SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 19 - SEPTEMBER 23, 2005

06 AVIONICS AND AIRCRAFT INSTRUMENTATION
Includes all avionics systems, cockpit and cabin display devices, and flight instruments intended for use in aircraft.

For related information see also 04 Aircraft Communications and Navigation; 08 Aircraft Stability and Control; 19 Spacecraft Instrumentation and Astrionics; and 35 Instrumentation and Photography.

20050214782 Civil Aerospace Medical Inst., Oklahoma City, OK, USA

Pilot Willingness to Take Off Into Marginal Weather, Part 2, Antecedent Overfitting with Forward Stepwise Logistic Regression

Knecht, William R.; August 2005; 17 pp.; In English Contract(s)/Grant(s): FAA-AM-HRR-522-04 Report No.(s): DOT/FAA/AM-05/15-Pt-2; No Copyright; Avail: CASI; A03, Hardcopy

Adverse weather is the leading cause of fatalities in general aviation (GA). In prior research, influences of ground visibility, cloud ceiling height, financial incentive, and personality were tested on 60 GA pilots willingness to take off into simulated adverse weather. Results suggested that pilots did not see ‘weather’ as a monolithic cognitive construct but, rather, as an interaction between its separate factors. However, methodological issues arose during the use of logistic regression in modeling the effect of 60+ candidate predictors on the outcome variable of takeoff into adverse weather. It was found quite possible to obtain false ‘significance’ for models comprised merely of random numbers, even when the number of model predictors was limited to a conventional 1/10. Therefore, Monte Carlo simulations were used to derive unbiased estimates of model significance and R(sup 2) values. Research in correction for this case/candidate predictor ratio effect is relatively new and noteworthy, particularly in the social sciences. It was given the name ‘antecedent overfitting’ to contrast with the more commonly known ‘postcedent’ type, which is based on a small case/model predictor ratio. Author

Cloud Height Indicators; Incentives; Personality; Takeoff; Visibility

20050214816 NASA Glenn Research Center, Cleveland, OH, USA

Fiber-Optic Network Architectures for Onboard Avionics Applications Investigated

Nguyen, Hung D.; Ngo, Duc H.; Research and Technology 2002; March 2003; 4 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy

This project is part of a study within the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Center. The main focus of the program is the improvement of air transportation, with particular emphasis on air transportation safety.

Current and future advances in digital data communications between an aircraft and the outside world will require high-bandwidth onboard communication networks. Radiofrequency (RF) systems, with their interconnection network based on coaxial cables and waveguides, increase the complexity of communication systems onboard modern civil and military aircraft with respect to weight, power consumption, and safety. In addition, safety and reliability concerns from electromagnetic interference between the RF components embedded in these communication systems exist. A simple, reliable, and lightweight network that is free from the effects of electromagnetic interference and capable of supporting the broadband communications needs of future onboard digital avionics systems cannot be easily implemented using existing coaxial cable-based systems. Fiber-optical communication systems can meet all these challenges of modern avionics applications in an efficient, cost-effective manner.

The objective of this project is to present a number of optical network architectures for onboard RF signal distribution. Because of the emergence of a number of digital avionics devices requiring high-bandwidth connectivity, fiber-optic RF networks onboard modern aircraft will play a vital role in ensuring a low-noise, highly reliable RF communication system. Two approaches are being used for network architectures for aircraft onboard fiber-optic distribution systems: a hybrid RF-optical network and an all-optical wavelength division multiplexing (WDM) network. Derived from text

Avionics; Fiber Optics; Onboard Equipment; Communication Networks; Architecture (Computers)

Source: NASA.