Abstract
This paper analyzes the effect of space weather storms on the current navigation, communication and traffic surveillance systems. According to Afraimovich, E. L., Demyanov, V. V., Gavrilyuk, N. S., Ishin, A. B., Smolkov, G. a. (2009) powerful radio emission from the sunduring solar flares on December 6 and 13, 2006, and October 28, 2003 caused a malfunction of satellite navigation systems GPS and GLONASS. The SUMI telescope designed by NASA engineers and physicists takes complex measurements near the sun’s corona. It also shows that the resulting X-rays, ultraviolet radiation and CME can interfere with long-range radio communications, and strong flares can disrupt GPSBeasley, S. (2008). This paper will also examine different other problems affecting COM, NAV and surveillance systems;and will suggest some recommendations based on the outcome of the analysis.
Introduction
Advances in modern technology have brought new innovations into the aviation industry which not only have made flights faster and smoother for passengers but have in effect enabled a more precise and accurate means of navigation and communication. Navigations systems such as GPS (Global Positioning System), INS (Inertial Navigation System) and RNAV (Radio Navigation/ Area Navigation) have in effect revolutionized the ability of pilots to accurately and succinctly point out their general location in relation to their destination. There systems combined with high frequency radio communication and current methods of radar surveillance have created an effective and safer method of mass transit aviation enabling literally millions of travelers to safely traverse the open skies with ease and comfort. It must be noted though that like all technological instruments such systems are vulnerable to eventual malfunctions. While there are literally a plethora of different ways in which navigation and communication systems could potentially break down this paper will explore the possibility of the interaction between navigation and communication systems with various forms of space weather phenomena. As such this paper will examine how Space weather affects Com (Communications), Nav (Navigation) and ATM and what would be a suitable solution to resolving this dilemma?
One of the current mistaken assumptions by the general public is that inter-solar activities (activities which occur within the solar system) only occur within the areas between planets and have no effect on the localized environments within atmospheres such as those on Earth. Fisher (2003) refutes this fallacious example by the general public by explaining that not only does space weather phenomena affect localized environments within Earth’s atmosphere but it has a direct impact on the aviation industry itself. It must be noted that space weather phenomena is the result of bursts of protons and electrons from solar activity which create distinct inter-solar phenomena that can varied effects ranging from solar wind, coronal bursts of energy and other similar displays of energy. Fisher (2003) explains that not only do these bursts of energy cause changes in weather patterns but they also have the tendency to cause various forms of electrical equipment to malfunction (Fisher, 2003).
In their work examining the effects of space weather phenomena and communication systems Afraimovich, Demyanov, Gavrilyuk, Ishin and Smolkov (2009) explain that solar flares in particular have been known to disrupt High Frequency (HF) radio communications and various types of satellite signals creating periods of information blackouts for pilots (Afraimovich, 2009). What must be understood is that if such periods occur infrequently and for only a short time then they represent only a small hindrance to a pilot’s ability to safely fly and navigate a plane. It is only in extended periods of information blackouts where a pilot is cut of from both satellite navigation systems and high frequency radio communication with their intended destination that causes a great deal of concern (Fisher, 2003).
Another apparent assumption made by the general public regarding airplanes is that pilots in effect “fly” the plane throughout the entire experience. In reality, for most of the trip, planes fly utilizing an onboard autopilot that flies on a preset course destination that is set by the pilots and is guided by an onboard GPs navigation system. In conjunction with the RNAV and INS systems a planes onboard computer is able to determine its distance away from its target destination and as a result creates an efficient flight path from its point of origin to its intended destination (Barcheus, 2008). What must be understood though is that this system is inherently dependent on the onboard GPS navigation system in order to properly determine a planes current position in relation to its intended destination (Barcheus, 2008). Going from one destination to another is not as simple as pointing the plane towards that particular direction and going forward in a straight line rather due to the inherent curvature of the Earth’s surface as well as its continuous rotations as well as various weather phenomena a plane can attempt to reach a destination by following a straight line however it is highly unlikely this is achievable over long continent to continent air trips (Thomas & Rantanen, 2006).
Another factor to consider is that all planes follow a set of preplanned “routes” that have been set with both local and international aviation authorities, the reason for this is quite simple if there are no pre planned routes and estimated times of arrival then the possibility of mid-air “congestion” occurs on particular flight paths resulting in the possibility of increased rates of collision. The potential for these particular incidents are explored by Barcheus (2008) when he examines the construction of the new ATM system in order to replace the older ATC system.
Based on the given data it can be seen that uninterrupted GPS navigation as well as HF communication serves a vital role in ensuring safe travel through the skies (Fisher, 2003). It enables planes to know their position in relation to their preplanned flight path and as such reduces the risk of going off course or worse yet setting the plane on a collision course with another aircraft. With various space weather phenomena posing a potential risk for these vital systems through disturbances which affect communication and electrical equipment this poses a substantial risk for the airline industry since it would increase the likelihood of planes going off course and potentially disrupting the flight paths of other airplanes.
