** John Menzies plummet 20.9 pct to feature assecond-largest pct loser on LSE after warns FY aviation unitprofit will be "materially" below consensus.
** Says unit's managing director Craig Smyth will leaveimmediately.
** John Menzies' stock falls to more than 4-yr low of 385pence, marking its steepest intra-day fall since November 2008.
** Co, whose interests are split between aviation servicesbusiness and print distribution business, blames loss of someBritish Airways business at Heathrow, contract lossesin Colombia and lower-than-expected cargo returns in Australiafor warning.
** Liberum says Smyth's immediate departure suggested theaviation unit's issues may have been partly "execution-related".
** He slashes 2014 EPS forecast by 13 pct and cuts targetprice to 600 pence from 730 pence.
(RM:esha.vaish.thomsonreuters.com@reuters.net)