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Volume 12, No. 1 |
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Pilot Program Awards $5,000 in Scholarships
Dayton Section Selects Two Recipients
The Dayton Section of the Institute of Navigation awarded two Dayton high school students with $2,500 in ION sponsored college scholarships. The goal of the section’s scholarship program is to address the serious lack of young technical professionals entering the field. The program was initiated with the hope that this modest commitment of the Institute’s resources will succeed in encouraging young people to become involved in technical navigation industries. The hope is that this year’s Dayton pilot program will give the ION enough experience to expand the scholarship program to deserving students sponsored by other ION sections.
While the pilot program is being funded by the ION Council, the award criteria and selection process was managed by a committee of Dayton Section members. Applicants were asked to submit a statement describing their interest in navigation technology, creative problem-solving, relevant extracurricular activities, and what they hope to gain from the scholarship, together with two letters of recommendation from high school faculty members or others qualified to comment on the applicant’s related accomplishments and work ethic. Applicants were also given the option of including other relevant materials.
Richard Thomas Lipscomb, Dayton Christian High School
Richard spent his senior year of high school enrolled in the Aviation and Pechnology program at Sinclair Community College where he completed a navigation systems class, and plans to continue in his study of aviation technology. Upon completing his Sinclair program, Richard hopes to continue his education in Ohio State’s Aviation Engineering Program.
Richard’s school advisors credited him with being a “self-motivated and industrious individual who carefully considers the opportunities that come before him.” His teachers noted that he has participated in numerous high school programs including two musicals, and three science fairs. He also has served as the school’s sound technician for school assemblies.
Richard spent this past year working evenings as a lineman at his local airport where his duties have included assisting the Fixed Base Operator, fueling planes and assisting customers with airman supply purchases. The objective of this part-time employment has been to gain practical experience from experienced airmen. This employment has helped fund his flight training.
Richard’s hobbies have included working with a local pilot to restore the engine of a World War II PV2 vintage bomber. He holds a private pilot certificate and hopes to become a professional pilot.
Casey Miller, Carroll High School
Casey is not a new face to the ION. Many will remember him, at age 16, as the ION’s youngest presenter of a paper at ION GPS 2000. The system he developed in 2000–2001 provided real-time capability to monitor and evaluate a runner’s performance during athletic training. By correlating a runner’s velocity (and position) with heart rate and the runner’s perception of work, post-workout or even real-time alternations could be made to accomplish enhancements. This truly remarkable, and very likely patentable, prototype won Casey a student sponsorship to attend the ION GPS 2002 meeting. It should also be noted that he won the highly competitive Best Presentation Award in his session both years! He is the youngest recipient of such a professional honor in the history of the Institute.
Peter Maybeck, professor of electrical engineering at the Air Force Institute of Technology, noted that “Casey has the innate capability to succeed at the highest level, as witnessed by his GPA. Moreover, he has a deep-seated dedication to excellence, a scholarly approach to investigative learning, and perseverance in accomplishing meaningful objectives. His creativity and self-initiative are second to none. He has demonstrated a capability to study a problem, to decipher the core aspects, to propose and evaluate alternative solutions, and to carry through a complex project to fruition.”
Casey is a noted athlete and is the varsity team captain of his high school’s cross country track team of which he has been a member for the past four years. He is also a member of the National Honor Society, a student council representative, and is active in his local community and church. Casey has enjoyed participating in numerous science events and competitions. He has been the recipient of numerous awards.
Casey wants to pursue an education in engineering and to develop “navigation related systems that will make people’s lives safer, easier and more effective.” Casey has noted his career ambition to be that of a “creative inventor.”
I think all would agree that he is well on his way!
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From the ION President: Ballots are Out, Much Has Been Done
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The ballot is out, and by the time you read this column, the votes will be tallied. My best wishes to all the excellent candidates nominated by this year’s Nominating Committee. I am very pleased with the quality of the professionals willing to provide their time and talents in the service of the Institute. The newly elected officers will take office on June 26, 2002, at the conclusion of the Annual Meeting.
I am also happy to report that the Dayton Section has awarded two Dayton high school students with $2,500 of ION-sponsored college scholarships. These awards are part of a pilot program the Council approved this past year. The goal of the Section’s Scholarship Program is to address the serious lack of young technical professionals entering the field. Our intention is that this modest commitment of the Institute’s resources will be successful in involving young people in our future programs. Our hope is that this year’s pilot program in Dayton will provide us with enough experience to expand this scholarship program in the future to deserving students sponsored by other ION sections.
National Office Relocation
Another item to note is that the ION National Office has relocated. As of June 1, it is located at 3975 University Drive, Suite 390, Fairfax, Va., 22030. You will receive an e-mail with new telephone and fax numbers. If you want to jot down the numbers, they are (703)-383-9688 and (703) 383-9689, fax. (All e-mail addresses remain the same. The relocation provides the National Office staff with needed additional space without increasing the ION’s total expenditures for building expenses.
Remember that the ION will have the ION “Red Book” Series available in a fully searchable CD-ROM in June. This CD will be sold at an introductory members-only price for a short period of time. Be sure to reserve your copy now! This is sure to become a valuable technical resource for your library.