This report will make several recommendations, the most urgent being the need to create effective processes and strategies to prevent space weather phenomena from unduly affecting navigation and electrical equipment as well as the need to establish proper preventive measures in relation to observing when space weather phenomena occur and take appropriate measures of prevention. It is expected that the outcome of this study will show the direct connection between space weather phenomena and their effects on navigation and communication systems and such through the analysis of their effects proper preventive measures can be determined and utilized by the aviation industry. This report will answer its thesis question for the following primary audience, the National Transportation Safety Board (NTSB), using a technicality level that is medium in terms of academic breadth and depth.
Discussion
Based on its integration into the current aviation industry it can be seen that GPS navigation serves as an integral aspect of aerospace aviation however as Fisher (2003) explains such systems remain vulnerable to occurrences of space weather phenomenon which affects their ability to provide accurate data (Fisher, 2003). GPS systems utilize groups of satellites in geo-synchronous orbit in order to determine the precise location of a person, plane or object via a GPS receiver receiving coordinate transmissions from four or more GPS satellites (Nordwall, 1997). What must be understood is that this particular system utilizes a method of satellite triangulation where several satellites in varying positions enable a precise measurement of where a GPS receiver is relative to a pre-programmed “map” of the general area (Nordwall, 1997). It is through this method of triangulation that planes gain the ability to precisely determine their exact position relative to their intended destination. Fisher (2003) explains that “during a geomagnetic storm, the altitude of the lower boundary of the ionosphere changes rapidly and can introduce errors of several meters, since GPS operates by transmitting radio waves from satellites to the ground, aircraft, or other satellites, it is therefore sensitive to ionospheric changes due to geomagnetic storms” (Fisher, 2003).
While a few meters may not seem like much since most aircraft are hundreds of meters in the air the fact remains that even a difference of a few meters is sufficient to create cumulative errors in navigation systems resulting in the distinct possibility of planes either approaching too low or too high towards their prospective run ways. In fact based on various cases of “near miss” crashes where pilots approached too fast and too low the apparent cause was equipment error giving false readouts based on the GPS (Beasley, 2008).
What must also understood is that due to the inherent nature of geomagnetic storms they have the tendency to cause high frequency signal blackouts which affects integral navigation systems such as the aircraft’s Radio Navigation/Area Navigation system (Beasley, 2008). The RNAV or Radio Navigation/Area Navigation system utilizes a network of navigation beacons established in various areas enabling aircraft to choose any prescribed course to and from particular destinations utilizing the beacons as navigational guides. What this particular system does is that it enables pilots to choose more efficient routes to get to particular destinations thus allowing them to conserve the overall flight distance covered, enables pilots to have more options in terms of travel routes when unexpected storms occur, and reduces the possibility of congestion in various highly travelled areas thus alleviating the risk of mid-air collisions (Thomas & Rantanen, 2006).
Since RNAV systems utilize high frequency transmissions as a method of data transmission between navigational beacons and planes these are usually the first systems to incur radio frequency blackouts which prevent pilots from determining their position relative to the next signal beacon (Thomas & Rantanen, 2006). What must be understood is that high frequency methods of communication are utilized by the aviation industry due to their wavelength ranges which can range from 1 to ten decameters which are ideal for communicating between long distances. It is due to this that it is the current preferred method of communication between ATCs and aircraft making it one of the primary standards of communication in the aviation industry.
On March 24, 1940 a “great” geomagnetic storm rendered inoperative 80% of all long-distance telephone connections out of Minneapolis, Minnesota. Electric service was temporarily disrupted in portions of New England, New York, Pennsylvania, and Minnesota, as well as Quebec and Ontario, Canada (Fisher, 2003). As mentioned earlier the problem lies not in the fact that frequency blackouts occur but rather that they occur over a prolonged period of time.
