SubscribeIn response to a White House Initiative to reduce aviation accidents, NASA formed the Aviation Safety Program (AvSP) in 1997.
The seven-year program was tasked to reduce aviation accident rates by 80% by 2007 and by 90% by 2017. Accident and incident reports were analyzed to focus efforts on areas of highest return. These studies showed that 13% of all weather-related accidents were due to airframe icing. To address the icing hazard, NASA has developed a number of tools to supplement pilot training.
These tools have included educational and training videos and computer-based training CD-ROMs. NASA wanted an additional tool to expand pilot training methods to avoid icing-related accidents, consequently, the NASA Glenn Research Center tasked Bihrle Applied Research Inc. to develop an Ice Contamination Effects Flight Training Device (ICEFTD).
The goal was for the ICEFTD to provide pilots a pre-exposure to the adverse effects of icing on airplane performance and stability and control. This device was to also serve as a tool for initial and recurrent pilot training to provide awareness of the consequences of an icing encounter as well as the knowledge of how to best manage potential adverse maneuvers that may result from icing-induced loss of control.
NASA chose the DeHavilland Twin Otter as the initial airplane to model for the ICEFTD because it is their Icing Research Airplane and they had considerable experience and flight records that would be useful in the modeling and validation efforts.
The first stages of the program involved collection of wind tunnel data to be used for the simulation databases. Databases were developed for three conditions: The baseline, un-iced airplane, tail-plane icing alone, and complete airplane icing on all of the flight surfaces. Related tests at Wichita State University had examined the ability to measure icing effects using sub-scale models at low Reynolds numbers and the use of equivalent, simpler, ice shapes.
The lessons learned from those tests were used to gather the required data at BAR’s LAMP wind tunnel facility using the multi-purpose dynamic test rig and a single wind tunnel model to gather all of the static and dynamic (rotational and oscillatory) data required for the modeling effort.
BAR engineers used the data from the LAMP tests to develop comprehensive non-linear flight models of the un-iced and iced airplanes installed in the D-SixÒ simulation environment. The numerous analytical tools in this flight model host permitted the rapid implementation and validation of the models for this effort. The model development featured a rigorous validation of the basic Twin Otter flight model, beyond FAA FTD requirements, culminating in piloted evaluation of all model configurations using NASA test pilots.
Following the successful math model development and validation effort, the actual flight-training device was developed. Because tail-plane icing can cause significant yoke force cues near tail stall with the Twin Otter’s reversible control system (over 100lbs pull force!), a high fidelity longitudinal force loader system was a prime requirement for the ICEFTD. D-Six’s Input/Output Device (IOD) interface enabled the simple and direct integration of a high capacity Fokker stick loader.
The device has a full set of representative pilot control input devices, basic flight instrument and ILS displays suitable for landing tasks, triple screen out-the-window graphics, and an interactive instructor station. It is also designed to be portable with wheels for transport and sized to fit through an office doorway so it can be easily taken on the road to off-site training venues.
A training curriculum has been developed for the ICEFTD to familiarize the training pilot with the basic flight characteristics of the Twin Otter in no-ice and fully iced configurations, so that the pilot can compare and contrast the changes in stall and handling characteristics. Additionally, a scenario-based lesson is used to demonstrate icing effects during the approach to landing segment of a flight.
This device will be used in pilot workshops to demonstrate the cues to recognize iced airplane handling qualities, and the recovery techniques should a handling anomaly occur. As an example, it was recently successfully utilized during an In-flight Icing and Its Effects on Aircraft Handling Characteristics short course taught at the University of Tennessee Space Institute (UTSI) at Tullahoma, Tenn.
For this course, the students had the opportunity to fly both the ICEFTD and UTSI’s variable stability airplane as part of their training. Assistant Professor Richard Ranaudo, the course instructor, commenting on the complimentary nature of the ICEFTD and the airplane for this course, said,
“The opportunity to train and prepare people in the simulator made the flight much more productive. The course attendees really enjoyed the opportunity to get “hands-on” training, which they felt was a real strong point in the curriculum. In addition, the simulator was able to do things the airplane couldn’t, like replicate the tail stall, and provide control system feedback.”
