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Title: Prospective sky guides : developing future pilot vision aids
Author: Jump, Michael
ISNI:       0000 0001 2437 0100
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2007
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Airline transport operations are carried out in a wide range of visual and instrument meteorological conditions. For all but the most limiting of degraded visibility situations, the pilot can choose to fly the approach to the airfield and land the aircraft manually. S/he does this using the visual cues available through the cockpit windshield. The answer to the question - how is this achieved may seem rather obvious, but has actually challenged researchers for some time. The optical flow theory of visual perception offers solutions in terms of the way pilots pick up motion from the environment in which they move. In a relatively recent incarnation, flow theory transforms motion into the temporal, time-to-contact parameter, τ, defined as the time to close the motion gap to a surface or object at the instantaneous closure rate. This thesis reports on the development of novel display formats, using τ theory as a basis, for the fixed wing jet transport approach and landing manoeuvres. A simulation model of a generic large jet transport aircraft is constructed and a number of repeatable flight test manoeuvres developed. Using these as a start point, a number of flight test trials are conducted. The first two of these is to establish whether or not coherent τ-based relationships exist for a series of motion gaps identified for each flight test manoeuvre. Here, it is discovered that for the localiser capture, glide slope capture and flare manoeuvre, pilots use constant rate of change of τ (τ̇) guidance strategies to close the motion gaps of interest. The use of such strategies is consistent with the pilots coupling onto the τ-guides that τ theory postulates. This result is consistent with previous work conducted using rotary wing aircraft. Based upon the results obtained, a number of concept displays are developed. First, a two-dimensional lead aircraft concept is developed. Here, the pilot must overlay a prediction of the aircraft position at some near-future time with that of the desired position. Speed cueing is provided by the lead aircraft 'looming' if there is a difference between desired and actual airspeed. Second, a flare command display is developed. It provides a commanded flight path angle to achieve a desired τ̇ of height. Again, the pilot must overlay the actual aircraft flight path with desired. In order that these display designs could be finalised, the values of a number of parameters had to be established. A display development trial was conducted for this purpose. The specific values of interest and their final values were: optimum look-ahead time for a lead aircraft to guide the pilot along a given trajectory was found to be 2 seconds; for the localiser capture manoeuvre, the gap closure τ̇ was set at 0.6 and the gap closure duration fixed at 10 seconds; for the glide slope capture manoeuvre the gap closure τ̇ was also set at 0.6 and the duration at 5 seconds; for the flare command display, the τ̇ commanded was 0.75 and the initiation τ at 3.5 seconds. The novel display formats were tested by comparing them with a conventional head-down primary flight display, a 'state-of-the-art' head up display and a highway-in-the-sky concept. The comparison was performed using objective measurement of actual and desired trajectories and subjective measurement using the NASA display flyability rating scale and the Bedford workload scale. During this testing, the looming cue was found to be insufficient for the purposes of accurate speed control. However, the lead aircraft concept is shown to provide superior trajectory tracking over the alternative display formats in both good and degraded visual environments. The improved performance comes at the expense of slightly higher pilot-perceived workload. The τ-based flare command display is shown to provide landing touchdown performance as least as good as a current state-of-the-art head-up display in both good and degraded visual environments. Based upon the design process followed and the results obtained, a number of conclusions are drawn. The most important is that τ-based motion gap closure strategies are a fundamental means by which pilots guide aircraft through the environment. As such, the future display designers should incorporate the methods and approach discussed in this thesis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral