GROANS echoed through the Mongolian-bound jet when the pilot announced the flight was being diverted to Irkutsk. But while others moaned, Robert Storey reacted like a seasoned traveller. The author of Lonely Planet books on Mongolia and China pulled out a guide to Russia and began reading about Siberia. ''Almost instantly I was interrupted by a stewardess,'' he recalled. ''She asked if it was a book on Russia. When I said yes, she asked if it had any maps of Irkutsk. When I showed her, she asked to borrow it.'' An astonished Storey watched as the stewardess rushed into the cockpit. ''She didn't give me the book back until after we had landed in Irkutsk,'' he said. ''I still find it hard to believe, but maybe they had no flight maps and used the little map in mybook to find Irkutsk.'' For Storey, this tale had a happy ending. After an uncomfortable overnight stay in the capital of Russian Siberia, he was flown safely to Ulan Bator in Mongolia, the next day. For the families of the Hong Kong residents on the ill-fated Aeroflot flight that crashed en route from Moscow to Hong Kong last week, the story only underlined the question of air safety standards in Russia and the other former Soviet Union states. ''There's been a long-standing concern about the safety record of Russian airlines, along with unanswered questions about the skill and training of their pilots and other personnel,'' one seasoned observer said. ''About the best thing you can say about Russia is that it has opened up, so at least we hear about these crashes,'' added Jim Eckes, managing director of Indoswiss Aviation. However, despite Russia's reforms and commitment to openness, not all aviation accidents in the old Soviet Union are reported. Western observers believe information is often withheld by some former Soviet states, and government concerns about secrecy restrict crash details which involve military flights. But with rebel warfare raging across much of the former Soviet Union and so many undocumented passengers on unregistered flights, arriving at an accurate death tally is no easy task. Wednesday's crash in Siberia of the Aeroflot Moscow to Hong Kong flight in which 75 passengers and crew were killed, raised Russia's aviation death toll so far this year to over 200. The figure may well have already passed Russia's death toll for all of 1993, when 221 people were known to have been killed in 11 commercial airline accidents. But fatalities do not tell the entire story. Accusations of shoddy maintenance, poor service and overbooking linger, despite Aeroflot's battle to improve its image. And there seems little sign of improvement. Last Tuesday, a Russian TU-154 airliner was forced to land in Irkutsk after a fire broke out while en route to China, according to accounts in Russian newspapers. There were no reports of casualties. As recently as last Boxing Day, three dozen people were killed when a Russian plane crashed as it approached Armenia. The Krasnodar Air Enterprise accident is cited by aviation journal, Flight International, as the ''most blatant example'' of the disregard for international aviation standards in Russia and the former Soviet Union. THE ill-fated flight was supposedly carrying cargo. All passengers were loaded illegally and some even carried cans of petrol as luggage. ''Overcrowding is one of the worst problems in Russia,'' said Robert Granger, a spokesman for the United States-based International Airline Passengers Association. The airline safety advocacy group, with 150,000 members worldwide, issues a bi-monthly Safety Alert newsletter. The February issue stated: ''Russian aviation air safety is rapidly deteriorating. Possibly the most dangerous situations of all can be found in the countries along the southern rim of the CIS [Commonwealth of Independent States].'' Mr Granger said a detailed study on the dangers of air travel in Russia and other regions of the former Soviet Union would be issued next month. In it, Russian carriers will be criticised for the quality of all their services, ''but the overcrowding is extremely worrying'', Mr Granger said. Even discounting passenger planes shot down by gunfire in the various regional conflicts, Russia remains a place where ''you take your life in your hands when you fly'', according to one Hong Kong businessman who regularly visits the region. Aeroflot, for its part, has worked hard to improve its service since the enormous communist carrier was deregulated and a host of regional and independent airlines began operation. As in China, the surviving national carrier provides a higher level of service, and better planes, on all its international flights. However, Aeroflot's problems extend far beyond the seating charts. Security is suspect throughout the entire region. Two recent incidents illustrate this. A Tupelov 154 which crashed in Siberia on January 3 was at first believed to have killed all 120 people on board. Later, the death count was amended to include several stowaways. That same month, an Aeroflot flight from London to Moscow was forced to make an emergency landing in Berlin after a windscreen blew out of the cockpit. This incident, and other Aeroflot problems, prompted British Civil Aviation Authority officials to threaten to ban Aeroflot flights unless serious safety concerns were addressed.