RCED-88-118 Microwave Landing Systems

.-- ht8y 198% MICROWAVE LANDING SYSTEMS Additional System Should Not E3e F!t33ctlred unless l3enefits Proven _--- Resources, Community, and Economic Development Division B-226281.2 May 16, 1988 The Honorable William Lehman Chairman, Subcommittee on Transportation Committee on Appropriations House of Representatives Dear Mr. Chairman: This report is in response to your request to conduct continuing reviews of the Federal Aviation Administration’s (FAA) National Airspace System plan. This report addresses FAA’S management of the development and acquisition of a precision approach and landing system, the microwave landing system. As agreed with your office, unless you publically announce its contents earlier, we plan no further distribution of this report until 7 days from the date of this letter. At that time, we will send copies of this report to the Secretary of Transportation; the Administrator, Federal Aviation Administration; and the Director, Office of Management and Budget. Copies are also being made available to other interested parties. This work was performed under the direction of Kenneth M. Mead, Associate Director. Major contributors are listed in appendix VI. Sincerely yours, QmaJ. Dexter Peach Assistant Comptroller General Executive Summw Important parts of our national airspace system (NAS) are the precision Purpose landing systems which allow aircraft equipped with the necessary elec- tronic hardware (avionics) to land in conditions of limited visibility, thereby increasing the time an airport can operate during poor weather. The current precision landing system, the instrument landing system (US), is scheduled to be replaced with the microwave landing system (MLS) as part of the Federal Aviation Administration’s (FAA) ambitious effort to modernize the nation’s air traffic control system-known as the MS plan. The Chairman, Subcommittee on Transportation, House Committee on Appropriations, asked GAO to review FAA'S implementation of the NAS plan. As part of this effort, GAO reviewed the MIS program, addressing the following ob.jectives: . assessthe justification and requirements for a new precision landing system to replace IIS and determine and analyze IZS improvements since MIS was justified, l determine whether FAAhas adequately demonstrated MIS' potential operational and economic benefits, and l determine the reasonableness of FAA’SMW siting strategy. --- Precision landing systems are comprised of (1) ground units located Background adjacent to airport runways and (2) avionics equipment on aircraft. When approaching an airport, a pilot, using the avionics, follows an indicated course and angle of descent down to a point where the runway becomes visible. The standard precision landing system for over 40 years has been the IIS. In the 197Os, the federal government, with the aviation community’s support, selected MIH as the primary precision landing system for mili- tary and civilian use. MIS has also been selected as the international standard to replace 11s. MA plans to spend about $1.6 billion on 1,260 MISS,while the Depart- ment of Defense plans to spend $357 million on 405 MISS. Further, installing MIS avionics on civilian aircraft-a prerequisite for using the ground systems-will cost about $5.1 billion more than using IIS. Installation of thct first of 178 MISS was scheduled by FAA to begin in *January 1986. However, primarily because of software development problems, install&ion is 27 months behind schedule. Page 2 GAO/RCED-W118 MIS FWcurement Executive Summary FAA had planned to buy another 500 MISSearly in fiscal year 1987. How- ever, the Congress denied funds for this purpose for fiscal year 1987 because of MIS development problems. For fiscal year 1988 the Congress denied funds to procure MISS pending operational tests and an implementation strategy review. MIS was justified 19 years ago because of ns’ reliability and precision Results in Brief landing capability limitations. However, through improvements to II& FAA has largely addressed concerns about these limitations, though FAA has not determined how these improvements and air traffic growth, which has been lower than predicted, affect the need for MIS. MIS offers potential operational and economic benefits in cases where IISS cannot be used because of siting or visibility limitations. MIS' spe- cialized approach capabilities and various descent angle features also may increase airport capacity and reduce flight delays. However, FAA has not adequately demonstrated such benefits, nor addressed safety and reliability questions using MIS in challenging operational environments. The Air Transport Association, which represents most major US. airlines, believes there is little incentive for its members to install MLS avionics on their