Perry Simon, the senior exec within NBC Entertainment behind Warren Littlefield, is leaving his post as exec VP of primetime programs and entering into a non-exclusive production arrangement with the network and its in-house division, NBC Prods.No replacement has as yet been named, but sources say NBC West Coast president Don Ohlmeyer’s first choice is Dan McDermott, senior VP of current programs & specials at Fox Broadcasting Co., who currently remains under contract to the program service. NBC declined comment on a replacement, and McDermott — who’s been on a fast track at Fox, currently second in its programming wing behind Fox Entertainment Group chief Sandy Grushow — couldn’t be reached. A 13-year NBC veteran, Simon has for some time been expected to vacate his exec perch to pursue production through his involvement with “Great Escapes,” an umbrella title for NBCP primetime serials that Simon will now oversee. The first , “Trade Winds,” will premiere Aug. 27, followed Oct. 1 by “The Secrets of Lake Success.” Simon noted that the production route is “something I’ve been thinking about for awhile” and that the end of development season, other changes at NBC and a window in his contract made this “a natural time … (to) see the other world of opportunities out there.” His exit represents the second major exec to do so since Ohlmeyer took over the West Coast operation in February, following the replacement of longform programming senior VP Ruth Slawson (a position that reported to Simon) with former Lorimar exec Lindy DeKoven in March. NBC also confirmed earlier this week that two directors in the movie & miniseries department, Mindy Green and Michael Tenzer, were leaving (Daily Variety, July 13). Simon has ridden the primetime elevator at NBC, joining the Peacock web as a comedy programming associate in 1980 — when the web was in third place — and climbing the ranks under Brandon Tartikoff and Littlefield even as NBC broke out of the cellar to enjoy a six-year ratings reign, from 1985 -86 through the ’90-91 campaign. NBC slump With a number of its hits gone, however, NBC slumped back into third place last season, spurring conjecture about personnel changes and thus prompting scant surprise about Simon’s departure. Simon assumed his most recent position in July 1990, overseeing all aspects of the primetime schedule, including movies and series. Before that he held VP positions in creative affairs at NBC Prods. (1984) and then at NBC Entertainment in comedy development (’85) and drama programs (’86). Involvement in the “Great Escapes” franchise “gets me off and running” in the production area, Simon said, adding that his deal is non-exclusive at this point because he wants to leave various avenues open to him. “Great Escapes” represents a new way to approach the serial genre, he added, by testing concepts while creating viable stand-alone assets the network can own, merchandise and distribute overseas. During his tenure Simon’s been involved with such series as “The Golden Girls ,”"Law & Order” and “The Fresh Prince of Bel-Air” and personally spearheaded the creation of the fall Paramount sitcom “The Mommies,” based on the female comedy duo of the same name.