Aircraft Hazards

USNRC Standard Review Plan, Section 3.5.1.6, Aircraft Hazards, U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation, September 1975. 

Chelapati, C. V., Kennedy, R. P., and Wall, I. B. Probabilistic assessment of aircraft hazard for nuclear power plants, Nuclear Engineering and Design, Vol. 19, 1972, pp. 333-364. 

Wall, I. B. and Augensteifl, R. C. Probabilistic assessment of aircraft hazard to a nuclear power plant -1, Transactions of the American Nuclear Sodety, Vol. 13, 1970, p. 217. 

Corrosion protection is indispensable, especially concerning certain vulnerable parts of the aircraft such as the combustion chamber and turbine. The potential hazards are linked to the presence of sulfur in various forms mercaptans, hydrogen sulfide, free sulfur, and sulfides. 

The presence of naturally occurring ozone in the lower stratosphere creates a potential hazard for passengers and crew members of high flying aircraft (163,164). Ozone in the inlet air to the aircraft cabin, which can reach 1.2 ppm, is destroyed catalyticaHy. 

Hazards Following Ground Deicing and Ground Operations in Conditions Conductive to Aircraft Icing," FAA Advisory Circular, AC 20-117, Federal Aviation Administration, Washington, D.C., Dec. 17, 1982. 

These materials are developed from the polyetherimides introduced by General Electric (see also Section 18.14.2). At the time of writing one grade, Ultem Siltem STM 1500, is being offered. It is of particular interest as a material for wire and cable insulation, as it not only has excellent flame resistance coupled with low smoke generation but also avoids possible toxic and corrosion hazards of halogenated polymers. This can be of importance where there are possible escape problems in the event of a fire, such as in tunnels, aircraft and marine (particularly submarine) vessels. 

Some nitric acid had to be flown from the U.S. to the UK. Several U.S. regulations were broken the acid was packed in glass bottles instead of metal ones and was surrounded by sawdust instead of nonflammable material, and the boxes containing the bottles were not labeled as hazardous or marked This Side Up. The boxes were therefore loaded into the cargo aircraft on their sides, and the bottles leaked. Smoke entered the flight deck, and the crew decided to land, but while doing so the plane crashed, probably as the result of poor visibility on the flight deck, and the crew was killed. It is not clear why a common material of commerce had to be flown across the Atlantic [5]. 

In general, tlie carriage of hazardous materials does not appear to be a significant cause of, or aggravating factor in, aircraft accidents. However, improperly packed and loaded nitric acid was declared tlie probable cause of a cargo jet crash at Boston in 1973, in which tliree crewmen died,"... 

The incidence of aircraft impacts may be significantly higher in certain areas (e g., in the vicinity or airports). The aircraft crash hazard is site specific and tlie failure is strongly dependent on the kinetic energy of tlie aircraft. Two types of data are needed to analyze for aircraft impact the aircraft crash rate in tlie site vicinity (per unit area per year) and tlie effective target area of tlie vulnerable item. Crash rates for different categories of aircraft can be obtained from state and national autliorities (e.g., FAA). The proximity of the site to airfields must be taken into account because crashes are much more frequent witliin a radius of approximately 3 miles. 

Safety Considerations. High-power lasers raise a number of safety issues. There are the flammability and the toxicity of dye solutions. Most importantly, the eye hazards of laser radiation require careful shielding of the beam, and interlocks that restrict access to the laser room and to the dome. The laser could also dazzle aircraft pilots if they look directly down the beam. It is therefore necessary to close a shutter in the beam when a plane comes too close, either manually by human spotters, or automatically by use of radar, thermal IR or CCD cameras. Care must also be taken to avoid hitting overhead satellites in the case of pulsed or high power laser systems. 

For civilian aircraft the facility for rapid starting is not important and cartridge operation is not often employed, particularly because it involves storing and handling explosives, even though the hazards of these explosives are those of fire and not of detonation. For military purposes, however, particularly for fighter aircraft which are best scattered on an airfield, a rapid start is of considerable importance. Therefore cartridge operated starters are much used for these aeroplanes. In Britain, development has been essentially with propellants based on ballistite, namely double base propellants of the solventless type, whereas in the United States composite propellants based on ammonium nitrate have proved more popular. 

General Considerations 1 Location of people relative to the unit 2 Location of critical systems 3 Dominant wind direction 4 Climate and weather extremes earthquake, flooding, windstorms 5 Site topography 6 External hazards or threats (fire/explosion/toxic release from nearby process or facility aircraft subsidence sabotage) 7 Traffic flow patterns and clearances from process vessels and lines 8 Security and reliability of all critical feeds and utilities 9 Command center and alternate command center locations 10 Evacuation routes, emergency exits, safe rally spots... 

Hazard identification can be performed independent of risk assessment. However, the best result is obtained if they are done together. One outcome is that hazards of low probability and minimal consequences are identified and addressed with the result that the process is gold-plated. This means that potentially unnecessary and expensive safety equipment and procedures are implemented. For instance, flying aircraft and tornadoes are hazards to a chemical plant. What are the chances of their occurrence, and what should be done about them For most facilities the probability of these hazards is small No steps are required for prevention. Likewise, hazards with reasonable probability but minimal consequences are sometimes also neglected. 

The helidecks of offshore facilities are usually provided at the highest portion of the offshore installation for avoidance of obstructions during aircraft maneuvering and available space. As a result the roof of the accommodation is typically selected. The location also facilitates evacuation of personnel from installation by helicopter due to its proximity to the highest concentration of personnel. This enhances one of the avenues of escape from the installation but also exposes the accommodation to several hazards. The accommodation becomes subject to the hazards of helicopter crashes, fuel spillages, and incidental helicopter fuel storage and transfer facilities. 

Transportation by vessel, aircraft, tank truck, tank car, or other vehicle or terminal facilities used exclusively to transfer hazardous liquids between such modes of transportation. 

Barnard K, Gordon D. 1991. Sunken vessels and aircraft containing hazardous materials in Puget Sound. Environmental Protection Agency. Seattle, WA. 

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