The following are just some of the many incidents which have been caused either directly or indirectly by Pitot blockage or other pitot / static anomaly. Mostly benign, all costly to the operator, and some catastrophic. ; (Various online sources)
1st December 1974 - Northwest Airlines Flight 6231. Boeing 727 Pitot probes succumbed to atmospheric icing, subsequent loss of reliable air speed data caused the flight crew to lose control and crashed North West of JFK international airport.
6th February 1996 - Birgenair Flight 301 crashed into the sea shortly after takeoff due to unreliable air speed indication. The suspected cause was mud dawber wasp infestation of one of the Pitot probes.
2nd October 1996 - Aeroperu Flight 603 crashed due to unreliable air speed / altitude data having been caused by masking tape covering the ports. This should have been removed after the aircraft was cleaned and waxed.
12th May 2005 - A Midwest Boeing 717-200 suffered temporary loss of control after the crew responded incorrectly to ice build up on the Pitot probes.
19th March 2006 - A Qantas Airbus A300-303 Pilot in command rejected take off after a significant discrepancy was noticed between airspeed indicators. The heavy braking and heat build up caused the tyres' fuse plugs to blow out.
23rd February 2008 - B2 Spirit Bomber crashed in Guam after moisture build up on three of the 24 air pressure sensors caused inaccurate data to reach the flight computer. The flight crew believed they were rotating at the correct speed of 140knts when in fact the speed was 10knts slower. The data also caused incorrect pitch information. The aircraft stalled and veered to the left.
28th January 2009 - A Boeing B752 Astraeus Airlines being operated for Ghana Airways en-route Northern Ghana suffered temporary loss of control being caused by uncertainty regarding the presented air speed. A discrepancy was noticed during the take off roll but the pilot in command decided to continue and deal with the situation later on.
1st June 2009 - Air France Flight AF447 Airbus A330 from Rio de janeiro to Paris exited controlled flight and crashed into the sea. This was attributed to the inappropriate response by flight crew to the transient loss off airspeed indications in the cruise caused by high altitude ice crystals blocking the Pitot probes.
20th April 2012 - Airbus A321-231 Registration G-EUXM encountered atmospheric conditions on two occasions which resulted in temporary loss of reliable air speed data. A PAN Was declared and the aircraft diverted to Stansted for an uneventful landing. While during the events it was not known what was causing the erroneous data due to additional problems being presented to flight crew and the distraction of a bright flash due to electrical discharge phenomena. Pitot icing, it was concluded, was the likely cause of the problems.
21st November 2013 - Etihad A330-200 Flight EY473 Brisbane to Singapore. The pilot in command rejected take off due to airspeed discrepancy. After some troubleshooting back at the gate, another take off was attempted. A discrepancy was once again noted after V1 decision speed, the aircraft rotated and shortly after issued a Mayday. The aircraft returned to Brisbane for an overweight landing. The captains Pitot probe was later found to have been totally blocked by mud dawber wasp activity occuring in just a two hour turn around period.
12th February 2018 - Antonov AN-148-100B operated by Saratov Airlines had departed Moscow's Domodedovo airport en-route to Orsk when it crashed. It is reported, but yet to be confirmed, the Pitot heat had not been switched on as part of the take off check list. The Pitot probes were likely to have been iced up with a loss of reliable air speed information.
(The following three incidents all took place on the same morning and are thought to be all attributed to heavy icing and pitot blockage)
26th February 2018 - Airbus A321-200 Registration HA-LXD Unreliable air speed indication while climbing out of Sofia, PAN Declared. Returned to Sofia.
26th February 2018 - Airbus A321-200 Registration HA-LXL Rejected take off from Sofia at 80 knots due to unreliable air speed indication. The aircraft slowed safely and returned to the apron.
26th February 2018 - Airbus A321-200 Registration HA-LXP While climbing out of sofia the crew requested stop climb at 10,000 feet MSL, Climbed on to 12,000 due terrain, subsequently declared PAN,PAN,PAN reporting unreliable airspeed. Diverted to Budapest for a safe landing.
20th July 2018 - Malaysia Flight MH134 Airbus A330-300 was released with all three Pitot covers left in place. After take off, the aircraft safely returned to Brisbane having issued a Pan Pan Pan.