Autolanding a 737 using GPS and Integrity Beacons

Abstract

This paper describes how differential GPS (DGPS) and miniature, low-cost Integrity Beacon pseudolites were used to carry out 110 successful automatic landings of a United Airlines Boeing 737 aircraft. These autopilot-in-the-loop flight tests using GPS Integrity Beacons (low-power, ground-based marker beacon pseudolites placed under the approach path) furnished evidence that GPS can provide the full performance necessary to meet the stringent specifications of Category III. The built-in geometrical redundancy provided by Integrity Beacon ranging is coupled with centimeter-level accuracy to provide the system integrity. This integritycalculated to be better than one part in a billion probability of missed detectionis achieved independently from ground-based monitors using receiver autonomous integrity monitoring @AIM).

Analysis of Iridium-Augmented GPS for Floating Carrier Phase Positioning

“…The Integrity Beacon Landing System (IBLS) devised in the early 1990s was an explicit implementation of this principle for aircraft precision approach and landing [4,5]. GPS signal transmitters serving as pseudo-satellites ('pseudolites') placed on the ground along the airplane's trajectory provided additional ranging sources and a large geometry change as the receiver's downwardlooking antenna flew over the installation.…”

“…GPS signal transmitters serving as pseudo-satellites ('pseudolites') placed on the ground along the airplane's trajectory provided additional ranging sources and a large geometry change as the receiver's downwardlooking antenna flew over the installation. The efficiency of IBLS was demonstrated in 1994 as it enabled 110 successful automatic landings of a Boeing 737 [4] and in 2003 for the high angle-ofattack Extremely Short Takeoff and Landing (ESTOL) of the Navy/Boeing/EADS X-31 aircraft [6]. However, pseudolite placement constraints and off-field operations and maintenance access cost has dampened wider application of the system.…”

Algorithm and Flight Test Results to Exchange Code Noise and Multipath for Biases in Dual Frequency Differential GPS for Precision Approach

“…The literature also documents the performance of many differential and relative GPS architectures in flight tests [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. These serve as points of comparison for the performance of the architecture presented in this paper.…”

Approach service type D evaluation of the DLR GBAS testbed

“…A consortium of Stanford University, Boeing, United Airlines and the US Federal Aviation Administration began development of a satellite-based guidance system that culminated in the successful completion of flight trials in 1994 when a Boeing 737 performed a series of automatic landings based only on GNSS navigation (Cohen et al 1995). Here, a differential GPS (DGPS) system in conjunction with pseudolites (called integrity beacons) provided the necessary accuracy and integrity for guidance all the way to touchdown.…”