in Europe and 250,000 in the China/Asia-Pacific region. Over 60% of these pilots will be needed to service airline expansion. FAA regulations, including changes in the required durations of rest between flights and the revised minimum flight experience for new hires have also contributed to this shortage [Reference Carey, Nicas and Pasztor29].

Tackling such shortfalls has usually been regarded as a recruitment and training issue. However, single-pilot, short-range airliners will provide a further option for reducing costs and the potential shortage of pilots. Furthermore, single-pilot aircraft will also provide greater flexibility in crew rostering [Reference Ligda, Fischer, Mosier, Matessa, Battiste, Johnson and Harris30, Reference Malik and Gollnick31], as issues in the appropriate pairing of crews will no longer be relevant, hence will also further reduce the size of the pilot pool required by an airline to satisfy crewing requirements (pairing Captains with appropriately qualified First Officers).

Nevertheless, any single-pilot airliner will require more personnel on the ground to support it. As will be discussed later, the size and functions of this ground support will depend upon the technological approach being employed. If a single-pilot aircraft is to result in significant cost savings, the ratio of personnel involved in the ground support component to those on the flight deck needs to be less than the current 1:1 ratio of First Officers to Captains. This will be a considerable challenge.

2.2 New opportunities

Recently a third rationale for the introduction of single-pilot regional operations has emerged. Short-range, electric commercial aircraft are being developed (e.g., the 19-seater Heart Aerospace ES-19, currently scheduled for service entry in 2026). Although the operating costs of such aircraft are anticipated to be considerably lower that their equivalent fossil-fuel powered contemporaries (anticipated fuel costs will be 50–75% of equivalent aircraft and maintenance costs 50% lower), the operating economics of such aircraft would benefit greatly from a reduction in flight deck crew, as currently the cost of two pilots must be amortised over just 19 seats. Significant weight reductions are also possible, especially if the flight deck is re-designed to accommodate a single pilot, relieving the aircraft of not only the weight of the pilot but also their seat, displays and associated controls, while simultaneously simplifying systems. In such an aircraft, this weight saving may translate into additional passengers/payload, extra batteries for greater range, or enhanced performance.

3.1 High level system architectures

In addition to the degree of automation/autonomy on board the single-pilot airliner, there are also higher-level considerations relating to the wider system architecture. These also impinge directly on the aircraft operating concept and the operational challenges faced by the single-pilot airliner system.

In NASA’s Single-Pilot Operations Technical Interchange Meeting [Reference Comerford, Brandt, Lachter, Wu, Mogford, Battiste and Johnson23] five basic configurations were discussed by participants. The option where a single pilot assumed the duties of the second pilot flying current technology aircraft was included as a baseline configuration; however, this option is now under active consideration for cruise phases of flight in the EASA eMCO concept of operation. Four other system configuration options were discussed:

• • Single pilot with automation replacing the second pilot: Similar in concept to the early approaches for the development of a single-pilot aircraft, which mostly utilised onboard technology in the form of ‘intelligent co-pilots’ or ‘cockpit assistants’. However, more capable automated/autonomous systems can now potentially be employed to this end. Even so, there will still remain a need for remote support of a single-piloted aircraft [Reference Bailey, Kramer, Kennedy, Stephens and Etherington55, Reference Schmid and Stanton56].

• • Single pilot with a ground-based team member replacing the second pilot: Neis, Klingauf and Schiefele [Reference Neis, Klingauf and Schiefele34] described four broad sub-categories of configuration using this approach:

  • ∘ Remote Pilot: This is the simplest concept. In this case the ground-based pilot has the capability of exerting control of the aircraft, supplementing or replacing the on-board pilot if required [Reference Matessa, Strybel, Vu, Battiste and Schnell57]. They are available to the pilot at any point during the flight (including pre-flight and shut down) and operate on a 1:1 basis (when needed) with the aircraft, but normally, the aircraft operates only under the control of the on-board pilot. A high degree of on-board automation will still be required in this configuration [Reference Stanton, Harris and Starr53].

