Reliability Environments

The reliability figure is affected by the environment, especially the temperature surrounding the product, which accelerates the degradation of parts.​

MIL-HDBK-217 Environments

Ground, Benign


Nonmobile, temperature and humidity controlled environments readily accessible to maintenance; includes laboratory instruments and test equipment, medical electronic equipment, business and scientific computer complexes, and missiles and support equipment in ground silos.

Ground, Fixed


Moderately controlled environments such as installation in permanent racks with adequate cooling air and possible installation in unheated building; includes permanent installation of air traffic control radar and communications facilities.

Ground, Mobile


Equipment installed on wheeled or tracked vehicles and equipment manually transported; includes tactical missile ground support equipment, mobile communication equipment, tactical fire direction systems, handheld communications equipment, laser designations and range finders.

Naval, Sheltered


Includes sheltered or below deck conditions on surface ships and equipment installed in submarines.

Naval, Unsheltered


Unprotected surface shipborne equipment exposed to weather conditions and equipment immersed in salt water. Includes sonar equipment and equipment installed on hydrofoil vessels.

Airborne, Inhabited, Cargo


Typical conditions in cargo compartments, which can be occupied by an aircrew. Environment extremes of pressure, temperature, shock and vibration are minimal. Examples include long mission aircraft such as the C130, C5, B52 and C141. This category also applies to inhabited areas in lower performance smaller aircraft as the T38.

Airborne, Inhabited, Fighter


Same as AIC but installed on high performance aircraft such as fighters and interceptors. Examples include the F15, F16, F111, F/A18 and A10 aircraft.

Airborne, Uninhabited, Cargo


Environmentally uncontrolled areas, which cannot be inhabited by an aircraft, crew during flight. Environmental extremes of pressure, temperature and shock may be severe. Examples include uninhabited areas pf long mission aircraft such as the C130, C5, B52 and C141. This category also applies to uninhabited areas pf lower performance smaller aircraft such as the T38.

Airborne, Uninhabited, Fighter


Same as AUC but installed on high performance aircraft such as fighters and interceptors. Examples include the F15, F16, F111, and A10 aircraft.

Airborne, Rotary Winged


Equipment installed on helicopters. Applies to both internally and externally mounted equipment such as laser designators, fire control systems, and communications equipment.

Space, Flight


Earth orbital. Approaches benign ground conditions. Vehicles neither under powered flight nor in atmospheric reentry; include satellites and shuttles.

Missile, Flight


Conditions related to powered flight or air breathing missiles, cruise missiles, and missiles in unpowered free flight.

Missile, Launch


Severe conditions related to missile launch (air, ground, and sea), space vehicle boost into orbit, and vehicle re-entry and landing by parachute. Also applies to solid rocket motor propulsion powered flight, and torpedo and missile launch from submarines.

Cannon, Launch


Extremely severe conditions related to canon launching of 155mm and 5 inch guided projectiles. Conditions apply to the projectile from launch to target impact.

TELCORDIA SR-332 Environments

Ground, Fixed, Controlled


Nearly zero environmental stress with optimum engineering operation and maintenance. Typical applications are central office, environmentally controlled vaults, environmentally controlled remote shelters, and environmentally controlled customer premise areas.

Ground, Fixed, Uncontrolled


Some environmental stress with limited maintenance. Typical applications are manholes, poles, remote terminals, customer premise areas subject to shock, vibration, temperature, or atmospheric variations.

Ground, Mobile (both vehicular mounted and portable)


Conditions more severe than Gf , mostly for shock and vibration. More maintenance limited and susceptible to operator abuse. Typical applications are mobile telephone, portable operating equipment, and test equipment.

Airborne, Commercial


Conditions more severe than for Gf, mostly for pressure, temperature, shock, and vibration. In addition, the application is more maintenance limited than for Gf . Typical applications are in the passenger compartment of commercial aircraft.

Spacebased, Commercial


Low earth orbit. Conditions as for AC, but with no maintenance. Typical applications are commercial communication satellites.

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