alert phase

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alert phase (ALERFA)

A phase that begins when apprehension exists about the safety of an aircraft and its occupants, after the uncertainty phase, and a communications search has failed to reveal any news of the aircraft; or an aircraft has been cleared to land and fails to land within 5 min after the estimated time of landing and communication has not been reestablished with the aircraft; or information has been received that indicates that the operating efficiency of the aircraft has been impaired but not to the extent that a forced landing is likely. The code word used to indicate this phase is ALERFA.
References in periodicals archive ?
However, the WHO has yet not caused the pandemic alert phase.
Experts say more information is needed before making a decision on a possible change to the WHO's pandemic alert phase, which is currently at level three on a scale of one to six.
I began to gain this experience and develop these processes when the 1-338th Training Support Battalion sent me to assist the 829th Engineer Team during the alert phase of its preparation for OIF 1 in February 2003.
In response to a question on pandemic alert phase change, Dr Chan explained that the definition of WHOs influenza preparedness phases was developed against backdrop of H5N1 avian flu.
The WHO's graded alert phases for influenza pandemics may imply but do not take into account the severity (as measured by deaths) of the pandemic.
The other counties are in normal or alert phases, with the trend generally being either stable or improving.