  • ∘ Harbour Pilot: This is similar in concept to its marine equivalent. The Harbour Pilot possesses knowledge of a well-defined terminal area airspace, its procedures and operations, and provides real-time support to the single pilot during departures and arrivals [Reference Bilimoria, Johnson and Schutte47, Reference Matessa, Strybel, Vu, Battiste and Schnell57, Reference Koltz, Roberts, Sweet, Battiste, Cunningham, Battiste, Vu and Strybel58]. They may take control of the aircraft, if required. Schmid and Korn [Reference Schmid, Black, Neumann and Noy59, Reference Schmid and Korn60] proposed an architecture combining aspects of both the Remote Pilot and the Harbour Pilot concepts, where three separate ground-based operators are employed for support during departure, enroute and arrivals.

  • ∘ Hybrid Ground Operator: This ground-based operator undertakes dispatch and support to multiple nominal aircraft but provides dedicated 1:1 support to any aircraft during a non-normal or emergency situation. In this case, other aircraft being supported will be transferred to another operative. This SiPO concept was promoted in a number of simulation studies undertaken by NASA [Reference Bilimoria, Johnson and Schutte47, Reference Jay, Brandt, Lachter, Matessa, Sadler, Battiste and Harris61]. The 1:1 remote pilot configuration was evaluated in simulated in-flight diversion and emergency scenarios in the NASA SPO II trials [Reference Lachter, Brandt, Battiste, Ligda, Matessa and Johnson62]. These trials also involved several prototype collaboration tools to enhance pilot/ground-station communication and coordination. The analysis showed that it was feasible to manage successfully all the scenarios undertaken using a remote pilot.

  • ∘ Specialist Ground Operator: These fall into two further sub-categories – Ground Associates, who undertake normal dispatch and pilot support activities (‘Super Dispatchers’ [Reference Johnson63], and Ground Pilots who remain on stand-by to take over support during any non-normal or emergency situation. This could be further extended (the ‘Apollo 13 scenario’) where the Ground Pilot calls upon the collective expertise of other members of the distributed team in the AOCC (real time engineering support, support for in-flight re-routing, passenger handling and logistics, etc.).

• • Single pilot with onboard personnel serving as a back-up pilot: This option made provision for other personnel on the aircraft; for example cabin crew, to serve as an emergency second pilot but subsequently as not considered to be a viable development route [Reference Comerford, Brandt, Lachter, Wu, Mogford, Battiste and Johnson23, Reference Neis, Klingauf and Schiefele34].

All the above categories pose different research and development challenges and have operational and technical advantages and disadvantages. However, they have common underlying questions determining the viability of the single-crew concept. In particular, how many ground-based personnel will be required, and what will be their roles?

The ratio of ground support personnel to airborne pilots needs to be considerably greater than the current 1:1 ratio of Captains to First Officers to make such an aircraft economically viable. This is a factor that has yet to be determined but will be determined by the degree of on-board automation/autonomy and the operational concept.

Koltz et al. [Reference Koltz, Roberts, Sweet, Battiste, Cunningham, Battiste, Vu and Strybel58] suggested a Harbour Pilot could handle four-six consecutive approaches, assuming no off-normal situations. Harris [Reference Harris66], modelling departures and arrivals based upon the movements of a UK low-cost operator at a busy regional airport, estimated that at least six Harbour Pilots per shift would be required to service that particular airline at that airport. Brouquet [Reference Brouquet67] proposed a of 5:1 ratio of ground operators to pilots, potentially rising to 7:1, but did not specify the system configuration. However, as discussed later, these simple support ratios disguise a wider operational issue. Nevertheless, it can be concluded that the simple remote piloting option is unlikely to result in significant savings as the ratio of remote pilots to airborne pilots is likely to be close to unity [Reference Neis, Klingauf and Schiefele34, Reference Harris66].

3.2 Role of the pilot

The roles of the personnel in the system need to be established. The development of a single-pilot aircraft is a unique opportunity for a fundamental re-think of the role and function of the pilot. Organisationally rooted criteria for the allocation of functions [Reference Challenger, Clegg and Shepherd68] extend this issue beyond a simple technical consideration to the wider, socio-technical system. Over the years, the pilot’s task has changed considerably from being a ‘hands on throttle and stick’ flyer to that of a flight deck manager, overseeing both the human and automation resources on board the aircraft. Direct control is often limited to taxiing and take-off/initial climb. In many instances even the approach and landing phase is automated.

