* Zegna, Dolce & Gabbana, Versace started four days of shows
* Corneliani opens show with message for missing Missoni scion
* Grey coats dominate at Zegna, Dolce & Gabbana, Burberry
* Italian menswear sales up 1.9 pct in 2012, domestic sales down - SMI (Adds quotes, details from the shows)
MILAN, Jan 12 (Reuters) - Concerns over the fate of fashion executive Vittorio Missoni and prospects for the economy weighed on the opening of Milan's menswear shows, where designers used all shades of grey for their austere 2013 autumn/winter collections.
The founder of menswear maker Corneliani kicked off the first show of the Milan fashion season on Saturday with a message for Missoni, whose plane disappeared off Venezuela a week ago.
"We want to show our solidarity to the Missoni family on the first day of the fashion week," company founder Carlo Alberto Corneliani said on a loudspeaker before the event started.
A small twin-engine aircraft carrying Missoni, 58, his wife Maurizia Castiglioni, another couple and two Venezuelan crew went missing on Jan. 4 after taking off from the Caribbean island resort of Los Roques.
The Missoni group, known for its exuberantly coloured knits featuring bold stripes and zigzags, has decided to go ahead with its show on Sunday, but the family is unlikely to attend.
Media reported on Saturday that the location where the plane disappeared may have been found, but it was not possible to get an immediate comment from Italy's foreign ministry.
Italy's luxury goods industry is set to continue to outperform other sectors this year, according to analysts, helped by the appetite of wealthy Asian shoppers.
But prospects for the economy remain as gloomy as the cloudy skies under which hundreds of fashion critics and buyers rushed to watch the menswear proposals for next winter.
Orders of Italian menswear for the 2013 spring/summer season have fallen 8 percent, Italy's textile and fashion body Sistema Moda Italia (SMI) said.
Over half of domestic menswear manufacturers polled by SMI said they saw no sign of improvement this year, while the remaining 44 percent said they were preparing for deterioration.
FEET ON THE GROUND
An austere elegance reigned on the catwalks on Saturday, where designers like Dolce & Gabbana and Ermenegildo Zegna worked a grey palette for their collections.
Europe is still the biggest market for Italian menswear but sales fell 2.7 percent in France and up to 7 percent in Spain in the first nine months of 2012, SMI said.
"I thought of men who keep their feet on the ground, are rigorous, love clean cuts and precious sartorial details," designer Anna Zegna told reporters in the backstage of the show.
Traditional coats in lightweight and soft "spazzolino", the alpaca fabric launched by Zegna's Agnona brand in the Seventies, were worn over double-breasted suits.
Grey coats returned at glamorous Dolce & Gabbana, where Sicilian boys strutted the catwalk like professional models.
Coats found their natural home at British house Burberry , where creative head Christopher Bailey worked every possible material for his youthful collection.
The fashion houses streamed their shows online to entice a growing number of customers who shop on their smartphones.
Online websites and outlets are the only places in Italy where menswear sales have risen last year, according to SMI.
But this growing divide between virtual and real stores is forcing houses to reinvent their shops to lure back customers.
"The digital world is a very important tool, but it doesn't have to be idealised," Burberry chief executive Angela Ahrendts told Reuters at the show. "We are opening stores too," she said.
The Milan shows, ending on Tuesday, will also include Versace, Armani, Gucci, Ferragamo, Fendi and Prada. ($1 = 0.7568 euros) (Additional reporting by Victoria Bryan; Editing by Jason Webb and Rosalind Russell)