In earlier studies by Fletcher [Acustica 34, 224–233 (1976)], Nolle [J. Acoust. Soc. Am. 66, 1612–1626 (1979)], and Angster and Miklos [Proc. 13th Int. Conf. on Acoust., Vol. 3, 99–101 (1989)] crucial parameters determining the transient behavior of a flue organ pipe have been identified. In particular the jet width to mouth height ratio, the labium position relative to the jet center line, the size of the ears, and the steepness of the supply pressure rise appeared to be very important. It is interesting to relate the effect of these parameters to four fundamentally different sound production processes that occur successively in the course of the transient: (a) the variable volume flux through the flue as a consequence of the supply pressure rise, (b) the impulsive vortex shedding occurring when the jet hits the labium for the first time, (c) the jet oscillation controlled by an edge-tone feedback mechanism (Biot–Savart induction), and (d) the jet oscillation controlled by the acoustical response of the pipe (pipe tone). After a discussion, based on flow visualization and internal pressure measurements, a simplified model is presented. The model assumes that the transient is dominated by the variable volume flux (a) and the acoustical response of the pipe (d). The jet oscillation and jet–labium interaction are described with a modified version of Fletcher’s intuitive theory.