It is likely that this trend toward the pilot becoming an automation/mission manager will be further exacerbated in the advent of SiPO. Harris [9] suggested that the role of the pilot will be that of a flight manager on both a strategic and tactical level; a communicator with air traffic management, airline and other authorities; and a surveillance operative. In the case of more autonomous systems, the pilot will set high-level goals and the aircraft systems will determine the best way to achieve them [Reference Bilimoria, Johnson and Schutte47, Reference Sprengart, Neis and Schiefele69, Reference Mcdonald, Kay, Liston, Morrison, Ryan and Harris70]. The key role of the pilot will be to evaluate the progress of the flight and the automated functions within the operational context and be a ‘sense checker’. Automated/autonomous systems will provide error oversight and system monitoring. In the case of equipment malfunctions they will re-configure the aircraft as required and evaluate the implications for the flight; however, the pilot will still be required when a flexible decision maker is needed in response to unusual situations. The more obvious instances of this can be observed in the manner in which the crew managed potentially catastrophic, highly unseen in-flight emergencies, such as the multiple failures in Qantas flight QF32 or US Airways flight 1549 [71, 72]. However, less obvious instances include flight re-planning where facilities become unavailable at short notice while at a destination airport or completely unforeseen in-flight occurrences, such as the sudden closure of all US airspace on 11 September 2001. The goal of the pilot-centric design of a single-pilot airliner is to keep the crewmember at the hub of the decision-making process with them being the ultimate authority [Reference Mcdonald, Kay, Liston, Morrison, Ryan and Harris70, Reference Schutte and Harris73, Reference Schutte74]. Sprengart et al. [Reference Sprengart, Neis and Schiefele69] go as far as to suggest that this change in role should be reflected in a change in the title of the human operator on board the aircraft, from ‘pilot’ to ‘mission manager’. However, the skill set required to manage a single-crew aircraft will not be the same as that currently required to manage a modern airliner, which has implications for the selection and training of pilots.

5.1 Safety

The single-pilot aircraft is just the airborne component in a wider system. Focus has naturally been on the aircraft and aircrew but under SiPO, safety issues extend well beyond this component to all aspects of the ground-based aspect of the operation.

Human-factors considerations such as workload, situation awareness and error are products of complex, inter-related systemic factors such as the number and difficulty of the tasks to be performed in the time available; training and experience; the usability of the flight deck equipment; interactions with the flight task and other stressors [Reference Harris85]. In SiPO, workload and situation awareness will also need to be considered as part of a distributed, socio-technical system [Reference Stanton, Stewart, Baber, Harris, Houghton, McMaster, Salmon, Hoyle, Walker, Young, Linsell and Dymott86]. Contemporary models of Distributed Situation Awareness [DSA] have suggested that it resides in both human and non-human elements right across a system, not just in the pilot [Reference Stanton, Stewart, Baber, Harris, Houghton, McMaster, Salmon, Hoyle, Walker, Young, Linsell and Dymott86–Reference Harris88].

The potential for increased workload (and specifically instances of workload peaks) has been identified as a safety concern for SiPO [11–13] and was recognised as a hazard in the operation of SJs [Reference Burian, Pruchnicki, Rogers, Christopher, Williams, Silverman, Drechsler, Mead, Hackworth and Runnels89] as was the removal of the second pilot (Pilot Monitoring) in their roles as an error checker and as a counter to pilot incapacitation. Using the harbour pilot configuration [Reference Bilimoria, Johnson and Schutte47, Reference Matessa, Strybel, Vu, Battiste and Schnell57, Reference Koltz, Roberts, Sweet, Battiste, Cunningham, Battiste, Vu and Strybel58] a number of simulated flight trials showed that flight deck workload was within acceptable bounds and situation awareness was high. Harbour pilot workload was low [Reference Koltz, Roberts, Sweet, Battiste, Cunningham, Battiste, Vu and Strybel58]. Performance was maintained in a variety of different approach and weather scenarios. However, the resilience of a single-pilot airliner system was found to be inferior to the current two-pilot solution if there was not ground-based support in high workload, non-normal and emergency situations [Reference Bailey, Kramer, Kennedy, Stephens and Etherington55, Reference Schmid and Stanton56, Reference Harris and Harris64, Reference Revell, Allison, Sears and Stanton65].

