Controlled Flight Into Terrain and the enhanced Ground ProximityWarning system

The leading cause of worldwide aviation fatalities comes from inadvertently flying a perfectly operating aircraft into the ground or water. This type of accident is referred to as Controlled Flight Into Terrain (CFIT). Statistics show that introduction of the Ground Proximity Warning System (GPWS) into the scheduled air carrier turbojet fleet has been accompanied by a dramatic drop in the frequency of CFIT accidents. Training aids, videos, checklists, and procedural recommendations have also been produced to aid in CFIT risk reduction. Despite these actions, CFIT worldwide losses continue. Common characteristics of these continued accidents are a lack of installed GPWS or shortcomings of the current GPWS detection algorithms. The Enhanced Ground Proximity Warning Systems have been developed to address these shortcomings, and to provide enhanced situational awareness to the pilots such that CFIT accidents can become a thing of the past     

Theoretical model of electron temperature and electron density: Comparisons with IRI and MSIS

An earlier theoretical model (UW-87) accurately predicted the electron temperature in the daytime F-region but suggested N₂ concentrations significantly greater than the predictions of MSIS-86. This discrepancy is resolved when the model is developed to include the effects of vibrationally excited nitrogen molecules and electronically excited oxygen ions on the F-region recombination rate. The revised model (UW-92) continues to predict electron temperatures close to the layer peak with great accuracy but it is now more closely consistent with MSIS. However, the electron temperatures predicted by this model, which are in close agreement with EISCAT observations, are significantly higher than the values predicted by the international Reference Ionosphere.