The Open Aerospace Engineering Journal, 2011, 4, 11-25 11 1874-1460/11 2011 Bentham Open Open Access Predictive Landing Guidance in Synthetic Vision Displays R.R.D. Arents 1 , J. Groeneweg 1 , C. Borst 2 , M.M. van Paassen 2 and M. Mulder *,2 1 National Aerospace Laboratory NLR, Cockpit & Flight Operations (ATCF) Department, The Netherlands 2 Delft University of Technology, Faculty of Aerospace Engineering, Control and Simulation Section, The Netherlands Abstract: Pilot manual path-following performance with synthetic vision displays can be improved with predictive guidance symbols. Little is known, however, on how these predictive guidance concepts can be applied to the landing flare maneuver. This paper discusses the applicability of 3D predictive guidance in synthetic vision displays during the final phase of the landing. Two types of predictive guidance were examined, the Flight-Path Predictor that indicates the aircraft’s future position a certain time ahead, and the Flight Trajectory Predictor that presents the future trajectory by interpolating a number of sequential predicted positions. A theoretical investigation and an offline simulation were used to optimize the two guidance laws for the manual landing task. A pilot-in-the-loop experiment, conducted in a moving-base flight simulator, indicated that both predictive guidance types investigated support pilots in manual control. The pilot’s ability to determine the correct flare initiation time is improved, and becomes comparable to timing the flare with a more realistic synthetic vision display with textured surfaces. Even though the flare initiation timing was improved by the addition of predictive guidance, the control of the flare after its initiation was not sufficiently supported. As a result, no noticeable improvement in landing performance was found. Keywords: perspective flight-path displays, landing guidance, pilot performance, synthetic vision displays. INTRODUCTION Especially in general aviation, Synthetic Vision Systems (SVS) start to find their way into the cockpit. In an SVS, a synthetic computer-generated image of the world outside the cockpit is presented on a synthetic vision display, considerably improving a pilot’s situation awareness. The artificial view of the outside world, restoring the visual contact with the ground at all times, can be further augmented by presenting the reference trajectory to be followed in 3D perspective, yielding a perspective flight-path display also known as a ‘tunnel-in-the- sky’ [1-3]. As these smaller aircraft are generally not equipped with advanced automatic landing systems, the autoland system, most of the approaches and landings are conducted by the pilot in full manual control of the aircraft motion relative to the target runway. Surprisingly little research has been conducted on whether synthetic vision displays, including the perspective flight-path presentation, can support pilots in manual control during the final phase of the landing. Whereas the navigation and path-following performance has been shown to improve during approach and final approach, the actual landing of the aircraft, i.e., the initiation and control of the flare, has rarely been studied. Given the often poor performance of pilots when landing in a simulator, the landing performance with a comparable artificial instrument, the synthetic vision display, may also be much worse as compared to landing using the natural out-of-the-window visual array. Issues such as the *Address correspondence to this author at the Delft University of Technology, Faculty of Aerospace Engineering, Control and Simulation Section, The Netherlands; Tel: +31 15 278 2094; Fax: +31 15 278 6480; E-mail: M.Mulder@tudelft.nl relatively small size of the synthetic display, the availability and quality of its textures, the choice of its field of view and related issues of ‘conformal angles’ of the presentation might play a role here. The possible effects of safety of mediocre or even bad pilot performance, especially in single pilot operations with small general aviation aircraft, are clear motivations to study pilot landing performance with synthetic instruments. In the development of the perspective flight-path display in the 1980s and 1990s, various display augmentation principles have been developed to improve path-following accuracy [1-5]. The main example is the flight-path predictor (FPP), showing the future position of the aircraft a few seconds ahead in time. This ‘predictive’ display augmentation principle has shown to be very successful in improving manual path-following performance; however, there has been relatively little attention for the landing phase. In this paper we investigate the landing performance of pilots using a synthetic vision display, and also study whether the use of predictive landing guidance can be used to improve performance. The synthetic vision displays studied include a perspective projection of the flight path. Two predictive guidance concepts will be discussed, the above-mentioned flight-path predictor, and the flight- trajectory predictor discussed later. In particular the pilot performance in initiating and controlling the flare will be investigated. The paper is structured as follows. First, the landing flare is discussed in detail, including a summary of its sub-phases, the maneuver itself, and possible strategies to initiate and control the flare. Secondly, the two predictive guidance concepts will be discussed followed by a description of how