There is a workload ‘cost’ associated with the management of flight deck crew; the Captain’s role in promoting communication, coordination and cooperation has a workload overhead associated with it [Reference Stanton, Harris and Starr53]. Doubling the number of pilots does not half the workload (and vice versa) but is does provide a workload margin. Modern flight decks are also already certificated to be flown by a single pilot in an emergency (FAR/CS 25.1523). SiPO simulated approach and landing trials in an Airbus A320 did not impose significantly higher workload on the pilots during normal operations but did impose greater workload in turbulent conditions and during abnormal operations. Error rates also increased in these situations [Reference Faulhaber90]. However, workload management can be trained [Reference Burian, Pruchnicki, Rogers, Christopher, Williams, Silverman, Drechsler, Mead, Hackworth and Runnels89, 91].

However, the second pilot can also introduce errors on the flight deck and their overall effectiveness as an ‘error checker’ has also been questioned [Reference Thomas92]. Moehle and Clauss [Reference Moehle and Clauss22] describe several instances where interactions between multiple crew members contributed to the subsequent accident. Poor CRM has been ascribed as a contributory factor in 23% of fatal jet aircraft accidents [93]. Omission or inappropriate actions were implicated in 39% of accidents and incorrect application or a deliberate non-adherence to procedures was implicated in a further 13%. Becoming ‘low and slow’ was a factor in 12% of accidents, and poor positional awareness was identified as a causal factor in a further 27% of cases. These all imply a failure to cross monitor the flying pilot. Nevertheless, these accident data also fail to show the number of instances where the second pilot trapped an error: this is unknown and unknowable, and may occur several times on each flight. Put simply, this is good CRM. Nevertheless, observational data from routine commercial flights reported 47.2% of Captains’ errors involved intentional non-compliance with Standard Operating Procedures (SOPs) and regulations; a further 38.5% were unintentional non-compliance [Reference Stewart and Harris80]. It was also reported that more than half of all errors went undetected by one or both pilots. A similar study in the US [Reference Dismukes and Berman94] observed an average of 3.2 checklist errors per flight: 5.2 errors in the application of primary procedures, and 6.5 errors in monitoring. Error rates were more related to the number of procedures required rather than flight duration. It was noted that only 18% of these deviations were subsequently trapped and corrected. However, it was also observed that 89% of these errors had no discernible negative outcome and that the overall rate was probably only in the region of one percent. Error checking and pilot monitoring will be essential automated functions to incorporate into SiPO flight decks. To ensure safe and efficient coordination of ground and air resources, new forms of CRM will be required (Single Pilot Resource Management [84, 91]) to address issues such as risk management, automation management, task and workload management, and maintaining situational awareness.

A common concern for SiPO is associated with the incapacitation, impairment or ultimately death of the pilot. Fortunately, such instances are extremely rare. Between 1993 and 1998 there were only 39 instances of in-flight incapacitation and 11 instances of impairment in US airline pilots [Reference Dejohn, Wolbrink and Larcher95]. The overall rate of in-flight events encompassing both categories was 0.058 per 100,000 flight hours, and the probability that subsequently such an event would result in an accident was estimated to be 0.04. Flight safety was only seriously impacted in seven cases, resulting in two non-fatal accidents. The Australian Transport Safety Bureau’s (ATSB’s) accident and incident database contained 98 occurrences of pilot incapacitation between January 1975 and April 2006 [Reference Newman96]. These events resulted in 82 incidents and 16 accidents. All ten fatal accidents involved single-pilot operations but were concerned mostly with private or business operations. It was noted that medical standards for professional pilots were more stringent than those for commercial pilots. In the only fatal accident that involved a charter operation, incapacitation occurred as a result of hypoxia, not any pre-existing medical condition. A later study of UK commercial pilots suggested a much higher incapacitation rate than that reported in the US with the estimate of the annual in-flight rate to be 0.25% [Reference Evans and Radcliffe97]. However, these data were not weighted by flight hour and the rate was expressed as the proportion of all UK pilots, irrespective of their flight hours.

All single-pilot aircraft will require ground support, even the more autonomous versions. There are potential safety benefits which accrue from the ability to assume control of the aircraft from a ground station. Revell et al. [Reference Revell, Allison, Sears and Stanton65] describe the system redundancy afforded by the ground operator in the case of hypoxia (cf. the Helios Airways accident, 2005 where the pilots became incapacitated as a result of hypoxia following a cabin pressurisation incident). SiPO pilots will need to be continually monitored to support workload offloading [Reference Liu, Gardi, Ramasamy, Lim and Sabatini48–Reference Jun, Lei, Jia and Xudong51] but this also has the benefit of supporting intervention from the ground in the case of incapacitation. Similar potential benefits also accrue in the instances of in-flight fire. In the case of a scenario such as the Germanwings pilot homicide/suicide, it can be argued that the ability to override the aircraft from the ground (or for the on-board autonomy to intervene) provides an additional layer of safety, rather than degrading safety [Reference Schmid and Stanton56]. Ultra-secure, high-speed data links will be required though to enable these benefits and assure a high degree of cyber-security.

5.2 Regulation

The current regulatory position is that SiPO for large commercial aircraft are not permitted. The regulatory challenges are manifold, but without regulation in place allowing for single-pilot commercial operations, there is no viable future for the concept. Moehle and Clauss [Reference Moehle and Clauss22] argue that the real challenge lies in convincing regulators and the public that commercial operations can be performed as safely with a single pilot as with two.

The future certification of a single crew airliner will pose considerable challenges. International agreement will be required to develop new aircraft and operating certification requirements (the requirement for two pilots is principally an operating regulation, e.g. 14 CFR Part 121.385: Composition of Flight Crew). Furthermore, the formulation of a new certification approach will be necessary to demonstrate the safety of the aircraft and its operation. A great deal of the certification and regulatory challenges will necessarily be directed towards the Human Factors aspects. A full discussion of the related challenges is outwith the bounds of this paper, but SiPO will impinge on most aspects of the regulatory system, from design and certification, to operations and training, including approval of simulation facilities. All are inter-related. Current regulations (for example flight time limitations) may need to be modified if it is found that SiPO is more fatiguing than multi-crew operations, even though sectors are likely to be quite short. New areas of regulation and certification will also be required for the non-airborne components of the system.

Existing certification methods are limited in their capability to address the safety issues and evaluate the range of solutions that are likely to be implemented in SiPO. Current certification approaches regard the aircraft as a standalone component. However, the single-pilot aircraft is just one component in a wider operating system, which will also include ground-based components that will have a direct effect on the safety and efficiency of operations. A new regulatory approach to safety assurance will be required. In the same manner as the safety assurance of UASs, the airborne component cannot be considered alone [98, 99]. One proposed pathway to certification incrementally changes the focus of control from the pilot to the automated systems/autonomy in the aircraft in the event of a pilot becoming overloaded or incapacitated [Reference Lim, Bassien-Capsa, Ramasamy, Liu and Sabatini100]. From a certification perspective this has the benefit of keeping all the systems to be assessed in the aircraft itself which is commensurate with the current aircraft certification ethos (c.f. Harris [Reference Harris101] who suggested that control should transfer to the ground). It also has benefits, providing less reliance on high-integrity, high-speed data links required by the distributed crewing design approach. However, it does not preclude ground-based systems from being incorporated into any safety assessment as an adjunct.