aircraft until ML?' benefits are, adequately demonstrated. Since 1984 FAA has twice changed the locations to receive the first MISS because it has developed new selection criteria for choosing these sites. Principal Findings ILS Is a Much Improved In 1969, when MLSwas first justified, concerns existed about KS’ reliabil- System ity and the limitations on the number of radio channels and frequencies available to it. FAA has generally addressed these concerns. For example, IL% are now more reliable because tube-type systems have been replaced with solid-state systems. Overcoming the problem of radio frequency limitations has included assigning the same radio frequency rather than different frequencies to ILSSat opposite ends of the same runway; this frees frequencies for more ILSS. MIS was also justified because large increases in air traffic volume were forecast. However, this growth has been less than expected, with flights Page3 GAO/RCED-fB-118 MIS Procurement .-- Executive Summary that might have used precision guidance to land in 1980 increasing to only about half what was forecast in 1969. Meanwhile, according to an FAA official, FAA has not determined what air traffic volume warrants using MIS instead of us. FAA still plans to replace IISS with MISS even though it has not reassessed its plan by recognizing (1) IIS improvements and (2) lower than forecast air traffic growth. In the interim, the Air Transport Association believes that 11s meets most of its precision landing system needs. It has recom- mended that FAA retain ILS as the United States’ primary precision landing system, and MIS become the standard secondary system worldwide in airports where 11s cannot meet user needs. MLS Potential &n&its Not MIS offers potential operational and economic benefits. However, these Adequately Demonstrated benefits are contingent on several factors, including the success with which it can be integrated into the actual air traffic control environment. FAA recognized the importance of testing MLS in the airport environments in which it is to be used. However. because of problems and delays, program costs increased and FAA entered production after limited testing of MLS units not built to FAA specifications. Thus, the potential benefits as well as the system’s safety and reliability remain in question. For example, testing special airport approaches made possible with MIS has been conducted only in a nonoperational environment. For fiscal year 1989, PAA requested $20 million to initiate purchasing MISS and develop the avionics necessary to demonstrate MIS' potential benefits in preparation for a second procurement. FAA is also developing plans to test MLSS at Washington’s National Air- port and New York’s LaGuardia Airport. How comprehensive these tests will be has not been determined. ---- FAA’s ML23 Siting Strategy Since 1984, I%A has revised its selection criteria for choosing where MI.& Needs Reassessment will be sited. Initially, the first 172 MISS were to be installed at large and medium airports-defined on the basis of passenger traffic activity- and their connecting airports. FAA revised the locations (increased to 178) because some were not cost-beneficial and some others had higher priorities. Most recently, though, FAA has chosen airports where MIS may provide increased operational benefits; these are selected on the basis of Page 4 GAO/RCED$8118 MLS Procurement - Executive Summary air carriers’ verbal commitments to equip their aircraft with MIS avionics. The results of this method, however, have been questioned by the Department of Transportation’s Inspector General, who found that MIS did not have the amount of user support FAA thought existed. GAO recommends that the Secretary of Transportation require FAA not to Recommendations . proceed with the planned second w procurement unless MIS’ potential operational and economic benefits have been adequately demonstrated. This should include comparing the results of testing MIS in chahenging airport environments to the much improved ILS and recognizing current and expected air traffic growth. Interim actions to be taken are detailed in chapters 4 and 5. ___c____I- GAO discussed the matters in this report with FAA officials and incorpo- Agency Comments rated their comments where appropriate. However, as requested, GAO did not obtain official agency comments on a draft of the report. Page 5 GAO/RCXD&?-118MISProcnrement Contents Executive Summary 2 Chapter 1 10 Introduction Precision Landing Systems 11 International MLS Agreement 15 Management of MLS Program 15 MIS Program Status 16 Objectives, Scope, and Methodology 18 Chapter 2 23 Requirement to ILS Now Able to Better Satisfy Precision Landing System 23 Needs Replace ILS With MU Air Traffic Growth Less

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