Plan on attending the Satellite Division’s 15th International Technical Meeting, ION GPS 2002, September 24-27, 2002, in Portland, Oregon. General Chair, Dr. Gerard Lachapelle from the University of Calgary and Program Chair, Dr. A.J. Van Dierendonck from A.J. Systems have done an outstanding job of organizing a strong technical program. The ION GPS Plenary Session will focus on various types of interference in the GNSS frequency bands—intrasystem, intersystem, unintentional and intentional external interference. The planned panel discussion will draw upon perspectives and expertise of noted technical and policy leaders in GNSS to explore the present issues regarding GNSS signal compatibility and interoperability in presence of interference. You will not want to miss it!
Finally, since the conclusion of the Annual Meeting will mark the end of my term as president of the Institute, I want to thank all who have served in various capacities this past year. A special thanks is due to those of you who have served on the Council and also to the personnel at the National Office. It has been a pleasure working with you. You have made the experience an enjoyable one.
Regards,
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Executive Vice President: Dr. Rudy Kalafus Treasurer: Mr. Larry Hothem Eastern Region Vice President: Ms. Sally Frodge Central Region Vice President: Maj. John Raquet Western Region Vice President: Dr. A.J. Van Dierendonck Immediate Past President: Ms. Karen Van Dyke
Facsimile: 703-383-9689 Web site: http://www.ion.org E-mail: membership@ion.org
Technical Director: Carl Andren Assistant to the Technical Director: Miriam Lewis Meeting Services/Author Liaison: Connie Mayes Member Services/Registrar: Wendy Hickman Graphic Design/Editor: Paula Danko Information Manager: Rick Buongiovanni |
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Phil's Farewells
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It has been an exciting 15 months serving as the ION’s congressional fellow for Sen. James Inhofe (R-Okla.) as his science and technology advisor on defense policy.
My wife, Nancy, and I moved back to our home in Dallas, at the end of March where I have resumed my former professional life at my company, Navward GPS Consulting.
If you have been reading my articles, you know pretty much what my responsibilities were and the several special interest activities I pursued on the Hill. This final article will be devoted to the farewell parties … there were two.
The first was a wonderful surprise dinner planned by Sally Frodge (a good friend and ally from the Department of Transportation in the Ultra Wide Band (UWB) spectrum encroachment issue and a very active ION member) and Clark Cohen (the ION’s current congressional fellow). Clark invited Nancy and I to his apartment for dinner on March 14. His place is on the House side of the Capitol and less than a mile from the Russell Senate Office Building. I arranged for Nancy to meet me at the Capitol South Metro stop. As we walked toward Clark’s apartment, we were discussing what he might serve. We arrived about 15 minutes early and wondered whether Clark would be ready this early and finally decided that we could pitch in and help if he were in a bind with the cooking.
But lo and behold, not only was Clark there, but also Sally, Carl Andren (ION’s technical director), and Jim Doherty (the D.C. section chair) and his wife, Patti, who all greeted us with “Surprise!” Clark then informed us that we were going to be treated to dinner at a nearby fancy French restaurant after some wine, cheese and fruit at his apartment. Later we joined Dr. Scott Pace (another UWB ally who works at the White House executive office and formerly worked at the RAND Corporation), and Dr. James Farrell (a good tennis buddy and ION member from Baltimore), and his wife, Maria. The meal was delicious and the fellowship was delightful.
Afterward, Carl presented me with a beautiful United States Senate memorial coffee cup as a remembrance from the ION. Scott then presented me with a large photograph of the International Space Station with the Earth in the background. He called this a “just-in-time” memento (meaning that they all were going to sign it on the spot). Scott then penned: “With deepest thanks for your warrior spirit!” Carl: “Thanks to you and Nancy for starting off our Congressional Fellowship Program. You will be a hard act to follow. You’ve pioneered the way.” Clark: “It’s been great being here with you in D.C. (not to mention the Senate!). Thanks for all your ‘veteran advice’ in helping me get my feet wet. I greatly appreciate it.” Sally: “It was wonderful to have you both here. Thank you, Phil, for being the best First Fellow! (and thank you, Nancy, for being such a great First Lady of Fellow!).” Jim & Patti: “It has been an honor and a privilege to work closely with Phil for the past year—it went by too fast—and to get together socially. The wonderful thing is that we have made great friends—though you are leaving this area, our friendship remains.” Jim & Maria: “It is an honor to be a friend of you. You’re special. You are a true Christian gentleman and a great guy.”
I will always treasure the photo and the personal messages from persons whom I have loved and appreciated during my tenure on the Hill. I was touched beyond description by this demonstration of their friendship and appreciation.
Then Breakfast at the Senate
The farewell breakfast in the Sen. Inhofe’s office on the Tuesday morning before my departure was also a very memorable event. Sen. Inhofe himself scheduled it so that he would be able to attend. This was very special to me because he seldom attends farewell functions. He made a very warm speech and then gave me a big hug. My boss in the “War Room,” John Bonsell, then presented me with a large replica of an oil painting, “The United States Capitol in Summer 2001.” There were notes penned on the large white border from all of the Ssenator’s Washington, D.C. staff and many of the Armed Services Committee staff. At the bottom center is this note from the senator: “Phil—You are truly an American hero and it has been great having this part of your life with us. Thanks so much!” John’s note is to the right of the senator’s: “It has been a great year. I will miss you very much. You have been so supportive and helpful. Thanks for everything. Keep in touch. Good luck and God Bless.” Just to the left of the senator’s
note is this message from Glenn Powell, his chief of staff : “This has been a great year for us with you working here. We are going to miss you and we hope you will stay in touch.” To the left of Glen’s note is the following from Kim Cutter, the office manager: “It’s been wonderful getting to know you and your family. You have made such a difference while you’ve been here. Thank you for everything.” To the left of Kim’s message, Chad Bradley the legislative director, said: “Thanks for all your help. It’s been great having you in the office.” There were many other notes but I will conclude with the one from Donna Michalek, the AAAS congressional fellow taking my place: “Thanks for all your help getting me started here. I hope that I can measure up to the standard you have set. Good luck with your future endeavors.”
