APAn AirAsia Boeing 737 taxis past a Malaysia Airlines Boeing 747 at Kuala Lumpur International Airport.AirAsia Flight QZ8501 disappeared about 45 minutes after takeoff.
Malyasia Arlines MH370, which vanished without a trace earlier this year, also went down well after it had left the runway and entered the "cruise" phase of flight.
Another Malaysia Arlines flight, MH17, was lost over Ukraine in July, presumable shot down by a missile. It, too, was at cruise altitude, but obviously the circumstances of the disaster were far different from those of QZ8501 and MH370.
Crashes when jetliners are at cruising altitude are rare. The riskiest times of any commercial airline flight are during takeoff and landing. Typically, the worst passengers can expect when cruising is some turbulence.
This is from Boeing's own FAQ on the topic of safety (AirAsia flight was actually an Airbus A320, but the safety statistics apply to all jumbo jet manufacturers):
Some parts are statistically riskier than others although none are anywhere near as risky as many of the other things people regularly do, like drive a car. Airplane travel consists of three phases:
Takeoff and climb.
Cruise
Descent, approach and landing.
Looking at accident rates for each phase, cruise is the safest part of flying. Only about 8 percent of all accidents occur during this phase. Approximately 30 percent of all fatal accidents occur during takeoff and climb. Nearly 50 percent of fatal accidents occur during descent, approach and landing. (Note: The remaining 12 percent of fatal accidents occur during non-flight phases including taxi, passenger boarding, etc.)
Because so few accidents occur during cruise, long flights are no riskier than short ones.
From the perspective of aviation experts, this is what's most perplexing about both the MH 370 and QZ 8501 incidents: they happened when accidents aren't supposed to occur.