Introduction
Automatic take-off and landing systems have been in existent for many years and their usefulness have been well documented since the introduction of this technology. There are three main phases in a typical automatic flight system. They are take-off, navigation and landing with each of them using different control laws and methods (Stojcsics & Molnar, 2013). Automated systems are used to relieve the workload of pilots, especially during critical phases of flights such as take-off and landing. Approximately 50% of all UAS accidents are attributed to human factors, with a significant portion occurring in the landing phase because of the difficulty to control the UAS under adverse weather conditions with limited situational awareness (You et al, 2012).
Automation in manned and unmanned aircraft take-off and landing
The total reliance on automation in both manned and unmanned aircraft has been widely debated. A classic example where an automated system might not be able to perform better than humans is the case of the Hudson River landing of US Airways Flight 1549 in 2009 where the pilot thought out of the box and chose to land on water, saving everyone on board the aircraft. However, if this was the case of an unmanned aircraft, having a remote human intervention might not be the best way to offset the rigidity of automation (Atkins, 2012). Automatic take-off and landing technology in both manned and unmanned aircraft systems are quite similar in a way that both systems largely make use of global positioning system (GPS) and the instrument landing system (ILS) for landing. In manned aircraft, automation has reduced cockpit flight crew from five to just pilot and co-pilot today, whose jobs are also significantly simplified.
Boeing 737
According to Richards (2012), most manned commercial aircraft pilots still prefer to manually perform take-off and landing, despite knowing that the automatic system available onboard is fully capable of such tasks. The Boeing 737 has two-autopilot, fail-passive system capable of category IIIA operations (Cohen et al., 1995). As like most other aircraft systems, the autopilot has redundancies incorporated to mitigate the risks of any system failure. Boeing 737 is able to have automatic flight by making use of its auto-throttle system that automatically varies the engine power from start-up to take-off through climb, cruise, descent and landing using avionics such as its flight control computer and flight management computer. However, the automatic flight can also be disengaged when certain events take place, such as loss of electrical or hydraulic power, inertia reference system failure, or the manual override activation by pilot using the autopilot disengage switch (Smartcockpit.com, n.d.). In this way, there is always an avenue for the flight crew to manually control the aircraft when necessary.
Global Hawk
The Global Hawk is a fully autonomous UAS which has the capability to automatically take-off and land without human intervention. The aircraft will follow a computer controlled flight plan throughout its flight unless there is a need for manual override due to system malfunction or any other emergencies. Since it is a high altitude and long endurance (HALE) UAS, it makes sense to automate the take-offs and landings due to the known data-link control latency present in any long range operations. The aircraft performs its autonomous take-offs and landings using its ground based launch and recovery element (LRE). The precise altitude and speed information is provided by high precision GPS for flight control. Within the aircraft, it has an inertia navigation unit which augments the GPS for automatic point to point navigation (Lee, 2009). The Global Hawk ‘pings’ the ground stations to maintain communications. If it determines that communication is lost, it will go into some form of self-diagnostic mode, using a back-up radio, checking circuit breakers, and finally flying itself through a serious of known waypoints to land itself with GPS and radar if all else fails (Ross, 2011).
According to You et al. (2012), most of today’s UAS incorporate level 2 automation where attitude stabilization and guided navigation technology are good enough. However, the Defense Advanced Research Projects Agency (DARPA) has recommended to have all future UASs use level 3 automation where the conventional workload on pilots such as take-off, landing, reconnaissance, ground attack missions can be reduced to allow pilots to concentrate on higher priority tasks (as cited in You et al., 2012, p. 1).
Recommendation and Conclusion
Having automation capabilities for all flight phases of both manned and unmanned aircraft systems has many advantages. The level of automation required for each of these systems will depend on their roles and mission requirements. In manned aircraft, appropriate automation has been proven to reduce the workload of pilots, but at the same time, it can also lead to complacency and skill erosion (Drappier, 2012). For unmanned aircraft, automation has been reported to have led to boredom and degraded vigilance while reducing workload (Cummings, Gao, & Thornburg, 2016).
In conclusion, there is always a need for a human to have oversight over the incorporated autonomous system regardless of automation levels and to intervene when required. This is because it is practically impossible for any designer to anticipate all scenarios encountered by the aircraft such as unexpected traffic, onboard system failures, or any erroneous and conflicted data, and cater accurate counteractions during the aircraft design phase. There will still be conditions that will render such automatic systems inappropriate.
References
Akins, E.M. (2012). Certifiable autonomous flight management for unmanned aircraft systems. The Bridge on Frontiers of Engineering, 40(4), 35-43. Retrieved from https://www.nae.edu/Publications/Bridge/37526/37584.aspx
Cohen, C. E., Cobb, H. S., Lawrence, D. G., Pervan, B. S., Powell, J. D., Parkinson, B. W.. . SWIDER, R. J. (1995). Autolanding a 737 using GPS integrity beacons. Navigation, 42(3), 466-486. doi:10.1002/j.2161-4296.1995.tb01901.x
Cummings, M. L., Gao, F., & Thornburg, K. M. (2016). Boredom in the workplace: A new look at an old problem. Human Factors, 58(2), 279. doi:10.1177/0018720815609503
Drappier, J. (2012). The erosion of manual flying skills. Retrieved from http://halldale.com/files/halldale/attachments/Drappier_0.pdf
Lee, T.W. (2009). Military technologies of the world. Westport : Praeger Security International.
Ross, P.E. (2011, November 29). When will we have unmanned commercial airliners? Retrieved from http://spectrum.ieee.org/aerospace/aviation/when-will-we-have-unmanned-commercial-airliners
Richard, J. (2012, November 2). How often are commercial flights landed using autopilot? Retrieved from https://www.quora.com/How-often-are-commercial-flights-landed-using-autopilot
Stojcsics, D., & Molnár, A. (2014). Autonomous Takeoff and Landing Control for Small Size Unmanned Aerial Vehicles. Computing and Informatics, 32(6). Retrieved from http://www.cai.sk/ojs/index.php/cai/article/view/992/609
Smartcockpit.com (n.d.). Boeing 737 systems review: Automatic flight. Retrieved from http://www.smartcockpit.com/docs/B737-Automatic_Flight_Systems_Summary.pdf
You, D. I., Jung, Y. D., Cho, S. W., Shin, H. M., Lee, S. H., & Shim, D. H.A guidance and control law design for precision automatic take-off and landing of fixed-wing UAVs. AIAA Guidance, Navigation and Control Conference. () doi:10.2514/6.2012-4674
No comments:
Post a Comment