I am very grateful to the ION for sponsoring me as their first congressional fellow. I wanted to share these wonderful farewells with you because you made it all possible. These are treasured mementos of the most wonderful professional experience of my career!
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Kepler Award Nominations Requested |
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| Nominations are being accepted for the Johannes Kepler Award. The purpose of the award is to honor an individual for sustained and significant contributions to the development of satellite navigation. All members of the ION are eligible. | To submit a nomination, go to the Kepler Award Nomination Form, complete the form and submit. Or, send a supporting letter via fax (703-383-9689) or mail to: Satellite Division Awards Chair, The Institute of Navigation, 3975 University Drive, Suite 390, Fairfax, VA 22030, by Aug. 15, 2002. |
2001 FRP Is Released
By Michael E. Shaw and James V. Carroll
The secretaries of Transportation and Defense approved the 2001 Federal Radionavigation Plan, commonly known as the FRP in March 2002. More precisely, the secretaries actually approved the release of TWO radionavigation documents, the FRP and the Federal Radionavigation Systems (FRS). The material and content of the new FRP and FRS are similar to that in the previous, consolidated FRP. Splitting the old FRP into two interrelated and companion documents will allow for a more frequent and less time-consuming update of the more topical items in the new FRP, while leaving the more archival material in the FRS to be updated as needed, but probably less often.
The FRP/FRS is the definitive source for U.S. government policy and plans for radionavigation services provided by the U.S. Government. The FRP focuses on policies and plans for the U.S. government radionavigation systems. The FRS, on the other hand, presents the roles and responsibilities in managing the radionavigation systems, civil user requirements, and descriptions of the various systems.
The greatly expanded capabilities of today’s radionavigation systems, especially GPS, have led to their use in a variety of non-navigation applications. Those described in the FRS include geodesy, surveying, mapping, geographic information systems, geophysical and meteorological applications, and timing and frequency applications.
2001 FRP/FRS Highlights
The FRP/FRS reflect developments that affect the key federally-operated radionavigation systems. The systems include GPS and its augmentations, radiobeacons, ILS, VOR/DME, Loran-C, and TACAN. The FRP/FRS, published jointly by the Departments of Defense (DoD) and Transportation (DOT), defines and updates as necessary the official U.S. policies and operating plans for federal radionavigation services. Plans call for publication of the FRP no less often than biennially, and the FRS only as changes to a system architecture dictate, or as systems are added or decommissioned.
Recent FRPs, including the 2001 FRP/FRS, reflect the United States commitment to GPS and its various augmentations to improve both the safety and efficiency of the national transportation infrastructure. The United States will continue to provide GPS to civil users worldwide “free of direct charge.” GPS augmentations include the FAA Wide Area Augmentation System (WAAS) and Local Area Augmentation System (LAAS), the U.S. Coast Guard (USCG) maritime differential GPS (MDGPS) system, the Nationwide DGPS (NDGPS) system, and the National Geodetic Service (NGS) Continuously Operating Reference Stations (CORS).
Developments reported in the 2001 FRP include the following: turning off the DoD Selective Availability feature that deliberately degraded the accuracy of the GPS L1 civil signal, delay in the operation of the initial phase of WAAS, and consequent delay in the planned phase-down of many ground-based aeronautical navigation systems. In addition, modernization of GPS continues. A second civil frequency on the L2 band will be added to new GPS satellites beginning with launches in 2003, and a third civil signal that addresses aviation safety needs will be added on the L5 band beginning with launches in 2005.
WAAS Available For Non-Safety Uses
According to the 2001 FRP, WAAS is now available for non-safety uses for those equipped with GPS-WAAS receivers, which are becoming increasingly available. Following resolution of various technical issues, the commissioning of WAAS for safety applications is now expected to occur in 2003. In addition, the LAAS Category I capability is expected to be achieved in 2003, and the Category II/III capability is expected in 2006. NDGPS, providing dual-coverage service throughout continental United States, is expected to be fully operational by the end of 2007.
Phase-Down Anticipated
The 2001 FRP anticipates a phase-down of the ground-based aeronautical aids (VOR/DME, ILS, and the military version of VOR/DME, TACAN) to begin in 2010. This date, a two-year slip from that reported in the 1999 FRP, is tied to WAAS performance. Under the plan, the phase-down will leave a minimum operational network of several hundred VOR/DME facilities, some Category I ILS, and all Category II/III ILS facilities, to serve primarily the busiest airports for all flight phases, in the case of satellite disruption. There has been no additional MLS system development, and phase-down of this system will begin in 2010.
