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I took a look at the post 'What things can a passenger look out for, to indicate an emergency?', and remembered this video I've seen.

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Obviously, video uploader claims that this take off was unsafe due to some ice and snow on the wings. Was he right? Were the pilots really breaking any regulations?

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    $\begingroup$ It's important to remember that whether a given condition is safe or not is really not a binary choice. Think of "safe" being a probability index along a line starting with zero on the left being "this airplane is certainly not going to be able to fly" and 1.0 on the right being "this airplane is certainly going to fly. While that index can be zero, it will never be 1.0 but can only approach 1.0. And remember that in third world countries, operators are often willing to fly with a lower such index than might be used in so-called first world countries. $\endgroup$
    – Terry
    Feb 5, 2017 at 2:06

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It appears that there was a considerable amount of contamination, either snow, ice, frost, or a mix thereof, on the wing when the takeoff roll started, and that is not considered safe under any current standards I'm aware of.

There are markings on the top of the wing for the 737 Next Generation series that define an area where cold-soaked fuel frost is acceptable up to a defined thickness, but the area covered by the contamination in the video extended beyond those markings, so even if it was CSFF (which I doubt, given what's shown late in the video), it was still more than what's allowed.

Late in the video with the aircraft flying, we see that much of the ice is no longer present, which means that it detached from the wing at some point. If it was dry snow that blew off in the first 10 or 20 knots of the takeoff roll, that's no big deal, but you don't see the ice gone until late in the video -- this isn't simply dry snow. Plus, you still see significant patches of ice adhering to the wing at the end of the video -- which suggests that it isn't CSFF nor dry snow, but ice.

The current accepted standards of safety in commercial aviation don't permit taking off with any ice adhering to the wing, and from what is shown in the video, it certainly looks like that's what was done here. (Disclaimer, I'm no expert on watching u-tube videos of ice-covered wings, so there may be more going on here than is apparent on first or second viewing.) IF that's correct, then I'd have to agree with the title of the video, that this was unsafe.

The standards of safety allow for a lot of margin, so that when mistakes get made they are still likely to be survivable, and it looks like that's how things turned out here. Things were done wrong but everybody made it out okay. But... what if one more thing had gone wrong? What if they'd lost an engine at rotation? Would the aircraft have been able to climb out with one engine & the wings in this condition? Or would these guys have been headline news of a crash out of Sarajevo that killed all on board plus how many more on the ground?

No, this looks pretty far out of bounds to me.

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The video appears to show frost or ice on the wing of an airliner during takeoff. Normally this is discouraged because even a thin coating of ice can disrupt an airfoil's boundary layer airflow, causing a premature aerodynamic stall and dramatically increased functional drag.

However, extenuating circumstances often intrude upon standard safety margins. There are many reasons why a flight crew might risk flying with an apparently contaminated wing surface:

  • The flight crew had hand inspected the wing and found it smooth even if discolored.

  • No de-icing was available.

  • De-icing was available but the takeoff waiting line was so long that the wing iced up again while taxiing. This was the minimum amount of ice that the flight crew could get the plane to the takeoff point with.

  • The captain is a right bastid and ignored the tearful pleas and terrorized screams from his first officer.

  • The discoloration on the wing is not ice or frost, but de-icing fluid.

  • Anything is safer than hanging about on the ground at Sarajevo Airport.

In any event, you are survived to tell the tale, so by definition the flight crew's judgement was correct.

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    $\begingroup$ Unless mortars were falling at the airport, none of those extenuating circumstances justify what that crew did. If no deicing is available, or the line is long, or ice keeps reforming, you don't go. Landings are mandatory, but takeoffs are optional, and if you can't take off safely, don't take off. Simple as that. Smooth ice is still ice, not safe. Deicing fluid is either clear (Type 1) or green (Type 4) so that it does NOT look like ice -- and it would shear off during the takeoff. And surviving a stupid decision, doesn't make the decision less stupid. They dodged a bullet. $\endgroup$
    – Ralph J ♦
    Feb 5, 2017 at 0:39
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    $\begingroup$ "100% of passengers didn't die" is a pretty minimal standard for evaluating a crew's judgement. I think there's a lot we can't tell just by watching the video, but surely it is possible for a crew to exercise poor judgement without killing everyone on board. It's supposed to be about margins of safety and good decision-making, not "everyone didn't die so it's all ok." $\endgroup$
    – Zach Lipton
    Feb 5, 2017 at 1:31
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    $\begingroup$ Though others obviously disagree, I upvoted the answer. I found it realistic (though a bit colorful) at least insofar as the conditions I encountered in the 30 years of flying I did, and especially the last 12 years going into third-world countries. I retired in 1999. Perhaps things have changed. I hope they have. I think it important that Mr. Breveleri is not advocating operating with reduced safety margins, but recognizing real world conditions that perhaps influenced the captain's decision. $\endgroup$
    – Terry
    Feb 5, 2017 at 7:41
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    $\begingroup$ No, it's not. A pilot aspiring to "I didn't kill anyone today" is not a professional. $\endgroup$
    – acpilot
    Feb 5, 2017 at 15:46
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    $\begingroup$ While I agree that not killing anyone is important, it is also beneficial if the airplane comes down in as few pieces as possible. There is more to good piloting than not killing passengers. I personally always want to have an option B when I fly. $\endgroup$
    – Peter Kämpf
    Feb 5, 2017 at 16:47

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