From a Human Factors perspective, a coherent link between aircraft design, training and operations is required to enhance both safety and efficiency. These issues are complex, highly inter-related and multifaceted. Further regulatory initiatives will be required which extend beyond the aircraft. Operating a single-pilot commercial aircraft will require a re-distribution of tasks between the air and ground, and the pilot and machine. These will not just simply be flying tasks, but also flight management activities, coordination and wider personnel management duties. Control and surveillance data will be swapped in real time between the air and ground components. As a result, a safety case approach will probably be required to supplement the certification of the aircraft component itself [98, 99, Reference Harris101]. Such a ‘top-down’ approach focuses on critical issues that affect specific safety targets, addressing complex interactions between the human, non-human, air and ground-based components in the system. Hazards are addressed by a combination of design and operational requirements and are constrained by the need to comply with a code of requirements for individual aspects of the system (cf. those in the certification requirements in FAR/CS Part 25). They are not prescriptive in the manner by which safety is demonstrated. The objective is to demonstrate that systems meet a defined safety goal. This approach is used for the safety assessment of UASs [98, 99]. Furthermore, the basis for safety cases is being used by airlines as part of their Safety Management processes. In the case of SiPO their root causes and amelioration will extend beyond the flight deck to the ground support elements.

As an example, under SiPO, ground-based personnel, such as Dispatchers, will now perform a safety-critical role in the operation of the aircraft. In the US, the FAA certificates Ground Dispatchers, requiring formal training and testing. The FAA Aircraft Dispatcher Certificate already requires knowledge of subjects such as meteorology; interpreting weather charts and forecasts; interpretation and usage of NOTAMs; air navigation in IMC; ATC procedures; aircraft performance, weight and balance calculations; aerodynamics; Human Factors, aeronautical decision-making and CRM. There is no such equivalent qualification in Europe. In the case of SiPO the function of the Dispatcher will need to be extended. In Europe it is likely that formal qualifications (and recurrent testing) will need to be developed. As another instance, consider the single-pilot airliner flown using the Harbour Pilot concept of operation. To become a Maritime Harbour pilot serving a major port, seafarers are usually required to hold an International Maritime Organisation Master’s qualification and have served as Captain or Chief Officer on a merchant ship. In the UK the pilot has the legal conduct of the ship in their designated waters and is responsible for directing and executing a passage plan, and directing the speed and course of the vessel. Similar knowledge and qualifications will be required of an airline Harbour Pilot; however, it is not clear if such a role is aircraft type-specific.

A regulatory challenge will be to provide a system-wide safety assurance approach for SiPO while maintaining the safety advances made using the current certification systems. Harris [Reference Harris101] has described one potential method to such a system-wide certification that integrates the current ‘system-by-system’ certification approach with a safety case-based methodology.

5.3 Regulatory capture?

Regulatory capture is the process by which influential institutions manipulate regulatory agencies to their benefit. The FAA was accused of failing to provide independent oversight and regulation in the cases of the Boeing 737 MAX, specifically the Maneuvring Characteristics Augmentation System (MCAS) which was designed to prevent an excessive angle-of-attack developing [102]. However, SiPO will be dependent upon wider, international regulatory changes and agreement.

Regulatory change needs to keep pace with that of technology development, but the question arises if single-pilot aircraft are simply a financial and operational sinecure to address the issues described in the opening section at the expense of safety. However, the development of SiPO technologies and operational concepts can also drive the development of new flight deck equipment for multi-crew aircraft and encourage safety to be examined in a more integrated fashion, adopting a holistic air/ground perspective [7, Reference Harris101], which is beneficial for current operations. Reductions in flight crew complement in the past have been accompanied with step changes in technology (e.g. two-crew aircraft and the introduction of first generation, ‘glass cockpit’ aircraft using flight management systems [Reference Mclucas, Drinkwater and Leaf103]. The net result has usually been a decrease in the accident rate [104].

Regulators are adopting a pro-active approach to the safety analysis of potential SiPO [4], however this is driven by manufacturers developing the technology and airline interest. Searching for economy by reduction in personnel numbers is nothing new and is fundamental to many human-factors related activities [Reference Huddlestone and Harris105]. Where this legitimate operational strategy becomes the more questionable practice of regulatory capture is moot, but the latter certainly need to be recognised if it is to be avoided.