In addition to the FAA ground-based aids, backup systems could include inertial navigation systems, a barometric altimeter/GPS combination (which may be able to meet navigation requirements through nonprecision approach for GPS unaugmented by WAAS or LAAS), Loran-C, or a combination of systems. Regarding the status and future use of Loran-C, the 2001 FRP maintains the policy of continuing to operate Loran-C in the short term while continuing to evaluate the long-term need for its continuation. The government will give users reasonable notice if it concludes that Loran-C is not needed or is not cost-effective.
In summary, federal radionavigation planning is a dynamic process in which DOT is seeking a sensible transition to satellite-based navigation services as key element of our national transportation infrastructure while recognizing the need to maintain backup navigation aids where required.
2001 FRP Availability
The 2001 FRP is now available on the Internet through the USCG Navigation Information Service, 703-313-5900, or http://www.navcen.uscg.mil, and the Interagency GPS Executive Board Web site, http://www.igeb.gov. The FRP/FRS also can be obtained on a CD-ROM from the DOT Volpe National Transportation Systems Center (fax request to J. Carroll, Volpe Center for Navigation, 617-494-2628.), and printed documents are available at a nominal cost from NTIS.
—Michael Shaw is the director of Radionavigation and Positioning, Office of the Assistant Secretary for Transportation Policy, Washington, D.C.
-James Carroll is with the Department of Transportation’s Volpe National Transportation Systems Center, Cambridge, Mass.
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Musings on the Sun
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Blast From the Past
The following article originally appeared in the ION Journal, NAVIGATION in June 1952 (Vol. 3, No 4).
It appears that some navigators do not understand why the sun appears larger at sunset and sunrise than it does at noon. One of the more popular misconceptions is that it is caused by refraction. Actually, refraction makes the sun appear smaller at rising or setting, because there is more refraction acting on the lower limb of the sun (because of its lower altitude) than on the upper limb. You can check this. Measure the horizontal and vertical diameter of the sun at noon with a transit. You will find it approximately 32 minutes of arc each way. Repeat this measure- ment at sunset. The horizontal diameter will still be 32 minutes of arc. The vertical diameter will be approximately 27 minutes.
Our eyes give our brains a false impression of apparent size for the following reason: To the observer on the surface of the earth, the sky looks like a large, flat dome instead of a hemisphere. Points on this flat dome which are at the observer’s zenith appear to be nearer to him than points on the rim of the dome (the observer’s horizon). Haze near the horizon aids the illusion of greater distance. The human eye automatically makes allowance for distant objects appearing smaller than closer objects of the same size. The image of the sun received by the eye is the same size (discounting the refraction effect) at both the horizon and the zenith. However, because of the illusion of greater distance at the horizon, the eye makes an adjustment in the message transmitted to the brain and the sun appears larger.
You can check this illusion in an effective, if undignified, manner. Face away from the setting sun, bend down, and look at it from between your legs. The sun will appear smaller than it did at noon.
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Congressional Fellow Report: Enron, Energy and Cafe
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Senator Carl Levin (D-Mich.) was running a double header today. He was simultaneously chairing the Armed Services Committee hearing and shuttling over to a concurrent Governmental Affairs Committee hearing on the Enron 401(k) disaster. (By the way, did I also mention the TV crew from back home that was following him around to capture “A day in the life of Carl Levin”?)
It was my job to support him on the Enron hearing. In spite of the fact that I had not ever done anything like this previously, the day before I was summarily informed that I would be going solo. And yes, I’ll admit to being a bit nervous. I had had only a couple of days to assemble the briefing notebook and formulate questions—all with only limited notice of who would actually be showing up on the panel. Because Sen. Levin also had to prepare for Armed Services, of course I never had a chance to go over any of the material with him prior to the actual hearing!
Lights, Camera, Action
At the hearing, I sat in the back row behind the various senators on the committee. By the time Sen. Levin could duck out of his other hearing, we were already well underway. Sen. Joe Lieberman (D-Conn.) (Governmental Affairs Chairman) was in the midst of interrogating one of the witnesses. With kleig lights glaring and TV cameras rolling, Sen. Levin walked in, sat down in his chair, swung around towards his staffer (that would be his ION congressional fellow), and proceeded to interrogate me! After asking me a dozen or so questions on the material, he was ready to go. I thought that he came through very well—both at ad lib and, of course, using those questions that I had prepared for him. But what I also found remarkable was that he was able to annotate and digest my briefing book—weighing as much as a small telephone directory—so quickly. His time window had spanned only sometime in between close of business the day prior and that morning of the hearing.
While this hearing was certainly exciting, most of my experiences in Congress so far have been a bit less real time—though probably no less hectic. When I first arrived in Sen. Levin’s office, I spent two months working on Energy—mostly automobile fuel economy (commonly known as “CAFÉ” standards). Just today, after a long and tortuous path, the Senate has passed its Energy bill overwhelmingly.
Sen. Levin sponsored the portion having to do with CAFÉ—the so-called Levin-Bond Amendment on Corporate Average Fuel Economy. CAFÉ happens to be an important issue back home in Michigan with the big three auto companies and workers. Although it certainly has its controversial tradeoffs (mostly related to foreign oil dependence and greenhouse gas emissions), his key amendment passed 62-38—an overwhelming political victory.
