Automatic Takeoff and Landing

        In the world of aviation there are manned and unmanned aircraft.  There is a certain level of automation that goes into each type of operation.  While most people assume unmanned aircraft fly mostly autonomously, it is not the case.  The opposite could be said for manned aircraft.  Both manned and unmanned aircraft utilize a certain level of automation as well as manual control.  There are advantages and drawbacks to each and in order to better understand them, further exploration into their systems is needed.  In regards to manned aircraft, the McDonnell Douglas MD-11 is a three-engine, medium to long range, wide body jet airliner that is capable of automatic takeoff and landing as well as being controlled manually by a pilot on board.  On the other hand, an unmanned aircraft with similar capabilities is Northrop Grumman’s RQ-4 Global Hawk; which is a High Altitude Long Endurance (HALE) fixed wing aircraft powered by a single turbofan engine.

        The McDonnell Douglas MD-11 was designed off of the need to upgrade the fleet of DC-10’s (Brown, 2012).  In the 1970’s and 80’s, the DC-10 was overwhelmed with catastrophic failures; including American Airlines Flight 191, which resulted in 270 deaths (Brown, 2012).  Instead of inventing a new aircraft, McDonnell Douglas used new technological advances in order to develop a next generation aircraft with minimal effort.  The advanced cockpit design included: Fly-by-wire technology, CRT displays, dual flight management system computer, hydraulic fuses to prevent loss of control in catastrophic conditions, central fault display system, GPS, and CAT III automatic landing capability for extremely bad weather (Brown, 2012).  The improved dual flight management system eliminated the need for a flight engineer, reducing the required crew to two (Brown, 2012).  The system also performs automated normal, abnormal and emergency checklist duties for major systems, further reducing the need for additional crew members (Boeing, n.d.).
        The CAT III automatic landing capability is the main focus of the MD-11.  When it comes to automatic landing technology, there are three categories (I, II, and II).  Category I only go off of altimeter indications for decision height, the Category II and III approaches go off the radar altimeter for a decision height.  Automatic landing uses the radar altimeter to determine the aircraft’s height AGL to initiate the landing flare at the correct height.  The localizer signal of the ILS may be used for lateral control even after touchdown until the pilot disengages the autopilot.  Once automatic land is engaged and ILS signals acquired, the aircraft will proceed to land without further intervention, and can only be disengaged by completely disconnecting the autopilot.  This prevents accidental disengagement of the automatic land system at a critical moment.  Three independent autopilot systems work in harmony to provide redundancy against failures.  A pilot can override the system, however pilots have reported that the controls of the MD-11 are highly sensitive compared to other aircraft and the airplane’s autopilot was not disconnecting when they input manual controls (Brown, 2012).  This has led to some resistance from pilots.
        As for Northrop Grumman’s RQ-4 Global Hawk, the unmanned element of the aircraft requires operators to control the aircraft from Ground Control Stations.  The Global Hawk utilizes two completely different ground segments, a Mission Control Element (MCE) and a Launch and Recovery Element (LRE) (airforce-technology, n.d.).  The MCE is used for mission planning, C2, and image processing; while the LRE is used for controlling launch and recovery (airforce-technology, n.d.).  The LRE provides precision differential GPS system corrections for navigational accuracy during takeoff and landings, while precision coded GPS supplemented with an inertial navigation system is used during mission execution (airforce-technology, n.d.).  The technology allows the aircraft to “sense” when it’s aligned with the runway and when to engage its brakes when landing (Ciccarone, 2014).  While the autopilot allows the aircraft to take off and land in adverse weather conditions, human factors still play an important role.  In December 1999, a Global Hawk was damaged when it overran the runway due to operators setting an excessive taxi speed (Peck, 2003).
        Even though auto landing and takeoff is a beneficial technology that reduces the workload of pilots and allows flying in adverse weather conditions, human factors still remain an important role.  Only when correct planning and usage of the technology is combined with sound execution of the auto pilot system is when successful operations occur.  Redundancy in the technology is key, but even more important is proper training and procedures for the pilots/operators.

References

airforce-technology. (n.d.). RQ-4A/B Global Hawk HALE Reconnaissance UAV, United States of America. Retrieved July 13, 2014, from airforce-technology.com: http://www.airforce-technology.com/projects/rq4-global-hawk-uav/
Boeing. (n.d.). Commercial Airplanes. Retrieved July 13, 2014, fromboeing.com: http://www.boeing.com/boeing/commercial/md-11family/
Brown, D. (2012, August 24). KLM Starts to Say Goodbye to the MD-11. Retrieved July 13, 2014, from airlinereporter.com: http://www.airlinereporter.com/2012/08/klm-prepares-to-say-good-bye-to-the-md11/
Ciccarone, P. (2014, June 12). RQ-4 Global Hawk makes first flight out of Misawa. Retrieved July 13, 2014, from misawa.af.mil:http://www.misawa.af.mil/news/story.asp?id=123414268
Peck, M. (2003, May). Global Hawk Crashes: Who’s to Blame? . Retrieved July 13, 2014, from nationaldefensemagazine.org: http://www.nationaldefensemagazine.org/archive/2003/May/Pages/Global_Hawk3871.aspx