Airbus vs Boeing Differences in Design Philosophy

Airbus vs Boeing

The Differences in Design Philosophy

Boeing versus Airbus – What are the differences?

At first glance, the design of the flight decks for Airbus and Boeing aircraft which are currently in production are visually quite similar. The screens, thrust levers, and various controls and levers are located in similar positions as can be seen when comparing an Airbus 320-200 and Boeing 737-800 flight deck in images below.

A320 Flight Deck

B737 Flight Deck

Automation Philosophies

Much of the similarities, both in terms of anthropometric design and automation, are mandated by the certification requirements set out by EASA and the FAA in CS/FAR-25. This mandates much of what must be visible to the flight crew, and its respective distance or angle from the Eye Datum Point for certain instruments (EASA 2020).

It could be observed that the significant visual difference between the design of the two flight decks is the inclusion of a Control Yoke on the Boeing aircraft, as opposed to the Side Stick found on the Airbus. Behind these two design differences there is a fundamental difference in the automation philosophy between the two manufactures.

Both manufactures have previously described their philosophy with regards to aircraft design and automation.

Whilst both manufactures share the philosophy that the pilots are ultimately responsible for the safe operation of the aircraft, Airbus has stated that “Automation should allow the operator to use the safe flight envelope to its full extent…” (Spitzer, Ferrell 2015: 224) (Airbus 2017: 6). This philosophy is incorporated into the automation design through Airbus’s flight control laws. In Normal and Alternate Law, the flight crew are able to manipulate the flight controls but are unable to make any input which would result in the aircraft operating outside a pre-defined set of parameters (Ibsen 2009: 343). The result is that the flight crew do therefore not have complete authority over the aircraft as certain flight envelope protections are in place to ensure various aircraft limitations are not exceeded. These are known as “Hard” limits (Spitzer, Ferrell 2015: 224). These flight envelope protections are removed in Direct Law, however this law can’t be manually selected by the crew (Ibsen 2009: 343).

On the other hand, Boeing has stated in its design philosophy that “The pilot is the final authority for the operation of the aeroplane” (Spitzer, Ferrell 2015: 224). This is incorporated into the design of its fly-by-wire aircraft by allowing the pilot complete control authority of the aircraft, regardless of whether this results in departure from the normal flight envelope (Harris 2011: 379).

Why is there a difference in philosophy?

Airbus introduced this ‘hard limit’ philosophy and subsequent technology into its Airbus 320 aircraft which entered service in 1987. Given that the majority of airline accidents are caused by Human Error (Wiegmann, Shappell 2016: 10), it could be considered that such technology was introduced on an ideological basis on the premise that it enhanced flight safety. This technology has been consistently applied on all Airbus models since the A320, simplifying and streamlining crew training and aircraft maintenance resulting in cost reductions for the airlines (Ibsen 2009: 347).

Boeing made a conscious decision to embrace the philosophy of full pilot authority over the aircraft through being able to override any fly-by-wire system, when the B777 was introduced, which was the first Boeing aircraft to incorporate such technology (Ibsen 2009: 347). With an extensive history of aircraft design, this allowed a degree of commonality and continuity for Boeing aircraft pilots (Ibsen 2009: 347). The flight crew have the ability to simply fly the aircraft unrestricted whether they are operating old, new, small or large airframes from the Boeing family.

Conclusion

There are clear aesthetic similarities between the two flight deck designs which are likely as a result of the certification requirements stipulated in CS/FAR-25. However, there are clear differences in automation philosophy, with Airbus restricting pilot control authority, ensuring the aircraft remains within a predetermined flight envelope (Harris 2011: 379). On the other hand, Boeing allows the pilots operating its aircraft have complete control authority if necessary (Harris 2011: 379).

References

Airbus. (2017) ‘The Airbus Cockpit Philosophy’ Proceedings of Flight Operations Safety and Awareness Seminar, ‘Airbus Flight Operations Support and Training Standards’. Held 19-21 September 2017 in Nairobi.

European Union Aviation Safety Agency (EASA), Certification Specifications and Acceptable Means of Compliance for Large Aeroplanes CS-25, Amendment 24. available from < https://www.easa.europa.eu/sites/default/files/dfu/CS-25%20Amendment%2024.pdf> [10 January 2020]

Harris, D. (2001) Human Performance on the Flight Deck. London: CRC Press

Ibsen, A. (2009) ‘The politics of airplane production: The emergence of two technological frames in the competition between Boeing and Airbus’. Technology in Society 31, 342-349

Spitzer, C. Ferrell, U. Ferrell, T. Becker, SG. (2015) Digital Avionics Handbook. London: CRC Press, Taylor & Francis Group

Wiegmann D., Shapell S. (2016) A Human Error Approach to Aviation Accident Analysis. Oxford: Routledge