It was a fascinating and extraordinary experience to witness the development of this bill up close and first hand. I was even in a position to make a modest contribution to moving this legislation forward, including working with the senator and senior staff to compile its tax credit provisions for hybrid and fuel cell vehicles.
Enron, Enron, Enron
But it is Enron that has really occupied most of my time since January. Sen. Levin chairs the Permanent Subcommittee on Investigations (PSI). This committee has an illustrious past—its first chairman was a certain then-Sen. Harry S. Truman from Missouri who used it to investigate acquisition fraud surrounding the war effort. (Full disclosure: it is also the subcommittee that was used by then-Sen. Joe McCarthy when he was its chairman for his infamous anti-communism hearings.)
Due to its special charter and powerful subpoena privileges, PSI’s objective is to tell the whole story behind what happened at Enron. This in-depth understanding will then serve as a foundation for changing the law, if necessary, so that such a disaster will never occur again.
This is a bipartisan investigation. Although Sen. Levin’s committee staff takes the lead, committee and personal staff from both parties attend all meetings and collaborate. It is a meticulous, comprehensive study emphasizing the study of more than one million subpoenaed documents (and rising) accompanied by interviews with current and former employees of Enron, Arthur Andersen, the infamous partnerships, major financial institutions, and others. This comprehensive groundwork prefaces PSI’s public hearings. In fact, PSI has not yet conducted a single Enron hearing as of this writing.
Having the senator put me on his investigation with a small handful of other very talented and dedicated staffers was certainly a privilege. Although the work may not be as technical as what I thought I was getting into with this fellowship, I am grateful for this opportunity. I think that we have a unique story to tell and a valuable role to play in getting this investigation done correctly. No other investigative body will be in a position to be this comprehensive.
Beyond Expectations
To my surprise, my own background has even proved useful in unraveling some of the puzzles we are encountering. When I departed for Washington, I certainly had no expectation of being part of a team to investigate a major financial scandal. My own technical background is in high-integrity, centimeter-level navigation applied to aircraft landing systems and other heavy (“steel and hydraulics”) machinery in real-time, precision control applications.
A few years ago, I started a company in Silicon Valley to develop some of these markets that could benefit from this new technology. My expectations going into Washington were that I would work in technology policy areas related to civil aviation and the military. In fact, when Enron broke, the office ended up tapping my background in business more so than any other qualification. While the small company that I started may not be of quite the same scale, I don’t have a problem at all with being on the investigation team—it has been a fascinating new and unforeseen experience. But what I believe is most important is that the Enron story affects us all, and we must do everything we can to prevent anything like it from ever happening again.
I’ve been through a few documents so far (personally, I’m up to about 120,000!—many of which are significantly revealing). In addition to examining documents, we also spend a good deal of time meeting with various outside individuals and groups. PSI’s charter is to investigate Enron as a whole, including its outside partnerships, Arthur Andersen, and the Enron board of directors.
I have been studying a class of transactions and partnerships that are yielding significant insight into vulnerabilities in our financial system. Properly presenting this material publicly in a hearing format we believe will be the most effective in leading to corrective measures.
It’s not often that a fellow stumbles into a position where he is suddenly at the heart of a key congressional investigation on the heels of a major international scandal. I’ve seen and learned much more than I ever expected, and yet I don’t even feel like I’ve gotten started yet! There’s much more work to do. Soon we’ll be conducting our first hearings on the matter and getting our findings out in the open.
An Eye Opening Experience
As someone who has spent much of my professional life immersed in navigation technology and technology in general, I have found the environment on "the Hill" an eye-opening experience—especially in my experience helping out on the Energy bill. Here, for better or for worse, pretty much everything is political (i.e., there to serve one’s constituency). If technology can clearly be the means to further one’s political objectives, then it is supported and embraced. Most technologists, on the other hand, tend to see technology itself as the primary goal or purpose. While there is nothing wrong with either of these views, being able to experience this contrast of perspectives so acutely as a fellow in Washington, D.C. is invaluable.
I’d like to express my thanks to the ION for making this experience possible. This is an extraordinary program with an opportunity to work at the heart of significant issues that affect all of us worldwide. I am deeply indebted to the ION for this mind-expanding and truly profound experience. I’d also like to thank the first ION congressional fellow, Phil Ward, for all his help. Although Phil has now headed back to Texas at the completion of his term, he has been a great source of frequent advice and practical suggestions for the fellowship and in helping me get acclimated quickly.
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Portney's Corner: The Long and the Short of Flights
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Two aircraft, a tanker and a bomber, depart the equator at the Greenwich meridian on a true heading of 045º with unlimited fuel and no wind. The tanker maintains a constant true heading of 045º. The bomber with a flight control system that failed immediately after departure continues on its last orientation (straight and level pitch, roll and heading remain fixed) which it maintains for the entire flight.
Assume that the Earth is a perfect sphere and each aircraft completes one natural cycle of its flight path, describe each aircraft’s path and distance traveled.
Note: Since there is no wind, the true heading equals the track flown as there is no drift and the true heading coincides with the track. Ignore the effects of Coriolis force.
