Usage Note: Momentarily is widely used in speech to mean “in a moment, shortly,” as in The manager is on another line, but she'll be with you momentarily. Many critics dislike this use, insisting that the adverb should only be used to mean “for a moment,” as in He hesitated momentarily before entering the room. The Usage Panel shows some dissatisfaction with the nontraditional use, but resistance is waning. In our 1988 survey, 59 percent of the Usage Panel accepted the first example above, and in 1999, 68 percent accepted it. Also in 1999, 58 percent of the Panel approved of the vaguer use of momentarily in the sense of “for the time being,” where the length of time is open-ended, as in The file server is momentarily out of order.
Many speakers object to the use of momentarily in the sense of “in a moment" rather than “for a moment", since this is inconsistent with the meaning of momentary; nonetheless, this use is quite common in North America, and is particularly associated with airlines, such as “we will be landing momentarily". In place of momentarily, many speakers prefer the terms presently, soon or the phrase “in a moment", for this sense of “in a moment".