John Menzies warns on full-year aviation unit profit

* Aviation unit managing director to leave immediately

* Unit's profit hurt by business losses at Heathrow

* Shares (Berlin: DI6.BE - news) fall 19 pct to lowest in more than 3 yrs (Adds analyst comment, details, share price)

By Esha Vaish

Nov 5 (Reuters) - John Menzies Plc (LSE: MNZS.L - news) said full-year profit from its aviation business would be "materially" below expectations and that the unit's managing director would leave the company immediately.

Shares of the Edinburgh-based company plunged about 19 percent in early trading to their lowest in more than three years. The stock was among the biggest losers on the London Stock Exchange.

Craig Smyth, who had led the division of John Menzies responsible for aircraft refuelling, cargo and baggage handling at airports worldwide, resigned in August but the date of his leaving had not previously been announced.

Analysts from Liberum brokerage wrote that Smyth's immediate departure suggested the unit's issues may have been partly "execution-related", though pricing at London's Heathrow airport has also hit business.

The company's aviation business, which also runs VIP lounges and handles ticketing, check-ins and aircraft de-icing, has been affected by the loss of some British Airways business at Heathrow, as well as contract losses in Colombia and lower-than-expected cargo returns in Australia.

John Menzies said these factors would also hurt the aviation unit's results next year - bad news for the company, which has been expanding in aviation support services to shore up profits as dwindling demand has stymied growth of its other main business, magazine and newspaper distribution in the UK.

N+1 Singer analysts cut their full-year group adjusted pretax profit forecast by 10 percent to 43.1 million pounds ($68.8 million) but said they would revise their expectations as new CEO Jeremy Stafford "hones the future strategy".

As part of a management revamp, Stafford last month became the group's first CEO in more than seven years. It had earlier been run by two managing directors, a finance director and a company secretary.

John Menzies' shares were down 19.3 percent at 392.75 pence at 0851 GMT. (1 US dollar = 0.6268 British pound) (Editing by Sunil Nair and Robin Paxton)