Various studies examining the effects of space weather, particularly geomagnetic storms, have shown that on average solar weather disrupts not only high frequency communication signals but also has the potential to damage electrical equipment as well (Burch, 2004). For example, from the 13th to the 14th of March 1989 a severe geomagnetic storm caused a system wide power failure in Quebec, Canada, resulting in the loss of over 20,000 megawatts (Fisher, 2003). The blackout cut electric power to several million people, time from onset of problems to system collapse was about 90 seconds and high frequencies were virtually unusable worldwide, while very-high-frequency transmissions traveled unusually long distances and created interference problems (Fisher, 2003). It was even noted that a Japanese communications satellite lost half of its dual-redundant command circuitry as well as a NASA satellite dropping 3 miles (4.8 km) in its orbit due to the increase in atmospheric drag (Fisher, 2003). Additionally, Fisher (2003) notes that “the frequency navigation signals used by maritime and general aviation systems (Loran-C) may experience outages on the sunlit side of the Earth for many hours during periods of geomagnetic storms or solar wind causing loss in positioning” (Fisher, 2003). The reason behind this is the resulting free electrons generated by solar weather which can and often do damage systems that are inherently dependent on electricity. These free electrons build up in the electrical systems subsequently causing an electrical discharge which overloads the electronics and causes them to shut down or even subsequently destroy themselves (Burch, 2004). While planes are sufficiently protected from such occurrences through multiple redundancy systems and insulated instruments the fact remains that RNAV systems located on the ground as well as GPS satellites located in space can be affected and most often are by such storms (Anselmo, 1998). This results in not only the potential for a complete blackout for external sources of navigational data but presents a potentially hazardous situation for pilots since it affects their ability to properly determine where the plane is in relation to their destination (Thomas and Rantanen, 2006)..
What must also be taken into consideration is the fact that alternative methods of navigation such as the INS or inertial navigational systems cannot be utilized as an effective navigational system over time. INS systems utilize onboard motion and rotation sensors in order to calculate the relative distance and position travelled by the plane based on the sensor read outs started at the time of take off (National Airspace System, 2000). It uses a series of accelerometers, motion sensors and gyroscopes in order to create an accurate read out of the plane’s position relative to a grid created by the computer. What must be understood is that an INS system actually does not require external references once it has been initialized, namely information from satellites and navigational beacons, in order to determine its position, velocity and orientation (National Airspace System, 2000).
Unfortunately, as mentioned earlier, this particular system cannot be utilized as a primary method of navigation since it suffers from a problem known as integration drift wherein small errors involving acceleration and angular velocity measurements become compounded over time which results in distinct errors in positioning (National Airspace System, 2000). The reason behind this is actually quite simple, the new position of the plane utilizing the inertial navigation system is calculated based on the plane’s previously calculated position and its inherent acceleration and velocity at the time. Unfortunately external environmental factors such as wind resistance, gravity and some other phenomena actually results in tiny errors occurring in the calculation (National Airspace System, 2000). These errors become cumulative overtime resulting in inaccurate readings which could potentially cause problems for both the pilots and various onboard navigational systems. This is resolved through the input of external data periodically into the system however with no external data sources coming from RNAV or GPS systems when a geomagnetic storm occurs this in effect makes the pilots reliant on an increasingly inaccurate system of determining their exact position (National Airspace System, 2000).
What must be understood when examining today’s system of communication is that it is inherently reliant on the use of particular radio frequencies in order to facilitate communication (Burch, 2004). These frequencies utilize alternating currents to carry radio signals both to their point of destination and back again. It must be noted though that the basis of all radio technology is the use of electromagnetic waves in order to carry signals back and forth which utilizes the air itself as a conductor for the signal (Burch, 2004). Unfortunately, due to the inherently electrical nature of these signals and the fact that they utilize air as a medium of communication this leaves the process vulnerable to interruptions from large sources of free electrons which disrupts the entire process.
Nordwall (1997) explains that various forms of space weather phenomena ranging from geomagnetic storms, solar radiation storms, and solar wind all interact with the atmosphere differently however they are a source of free electrons which causes a sufficient enough interaction with the atmosphere that they can in effect cause complete radio black outs on HF frequencies (Nordwall, 1997). In fact it has already been noted that a sufficiently powerful geomagnetic storm can cause a complete HF frequency blackout on the entire sunlit side of the Earth for a number of hours which affects the ability of pilots to contact air traffic controllers at their intended destination (Afraimovich, 2009). While various ATC stations do have alternative means of communication this is not applicable to all cases especially in areas such as the Polar region, Russia and several areas in Asia which are all high traffic regions for aircraft.
ATC or Air Traffic Control, is a system that is ubiquitous with literally every airport in the world wherein a ground based system of controllers helps to direct and organize the flow of air traffic by providing information to pilots in order to prevent collisions, organize the movement of planes and to generally ensure efficient usage of air space above airports (National Airspace System, 2000). On average ATC towers have almost a dozen systems for managing air traffic ranging from flight data processing systems, short term conflict alert systems, minimum safe altitude warning systems to even departure and arrival coordination systems (National Airspace System, 2000). It must be noted though that all these systems are inherently dependent on two particular technologies need to track planes in the sky, namely: radar and the ATCRBS or air traffic control radar beacon system (National Airspace System, 2000).
