Aircraft at risk from ice

 It's no surprise to most people that icing can bring down an aircraft. Yet few realize just how little ice is needed.
 On the 9th July 2016 a modern airbus with 156 people on board suffered a serious incident from ice. 
 While flying at 37.000 feet both the aircraft main airspeed indicators failed from ice blockage, this despite no ice warning and the sensors being heated. Without being able to judge the correct speed the aircraft can get into a stall. The pilots in this case descended and the ice melted.
 The cause was identified to be the pitot tube suffering icing. Despite all modern tech an aircraft main speed indicator works the same way as a spitfire. Basically a tube (pitot tube) sticks out the front of the aircraft and goes to what is essentially a barometer another tube goes from this out the side of the aircraft (the static vent) the air pressure difference between the two is what gives the airspeed.
 If either of the two tubes ices up the pressure will be wrong. Both pitot tubes are heated to try to prevent this, not all static vents are heated though. In this case it's thought large floating ice crystals got inside the pitot tube and partially blocked them.
 There have been quite a number of fatal accident caused by just this problem, and at least one caused by tape being put of the static vent while an aircraft was cleaned and not removed.
 So next time you fly on holiday keep in mind less ice than you have in your after dinner gin and tonic can bring the aircraft down.
 Sleep well.....