Hint: A great circle is the path traced by the intersection of a plane passing through the center of a sphere and the surface of the sphere. It is the shortest distance between two points on a sphere. A rhumb line is the path traced on the surface of the Earth by a craft that maintains a constant track (crossing all meridians at the same angle). It is the longer distance of the two paths discussed between two points on the Earth. The distance (D) of a rhumb line is D = r sec αΔΦ where r is the mean radius (nmi) of the Earth, α is the track angle and ΔΦ is the difference (in degrees) between the departure and terminal latitudes. Assume the Earth to be a perfect sphere.
A. Both the tanker and bomber fly great circle paths for a round-trip distance of 21,614.5 nmi (mean circumference).
B. Both the tanker and bomber fly rhumb line paths for a distance of 7,641.8 nmi.
C. The bomber flies a rhumb line for a distance of 7,641.8 nmi and the tanker flies a great circle for a distance of 21,614.5 nmi (mean circumference)
D. The tanker flies a rhumb line for a distance of 7,641.8 nmi and the bomber flies a great circle for a distance of 21,641.5 nmi (mean circumference).
Since both aircraft depart on the same heading, the reader is forced to differentiate their paths in the light of the flight control failure of the bomber.
The Tanker Path The tanker maintains a constant course of 045º. The path flown is therefore a rhumb line that intersects each successive meridian at the same angle resulting in a loxodromic path which ultimately spirals toward the North Pole. The distance flown is as follows:
D = r sec αΔΦ
where r = mean radius [(2a+b)/3] of the Earth or 3,440.06 nmi (WGS 84)
α = track angle or 045º
ΔΦ = difference in latitude or 90º
Thus D = 3,440.06 nmi x 1.4142 x 90/360 x 2π = 7,641.8 nmi
Note the comparable great circle path approximation between the equator’s intersection with the Greenwich meridian (latitude 0º and longitude 0º) and the North Pole (latitude 90º, longitude undefined) is simply the latitude difference multiplied by 60 nmi/º or 90º x 60 nmi/deg = 5,400 nmi. This illustrates the advantage of the great circle over the rhumb line in distance savings in the most extreme case ~2,242 nmi (about 3.74 hours savings in a jet flying at 600 knots). The great circle path would be straight up the Greenwich meridian from the equator to the North Pole. It is interesting to note that in the higher latitudes, the change in magnetic variation and the convergence of the meridians are a close match which enables a magnetic rhumb line to be closer to a great circle in distance (example flights between Gander and Shannon) than it is to a true rhumb line path.
The Bomber Path The bomber maintains the same track with respect to inertial space. At the instant of flight control failure (flying straight and level with no lateral acceleration control surfaces fixed), the bomber continues its last space orientation and therefore remains in a plane that is always parallel to its moving tangent plane to the Earth immediately below. Thus, the bomber flies a great circle path in a plane always perpendicular to a plane passing through the center of the Earth.
However, the bomber’s track with respect to the Earth’s coordinate system is constantly changing. The natural cycle of the bomber’s flight is one revolution over the Earth with a distance equal to its circumference. The distance flown would be:
Using the formula of:
c = 2πr
and the mean radius of: 3,440.06 nmi,
D = 21,614.5 nmi (mean circumference) or a close approximation:
D = 360° x 60 nmi/º = 21,600 nmi.
It is important to recognize that in order to fly a rhumb line path, the aircraft must maintain a constant course with reference to the Earth’s coordinate system. The aircraft must be continually turning for the aircraft track angle to remain constant as the meridians are continually converging. This is the distinction between the flight paths flown by the two aircraft.
Lindbergh’s Flight Lindbergh’s flight across the Atlantic between New York and Paris in 1927 illustrates the use of short segmented rhumb lines of 100 miles, which were carefully plotted to approximate the great circle path (between the two cities), resulting in a savings of 140 nmi. Lindbergh used a planning chart with a gnomonic projection where a great circle course is obtained by a straight line between departure and termination. He divided the resulting straight line (between New York and Paris) into 100 mile segments and transferred the coordinates of the extremities of these segments to a Mercator chart which he used for his historic flight. Figure 1 illustrates the rhumb line and great circle comparison.
Note: The Earth is an oblate spheroid with a polar radius slightly less than its equatorial radius. Thus, the shortest distance between two points is a geodesic. Very often in practical navigation, this distinction is ignored and the Earth is considered as a perfect sphere. In an inertial navigation system the oblateness of the Earth is recognized.
You can find more of Portney's Ponderables at www.navworld.com.
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Correction to Pondering Portney, Winter 2001-2002 Issue We erroneously printed the wrong version of Joe Portney’s, Demise of the Errant Balloon, in the Winter 2001-2002 issue of the ION Newsletter (Vol. 11.4). The second sentence of the opening paragraph should have read, “The balloon floats due east and over 2,000 yards away from a rifleman.” Many thanks to our members for bringing this to our attention and our sincere apologies to Mr. Portney and our readers for any confusion. |
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From the ION Historian: Book Review - |
The printing press? The internal combustion engine? The automobile? The airplane? The computer? Air conditioning? All of these have been suggested as the greatest invention of the second millennium. But according to acclaimed science writer Amir D. Aczel, author of Fermat’s Last Theorem and now The Riddle of the COMPASS, the magnetic compass is the most important technological invention since the wheel. The long standing riddles that Aczel investigates include these: How did people discover that a magnetic needle, suspended in air or water, could be used to indicate the north? Where did the idea of north, south, east and west originate, and how did mariners learn to use these directions? How did they begin to use the compass for navigation? Who were the first users and what impact on their civilizations did the compass have?