As mentioned earlier space weather phenomena interferes with the transmission of signals that utilize electromagnetic waves, as such, radar (which is the primary method of aircraft detection) would of course be affected since it is based on this particular technology. Radar systems work by using electromagnetic waves as a means of determining the direction, altitude, speed and range of particular objects. This is done by emitting an electromagnetic wave is particular direction or in an omni-directional position and determining the direction, speed, range etc. based on the rate in which the signal bounces back (National Airspace System, 2000). Such a system has been used extensively in the aviation industry for well over 40 years or more and as such has become and integral facet of ensuring proper aviation safety (National Airspace System, 2000). The free electrons produced by various space weather phenomena cause either delays or outright interference in electromagnetic wave transmissions resulting in the radar image coming back as a garbled stream as compared to its usually method of return (Afraimovich et al., 2009). Not only does this affect the ability of air traffic controllers from properly determining the current location of aircraft the subsequent delays brought about by storms results in the possibility of incorrect instructions being given which increases the likelihood of mid-air collisions (Barcheus, 2008).
One possible alternative to facilitate proper air traffic control is the ATCRBS or air traffic control radar beacon system, this system is a form of “enhanced” air traffic control wherein transponders installed within aircraft broadcast a signal which is received by secondary surveillance radar systems located within ATC towers (National Airspace System, 2000). The primary and secondary radar systems work in conjunction in order to produce an accurate image of all aircraft traffic within a given airspace being monitored by a particular ATC facility thus enabling a far more accurate and precise method of controlling aircraft traffic within the area (National Airspace System, 2000). Unfortunately, the use of the ATCRBS as an alternative means of detection is also unlikely since it utilizes the same technological concept as radar technology and thus cannot be utilized effectively during solar weather occurrences. Based on this it can be seen that an alternative system needs to be devised in order to prevent potential aerial disasters that may occur as a result of solar weather interference.
There are two particular NextGen flight systems which show potential as a replacement for current ATC systems namely the AACS (Automated Airspace Computer System) and the TSAFFE (Tactical Separation Assisted Flight Environment. The AACS concept supposedly will utilize a ground based system that directly interacts with cockpit systems by providing information in relation to trajectories and traffic clearances via a data link that would give pilots the information they need at a far faster rate as compared to the current system utilized (Barcheus, 2008). On the other hand the TSAFFE system will act as a “safety net” in which it will monitor aircraft independently from the ACCS system in order to ensure conformity to the direction given by the ACCS and issue warnings to pilots when necessary (Barcheus, 2008). Both of these systems will be part of the Automated Airspace concept which aims to reduce the amount of errors in direct relation to the current ATC system.
Conclusion
Based on the various facts and arguments presented in this paper it can be seen that current navigation, communication and ATC systems are inherently vulnerable to the occurrence of solar weather. Prolonged communication, navigation and radar blackouts not only could cause potential disasters in terms of increasing the possibility of mid-air collisions but it also increases the likelihood of cockpit error resulting in a significant amounts of danger for passengers. It is based on this that it can be seen that there is a distinct necessity to develop alternative means of navigation, communication and ATC in order to mitigate this dilemma. On the other hand it must also be noted that substantial solar weather phenomena does not occur on a regular basis. Based on the observations of Fisher (2003), there have been only 15 or so occurrences of solar weather phenomena that have actually caused significant communication and electronic errors within the past 60 years. It must be noted though that various scientists have stated that the sun is currently entering an active phase in its solar cycle and as such this increases the likelihood of the development of various cases of solar weather phenomena. Since technological innovations take time for proper implementation new processes and procedures would need to be created in their place till such a time that technology has advanced to such a degree that solar weather phenomena does not present itself as a significant danger to aviation safety.
Recommendations
The following are a set of recommendations that have been devised as appropriate procedures and processes that can be effectively implemented in order to prevent possible problems in relation to solar weather phenomena.
- Establishing daily scientific examinations of the sun in order to predict the occurrence of solar weather phenomena through which proper warnings can be given.
- Establishing a general rule in aviation specifically stating that in cases of predicted solar weather phenomena planes should be grounded until the storm has passed
- Utilizing alternative means of guidance such line of site laser guide markers located in various areas in order to help pilots determine their current location based on the type of laser signal utilized.
- Implementing aviation policies that allow pilots to carry more fuel in cases where it has been determined that solar weather may occur in order to for an aircraft’s crew to circle around a particular area in order to wait out the communication blackout
- Implementing the use of graphical charts in order for pilots to approximate their current distance from their destination based on their estimate of their last known position relative to where they want to go.
- Establishing the use of graphical simulation systems which take into account previous flights and helps to determine the plane’s current position based on data from previous flights utilizing the same route and speed.
- Installing larger warning lights on planes and utilizing their increased capacity during periods of solar weather phenomena in order to increase visibility and lower the chances of collision.
- Implementing new procedures for planes to slow down their speeds in order to get to their destination slower than normal during periods of solar weather phenomena in order to give more time for the storm or pass and re-establish navigation and communication systems.
It is expected that should the following processes and procedures be followed the result will be an effective solution to resolving problems in relation to incidents related to solar weather phenomena.
References
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