Too cold to fly??

The fatal crash of a Saratov Airlines Antonov An-148 in Russia may have been tied to the frigid weather in Moscow. Initial analysis suggests that the aircraft’s pitot-static pressure sensors – devices that measure air speed and altitude – were not heated on the fateful flight. That failure led to inconsistent data between the redundant reporting systems on the flight deck. The pilots attempted to fly the aircraft manually rather than on autopilot during this time and ultimately were unsuccessful in keeping the plane aloft.

A (pretty cheesy) graphic explaining the pitot system
A (pretty cheesy) graphic explaining the pitot system

That’s scary in many ways. More concerning, perhaps, are reports that earlier in the month some Sukhoi SuperJet 100 aircraft had similar speed disagreement issues.

A series of seven incidents occurred on February 4-5, 2018, amidst heavy snowfall and frigid (-12 C/10 F) temperatures in Moscow. In each instance the aircraft either aborted its takeoff roll or returned to the origin airport.

One apparent example, Aeroflot flight SU2344 on 4 February, shows evidence of fluctuating actual air speeds as the pilots attempted to resolve the issues.

Flight data from an Aeroflot SSJ that had to return to its departure airport, showing the speed readings variation, among other things.
Flight data from an Aeroflot SSJ that had to return to its departure airport, showing the speed readings variation, among other things. (image via FlightAware)

Russian aviation regulator Rosaviatsia’s initial investigation detected ice in front of the pitot tube inlet, affecting the function of those tubes. For its part Sukhoi insists that the heating system is automatic and that it is impossible for extended issues to occur with those sensors.

Still, it is hard not to see a little irony around a Russian airliner succumbing to cold weather issues.

Header image via Flickr/CC BY-SA

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Seth Miller

I'm Seth, also known as the Wandering Aramean. I was bit by the travel bug 30 years ago and there's no sign of a cure. I fly ~200,000 miles annually; these are my stories. You can connect with me on Twitter, Facebook, and LinkedIn.


  1. Too cold to not manually turn on the pitot tube heaters on the Antonov if the initial reporting is correct. Interesting pilots online say the 727 and 737 classic also had manual heating switches but on more modern jets now they go on when engines are on.

    1. Yeah….with the Antonov that mistake cost a lot of lives. Very unfortunate. And I agree that it is mildly surprising that functionality was manually controlled rather than simply part of the system. Though the SSJ incidents raise questions about the automated option, too.

    2. Seth Miller Indeed. And not just a cold climate issue…it would just appear at lower altitudes in cold weather as at cruise, obviously even more freezing.

  2. So is it primarily just an issue with Russian built jets then?

    During both of my trips there this winter it was warmer than Minnesota (granted, not a very high bar).

    1. In this case the Russian built jets in Moscow are the ones with issues reported. Sukhoi claims other types were similarly affected but I haven’t seen any regulatory reports on that front. I also haven’t looked too hard.

  3. As I recall, there was an Air France flight from Rio to Paris that crashed in the Atlantic due (probably) to ice in the pitot tubes. Is there any other way to determine an aircraft’s airspeed?

  4. Pilots are trained for this, especially American military pilots. With a set pitch and power setting climbing/descending/level flight you can garentee the aircraft will roughly maintain safe speed for flight until checklist can be run to solve the problem and safely land. Safe speed you ask? Somewhere between clean maneuver and max placard which in most cases with jet/turbojet planes is a window of 150knots.

  5. Seth, pitot issues and associated speed discrepancies are not a reason planes should crash, and there have been several “warm climate” examples of this. Appears to be poor airmanship, no?

    1. I think it is a bit of both. It has to be.

      Pilots need data to make sure they’re operating within the right ranges of speed, altitude, attitude, etc. Some of that should also be possible without the indicators at a basic level but expecting pilots to run their systems that way regularly is also a bad way to play IMO.

      It is definitely very cold at altitude so it cannot only be the cold weather causing the issues. At the same time, however, the melt/freeze cycle can certainly contribute to the issues. Ice in a pitot tube has proven fatal several times now.

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