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In the case of Aeroperu Flight 603, a fatal crash was caused by duct tape that was accidentally left over some or all of the static ports on the underside of the fuselage after the aircraft was cleaned. As the static ports are critical to the operation of virtually all of those flight instruments that provide aerodynamic data regarding airspeed, altitude and vertical speed to the pilots and to the aircraft's computers, this bit of duct-tape caused the total failure of multiple basic flight instruments.

Another crash was caused for a similar reason: pitot tubes that were blocked by an insect led to flight instrument failure, and later, a tragic crash. This was Birgenair Flight 301.

These accidents happened in the mid-1990s. Today, two decades on, are there better systems in place to ensure that static ports or pitot tubes don't get blocked, causing instrument failure?

Edit 1: In both these flights, the pre takeoff checks missed out on the blocked static ports/pitot tubes. Human error clearly happened at this stage. Question is, have an steps been taken to make the flight instruments proof to this particular human error?

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    $\begingroup$ I'm not a pilot, but shouldn't a pre-flight inspection of the plane show random bits of duct tape sticking to the fuselage where they shouldn't be? If that's the case, no amount of technology will fix stupid pilots. $\endgroup$
    – FreeMan
    Oct 18, 2015 at 17:54
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    $\begingroup$ @Freeman Although the tape should have been detected during pre-flight checks the static ports are several feet in the air and the flight took place in the middle of the night. I'm not sure how the aircraft was painted but if the part where the static ports are is grey the duct tape would be tough to see. $\endgroup$
    – TomMcW
    Oct 18, 2015 at 21:09
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    $\begingroup$ @TomMcW Thus the requirement (now) that the tape used for covering the static ports is bright & contrasts with the surrounding paint so it is easy to see. And at night, any walkaround should be performed with a flashlight, so that the pilot can see them (as well as plenty of other things). $\endgroup$
    – Ralph J ♦
    Oct 18, 2015 at 21:20
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    $\begingroup$ @Ralph j I used to watch the pilots doing their walk-around with flashlights and wonder how they could possibly be certain they didn't miss anything. Seems like they'd only catch stuff if it was pretty obvious. Something like the wasp nest in the Birgenair crash would require going up on a lift to see it. $\endgroup$
    – TomMcW
    Oct 18, 2015 at 21:30

2 Answers 2

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The best thing way to mitigate an issue like this is to draw attention to during the preflight check. Its becoming common to use covers that have a nice big red "Remove Before Flight" tag on them. These should be used as much as is practically possible (storage, cleaning, maintenance etc.)

Something like this would do nicely. enter image description here (source)

Similarly the aircrafts paint may be done in such a way to make the port stand out.

enter image description here (source)

Caps/Covers for both static ports and Pitot Tubes are generally a good idea and can help prevent a clog that occurs while the plane is on the ground. As with anything diligence during preflight is key to avoiding this issue.

Most larger aircraft pilots call out "airspeed alive" during their takeoff roll as a way of confirming the Pitot system is working. If the air speed indicator does not read, the general procedure is to abort the takeoff.

Some aircraft may also be equipped with a radar altimeter which can help mitigate serious issues by providing an altitude system not based on the static system. However this only works at lower altitudes.

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A clogged static port is a little bit more difficult to recognize on takeoff than a pitot port being cligged.

If the pitot was clogged, during takeoff there would be either no indication of airspeed or an extremely low value. The pilot monitoring should recognize this during takeoff and call for an abort.

If all the static ports are clogged, the pilots would only recognize it after takeoff. Without accurate altitude info, it would be difficult to land safely in IMC conditions. The transponder altitude and altitude input to a non-WAAS GPS would inaccurate.

In all the airplanes I fly, each Air Data Computer has a static port on each side of the airframe to preclude a simple piece of tape of causing disaster. Not only that, there is usually another static port that is just for the standby instruments, airspeed and altimeter. Making something that happened before less likely.

As @Freeman states, a thorough preflight should catch those issues.

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    $\begingroup$ Unfortunately with the static port issue if there is tape over one port there's probably tape over all of them. Redundancy would be negated. Is there no way to test that the instruments are getting good data before take off? $\endgroup$
    – TomMcW
    Oct 18, 2015 at 21:33
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    $\begingroup$ Not necessarily. The mechanic or washer could have started getting the tape off, got distracted and didn't get the tape from the other ports. $\endgroup$
    – wbeard52
    Oct 18, 2015 at 22:16
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    $\begingroup$ Certainly true. What I'm saying is that redundancy is a great way of accounting for most types of failures and, like you say, that makes the problem much less likely. But there are situations, like on the Aeroperu accident, where all the ports can be blocked. That being the only accident I know of where happened indicates that it is almost always caught in preflight but you say if they are all blocked there'd be no way to know until you were airborne, at which point you'd be in a real pickle without visual refs. Seems like that particular accident is still a possibility unless there's some oth $\endgroup$
    – TomMcW
    Oct 18, 2015 at 22:32
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    $\begingroup$ ... cont way of verifying the static data. $\endgroup$
    – TomMcW
    Oct 18, 2015 at 22:34
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    $\begingroup$ Known pitch & power settings, GPS groundspeed, radio altitude, ILS glidepath... It can't be fun, but you don't lose EVERYTHING with complete pitot-static failure. $\endgroup$
    – Ralph J ♦
    Oct 19, 2015 at 0:19

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