Encounters with mountain wave activity by aircraft are often uneventful, at times a nuisance, but occasionally can be a significant safety hazard. In extreme cases the results have been significant altitude deviations, passenger/flight attendant injury and/or aircraft airframe damage.

This article will briefly review the current and past efforts in forecasting mountain wave activity and the associated turbulence. It will further focus on the current forecasting efforts by the National Center for Atmospheric Research (NCAR) and on the current Northwest Airlines operational forecasting and avoidance procedures.

Status of the current verification methods will also be described as well as prospects for future avoidance needs and verification methods, especially from the perspective of the 2004 planned implementation in the domestic US of Reduced Vertical Separation Minimum (RVSM).