Automatic take-off and landing of a
Boeing 737 and a Predator B
The two aircraft chosen for review
are the Boeing 737 (manned) and the Predator B (unmanned). Automatic take-off and landing systems have
come as an increasingly beneficial feature in many manned an unmanned
aircraft. These systems were essentially
designed to allow for safe landing in areas or situations previously thought
too difficult to land in; this include areas of poor visibility or in adverse
weather conditions (Larson, 2012).
Therefore, although it may often be ideal to have manned take-off and landing,
it sometimes may be impossible or unfavorable to do so.
The Boeing 737 utilizes an automatic
landing system termed “autoland”.
Autoland systems typically consist of several components including an
instrument landing system (ILS) radio that is responsible for receiving
localizer and glideslope signals to help interpret the direction from the ILS
frequency transmitter on ground for the approaching aircraft (Craig, Houck,
& Shomber, 2003). The automatic
landing system of a Boeing 737 involves approximately 6 major phases upon
descent. The first two consist of the
automatic approach. In this case, the
ILS radio utilizes the localizer and compass to determine azimuth and measures
barometric height to determine elevation (Craig et al., 2003). The next four phases are the automatic land
phases including leader cable, attitude, flare, and kicking off drift (Craig et al., 2003).
Briefly, the pilot will first establish
an approach. Once this is done, the
pilot will follow the ILS approach path that is indicated to him/her by the
localizer. The pilot then descends down
the glide path to the decision height where he/she must determine weather or
not there is enough visual information for a safe landing. Safety precautions have been made in the
design so that once autoland is engaged and have received ILS signals it will
automatically land without any further human intervention and can only be
disengaged by disconnecting the autopilot completely (Craig et al., 2003). There are also redundancies in the system
(typically at least two or three independent autopilot systems working
together) to protect against any system failures and improve safety (Craig et
al., 2003). The Predator B’s autolanding
system functions differently.
The Predator B is an unmanned aircraft
used for intelligence, surveillance, and reconnaissance (General Autonomics,
2013). The Predator B can successfully
complete automatic takeoff and landing capability (ATLC) landings through its
use of autonomy. This UAS can autonomously
track the centerline, reduce speed as necessary and even initiate the brakes
once it has reached its targeted ground speed (Kasitz, 2012). Additionally, the Predator B unlike the
Boeing 737 is also able to takeoff autonomously, utilizing similar procedures
to the landing. The Predator B’s
automated takeoff and landing also have the option of being fully autonomous or
assisted. In the latter, the pilot may
perform certain actions, essentially acting as a supporting pilot as the
Predator’s system takes over the remaining tasks. Conversely, a pilot may also regain full
control of the UAS and completely control the take-off and landing of the
Predator, which is often the case (Austin, 2010). The availability of these various flight
options of the Predator adds a layer of safety to the system.
Safety is always a primary concern in any
flight operation, as such both the autoland of the Boeing 737 as well as the
ATLC and controlled landing of the Predator B help improve safety. In the case of the Boeing 737, as once the
autoland is engaged it is essentially locked in place for landing in order to
avoid potential accidents (i.e. accidentally changing landing details). Redundancies are also in place to improve
safety. The Predator on the other hand
has several control options from fully autonomous, to partially autonomous and
even fully controlled to help improve safety.
Although all these options have their
benefits and drawbacks, this author recommends a partial automation level as
the best system to install in future variants of the Boeing 737 and Predator
B. The Predator B already contains this
level of automation, however having a shared level of autonomy and pilot
control seems to be the safest option as it offers an additional layer of
decision-making. This serves as a kind
of ‘safety net’ with the pilot and the automated system performing as a sort of
‘check and balance’ for the other.
Perhaps instead of having 3 redundant systems in the UAS as previously
mentioned, the Predator could have 2 redundant systems and a third system
replaced with human control as the ‘check’ on the system. However, future research would need to be
studied in order to determine the plausibility of this design.
References
Austin,
R. (2010). Unmanned Aircraft Systems. West Sussex, United Kingdom: John Wiley
&
Sons Ltd.
Craig,
R., Houck, D., & Shomber, R. (2003, April 1). Approach navigation options.
Aeromagazine, 12-21.
General
Autonomics. (2013). Predator B UAS. Retrieved from http://www.ga-
asi.com/products/aircraft/predator_b.php
Kasitz,
K. (2012, September 17). Predator B Demonstrates Automatic Takeoff and Landing
Capability. Retrieved from General
Autonomics: http://www.ga-asi.com/news_events/index.php?read=1&id=400
Larson, G. (2012, August 1). The
first autolanding. Air & Space Magazine.
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