It is the last question that most intrigued the author. He documents definitively that the Chinese invented the magnetic compass before 1040 A.D. Figure 1 illustrates an iron fish suspended in water which was used as magnetic compass according to an authentic Chinese text published in 1044 A.D. Although the first known reference to a magnetic compass in Europe occurred over 150 years later, it was the Italian maritime cities that refined and exploited the use of the compass.
First the Chinese, Later the Italians
Scholars have been able to pin down the date of the institution of the compass in Italy to between 1274 and 1280. It was the Venetians, the dominant Mediterranean commercial power at that time, who most benefited from the new device. The advent of the magnetic compass heralded a shipping revolution in Venice. While after the year 1000 the Venetians began to build larger ships than their small lagoon boats, in the thirteenth and fourteenth centuries they built truly gigantic ships. In the Middle Ages, most ships were of less than 100 tons’ displacement (roughly 80 feet long). The Venetians had a few ships as large as 200 tons, but there was nothing larger afloat. By the end of the thirteenth century, ships as large as 500 tons were being built by the Venetians (by comparison, the Pilgrims’ Mayflower and Columbus’ Santa Maria displaced 180 and 100 tons, respectively). The reason such large ships could be built was that navigation had by then come a long way. In part by virtue of the compass, ships no longer
lost their way in fog or clouds, and precious time no longer was wasted waiting in port for the winter to pass. In the thirteenth century, the Venetian population exceeded 80,000, which made Venice one of the largest cities in medieval Western Europe. Within a century, with the increase in maritime trade and the prosperity it brought, the population of the area of the “seven seas” reached 160,000, with 120,0000 living in the city of Venice itself (for comparison—only Paris, with 100,000 came close to Venice in population).
One of the ironies of history is that the same invention that made Venice great, the magnetic compass, was also a contributor to its eventual downfall. The Great Age of Exploration in the fifteenth century, aided by the wide adaptation of the magnetic compass, opened new markets and trade routes for the nations of Europe. Venice no longer had the virtual monopoly on world commerce it had enjoyed for centuries. It was conquered by Napoleon in 1797.
One riddle that Amir Azcel does not explore deeply is whether, in today’s modern era of complex extraterrestrial, electronic navigation, there is a role for a 1000 year old, simple, earthly invention.
The ION historian has prepared a presentation entitled “Navigation and Man” that chronicles the major contributors to the art and science of navigation. Please contact him at mbm16@psu.edu for further information.
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GNSS AROUND THE GLOBE
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Congratulations California Maritime Academy Award Winners Dr. Jay Christofferson presents the Institute of Navigation awards to David Boudreaux (top right) and to Nathan Foss (bottom right). |
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Section News
ALBERTA SECTION
The Alberta Section was treated to two stimulating presentations at its March 20 meeting. James McLellan, Mike Dodge and Ken King of Eagle Navigation Systems Inc., spoke on “Modern Survey Methods Used In Geophysics.” They addressed the benefits of using GPS versus conventional (optical) survey methods to meet Low Impact Seismic (LIS) environmental requirements.
After their presentation, Dr. Susan Skone from the Department of Geomatics Engineering at the University of Calgary discussed, “The Impact of Solar Maximum on GPS Applications.” Her talk offered an overview of the current solar cycle and major ionospheric effects observed during the recent solar maximum and the resultant degradations in positioning accuracies and receiver tracking performance. The meeting was held at Calgary Technologies Inc.
NEW ENGLAND SECTION
held its March 20 meeting at Dynamics Research Corporation (DRC) in Andover, Mass. A DRC-hosted, “two-chicken” dinner preceded the meeting. Bruce Angus of Northstar Technologies addressed the section on “Integrated GPS, Electronic Charting, Radar, and Automatic identification Systems in Marine Applications.” Angus discussed the current applications and use of integrated marine electronic systems that combine GPS, electronic charting, radar, and automatic identification systems in commercial shipping and recreational boating. He gave an overview of the existing products, from handheld devices to fixed consoles, as well as the legislative and marketing challenges faced by product manufacturers.
Student ION member Vikram Ramanna followed with his presentation of “An Investigation of the Adaptive Temporal Selective Attenuator.” I.R. Progri, Gene Bogdanov, and V.C. Ramanna from the Electrical and Computer Engineering Department of Worchester Polytechnic Institute also contributed to the presentation content. Ramanna is currently pursuing a M.S. in electrical engineering at WPI.
ROCKY MOUNTAIN SECTION
More that 35 people attended the April 18, section meeting at the University of Colorado in Boulder. Section Chair Garth Powell led the meeting with a discussion of local chapter activities and upcoming events, including a Global Positioning System class for gifted and talented students at Russell Middle School on May 6, 2002.
Dr. Penina Axelrad, CU professor of Aerospace Engineering Sciences and chair of the ION Satellite Division, gave an overview of GPS research in Boulder. These included multiple research projects at CU’s Colorado Center for Astrodynamics, and a number of additional projects at other research facilities in Boulder.
Dallas Masters, a Ph.D. student in the CU department of Aerospace Engineering Sciences, gave a presentation entitled “Bistatic GPS Radar Principles and Applications.” He reported on projects he was leading at CU applying the GPS Bistatic Radar both as an aircraft altimeter and in the Soil Mixture Experiment 2002.
