Australians need to be on alert about the possibility of terrorist incidents involving travel around the world after MH17 was shot down over the Ukraine last year and it appears likely a bomb brought down a Russian airliner over Egypt's Sinai Peninsula on Saturday, says former Air Chief Marshall Angus Houston.
"We live in a much more dangerous world now and we all need to be alert to the fact that when we travel there are going to be terrorist incidents around the world," he said in a speech to newly retired Qantas pilots on Thursday evening in Sydney. "There are going to be serious miscalculations around the world. We need to be on our guard for those." 
Mr Houston, who oversaw efforts to find MH370 and the recovery efforts in the wake of the MH17 crash, said he didn't subscribe to the theory that Russia's Metrojet flight 9268 was a result of poor repairs after the A321 aircraft's tail was damaged 14 years ago.
"I think it is much more likely that somebody got a bomb on the aircraft," he said of the crash that killed all 224 passengers and crew on board. "We'll wait and see what the investigation reveals."
UK Prime Minister David Cameron on Thursday also said it was "more likely than not a terrorist bomb" had brought down the airliner.
Mr Houston said airlines also needed to remain alert about the possibility of aircraft being shot down following the MH17 experience over the Ukraine last year, which killed all 298 people on board, including 38 Australian citizens and residents. Mr Houston said he had done some research on the internet and found over the last 40 years, on average a commercial aircraft had been shot down about once every two years.
"We just aren't getting the message," he said. "I know Qantas is an airline that puts an awful lot of priority on security and checking the routes. In fact I know that personally from when I was organising potential evacuations during the Gulf War. I was talking to the then-Qantas chief pilot. He let me know in no uncertain terms, 'I'm not going anywhere where there are any of those bloody MiGs [missiles].' That is the right attitude. We can't be casual about this."
Mr Houston said war zones existed all over the world at the moment and the prime responsibility of an airline was to ensure all of those war zones were avoided.
Qantas had not been flying over the part of eastern Ukraine where MH17 was shot down in large part because it changed its flight paths in 2013 when it switched its European hub from Singapore to Dubai.
But Qantas last month said it was still flying over northern Iran after the European Aviation Safety Agency alerted airlines that Russian warships had been firing low-altitude long-range missiles into Syria that could cross under their flight paths. Some other carriers, including Malaysia Airlines and Cathay Pacific, decided to stop flying over that area as a result.
At the time, Qantas chief executive Alan Joyce said if the situation in the area became problematic, the airline would stop flying aircraft in that airspace, reminding passengers of the carrier's 95-year reputation for safety.
A Qantas spokesman this week said the airline did not fly over Sinai.