The section hopes to meeting later in the year at Schriever AFB to tour the Second Space Operations (2SOPS) GPS operations facilities, and at the U.S. Naval Observatory Alternate Master Clock.
Other goals include continued community navigation and GPS education programs with schools and scouting groups, and possible RMS-ION support in the hosting of the 2SOPS Performance Analysis Working Group, which is contingent upon 2SOPS approval and agreement to hold the PAWG this year.
WASHINGTON D.C. SECTION
On May 1, the Washington section toured the U.S. Coast Guard Navigation Center (NAVCEN) in Alexandria, Va. NAVCEN is the focal point for the civilian community’s access to the Global Positioning System. NAVCEN operates two terrestrial radio navigation systems: the Differential GPS Service, which provides integrity and accuracy augmentation for the NAVSTAR GPS system, and the LORAN-C hyperbolic fix system. NAVCEN also coordinates and manages the Civilian GPS Service Interface Committee that responds to civil sector user needs and the Navigation Information Service that provides current information about DGPS and GPS via the World Wide Web (www.navcen.uscg.gov) and telephone. The charting branch at NAVCEN works in marine information and electronic navigation systems and charts.
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RTCA Corner
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The fifty-eighth meeting of SC-159 was held on April 12 at RTCA. No new documents were presented for approval. The committee received a presentation on Galileo, its funding status and the classes of service to be provided. Working Group activities dominated.
Next Meeting: August 12–16, 2002
Chair: Larry Chesto, Consultant
Vice Chair: George Ligler, PMEI
Program Director: Harold Moses, RTCA, Inc.
Secretary: Young Lee, The MITRE Corporation
WG-1, 3rd Civil Frequency, discussed GPS modernization status, L5 received power, future SBAS L5 signals and the latest from the Galileo program. A review of the draft L5 ICD-GPS-705, dated March 29, 2002, generated a comment matrix.
WG-2, GPS/WAAS, reviewed the current DO-229C and a spreadsheet that contained issues that may be addressed in an evolution to DO-229D.
WG-2A, GPS/GLONASS, continues to monitor GLONASS activity to determine if DO-229 should be updated to include GLONASS. No new information was presented.
WG-2C, GPS/Inertial, continued work to determine how tightly integrated GPS/inertial coasting would help continue navigation in the presence of interference. The goal is to perform at least two independent investigations of what the coasting performance is and to reach a consensus before the August meeting. Another task is to specify requirements and test procedures for SA off GPS/inertial performance. This work is ongoing in two important areas: gravity modeling and ionosphere modeling.
WG-4, GPS/LAAS, primary task is to revise DO-245, LAAS MASPS. The update will be in a few areas: align the CAT I/PVT requirements, provide CAT II/III precision approach requirements and RNAV requirements such as curved/segmented approaches. The current plan calls for completion of a draft by the end of 2002 and obtain SC-159 review/approval in late 2003.
WG-5, Airport Surface Navigation and Surveillance, is keeping current on the status of airport surface requirements. Status reports for international activities, the DFW Program and the Safe Flight 21 were reviewed. The European Air Navigation Planning Group (EANPG) reports forwarding the A-SMGCS Manual to ICAO for processing as a global document. Currently, no international process has been established to review and further develop the manual. NASA and Ohio University presented results of their analysis of the GPS performance during the DFW test program. LAAS and WAAS data was collected during various runway incursion and hold short scenarios. Horizontal accuracy was in the 1-2 meter range, while the vertical accuracy showed a bias of 4-5 meters. Safe Flight 21 test planning for Memphis is continuing. Initial tests will concentrate on ADS-B/TIS-B systems and the interoperability between different manufacturer’s equipment.
WG-6, GPS/Interference, continued work on the GNSS L1 RFI Assessment Report. The revised schedule calls for distribution of the document for final review and comment in July and presentation to SC-159 in August 2002. The WG will continue to revise the L5 RFI Assessment Report through this winter. Presentation of a mature document to SC-159 is scheduled for spring 2003.
Ad Hoc Working Group, JHU/APL RAIM Recommendation, will circulate an updated report for final review and approval at the next SC-159 meeting.
RTCA, Inc. is a private, not-for-profit corporation that develops consensus-based recommendations regarding communications, navigation, surveillance and air traffic management (CNS/ATM) system issues. RTCA functions as a federal advisory committee. Its recommendations are used by the Federal Aviation Administration (FAA) as the basis for policy, program and regulatory decisions, and by the private sector as the basis for development, investment and other business decisions.
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Corporate Profile
A long-term supplier of critical test instrumentation and missile tracking systems for the U.S. Navy’s Fleet Ballistic Missile (FBM) weapons systems, including the Trident submarine. The division is also a leader in Global Positioning Systems (GPS) currently in use on multiple aircraft, cruise missiles and precision guided bombs. In addition, IEC produces ruggedized displays for military and industrial applications, and provides secure communications equipment and services on a quick reaction basis for deployed forces in Eastern Europe.
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L-3 Communications|
New Corporate Members The ION extends a warm welcome to the following new Corporate Members:
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CALENDAR OF EVENTS
September 2002
November 2002
January 2003 |
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All contents (c) Institute of Navigation, Inc. All Rights Reserved.