Recently, there was an incident where a Delta Airlines charter flight carrying the Oklahoma City Thunder basketball team was struck by an "unidentified object". Delta's official statement claims that

Delta flight 8935, operating from Minneapolis to Chicago-Midway as a charter flight for the Oklahoma City Thunder, likely encountered a bird while on descent into Chicago. The aircraft, a Boeing 757-200, landed safely without incident; customers have since deplaned and maintenance teams are evaluating.

While I do not agree with the UFO label that this story seems to have run with, I am shocked that a bird (especially at such an altitude) could cause such severe damage to the nose cone (even at such speeds).

Is this characteristic of a bird strike and how severe would this incident have been had the collision been with the windshield?

  • $\begingroup$ This is PPRuNe's take on it pprune.org/rumours-news/… $\endgroup$ – CSM Oct 29 '17 at 14:58
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    $\begingroup$ "I do not agree with the UFO label that this story seems to have run with" Why not? The plane was clearly hit by an object. That object was at 30,000ft, so it seems reasonable to describe it as flying. And they don't know what the object is, so it is unidentified. "UFO" means what it says. It does not mean "alien spacecraft". $\endgroup$ – David Richerby Oct 30 '17 at 15:39
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    $\begingroup$ Hi @DavidRicherby, (for better or worse) it's a simple, undeniable, fact that (in English and many languages) "ufo" has come to mean "alien spacecraft". I am the #1 hater of words changing meaning (I spend half my life trying to explain to people how to actually use "apocryphal") - but you are, simply, in the only possible meaning of word meanings, "wrong" to asset that "ufo" does not mean "alien spacecraft". $\endgroup$ – Fattie Oct 30 '17 at 17:33
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    $\begingroup$ @Fattie Fair point. I should have written "[UFO] doesn't only mean 'alien spacecraft'." $\endgroup$ – David Richerby Oct 30 '17 at 17:39
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    $\begingroup$ To put it another way, if we knew it was an alien space craft, it wouldn't be unidentified. $\endgroup$ – Shufflepants Oct 30 '17 at 21:31

Bird strike happens all the time - almost on a daily basis. See avherald : there are 9 instances of bird strike on the past 7 days at the time this answer is written. Usually it is ingested into the engine (which usually turns out to be a non-issue), other times it impacts the cone or leading edge of the wings or knocks off a pitot tube.

While a few incident make it to mainstream news from time to time, bird strike is a common occurrence in the aviation industry. It is an unusual situation, but not a dangerous situation if the pilots handle it properly.

How severe if it collided with the windshield? The windshield is tested against this type of impact during certification. At worst the outer layers will crack, and the pilot will execute the landing using the "cracked windshield" procedure (Yes there is a procedure written for this scenario).

A note about the UFO: technically it is an UFO, an Unidentified Flying Object. It could be a bird, a drone, weather balloon etc. Examination of the impact area might reveal what the object was.

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    $\begingroup$ +1 I didn't know how to handle the UFO part in my answer =) $\endgroup$ – Bageletas Oct 29 '17 at 5:32
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    $\begingroup$ Is the term "UFO" still used as its origin meaning in technical documents? $\endgroup$ – Ooker Oct 29 '17 at 22:33
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    $\begingroup$ UFO != Alien aircraft. Unless it is an uindentified flying object owned by someone from outside the USA, then it is indeed an alien aircraft. But not of the extraterrestrial sort. But just because we don't manufacture aircraft outside the ionosphere yet. $\endgroup$ – Mindwin Oct 30 '17 at 16:09
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    $\begingroup$ @Mindwin so if I went to the moon and folded a paper airplane there I would have a extraterrestrial aircraft. $\endgroup$ – ratchet freak Oct 31 '17 at 12:24
  • $\begingroup$ @ratchetfreak indeed. But not of the xenobiological kind of extraterrestrial UFO. $\endgroup$ – Mindwin Oct 31 '17 at 12:36

If you observe the photos of the incident, you will find that the dent was in the radar dome in the nose, which is not nearly as strong as the windshield. Doesn't need to be, it isn't part of the pressurized section. Note also that the dome was not punctured, so whatever hit it was fairly blunt, like a large bird. The absence of blood on the dome is a bit curious, though... maybe the photo just doesn't show it.

Note also that the radar dome didn't fracture apart, it just buckled but remained intact and remained in position. It did what it was designed to do - take an unexpected hit and not shatter or dislodge and possibly FOD the engines.

Modern airliners have been tested extensively for bird strikes, especially on the windshield, as a breakage or intrusion at speed there could be catastrophic to the aircraft, as in rendering the pilots blind or unconscious.

This isn't a very serious incident. The radar dome was buckled, but that's about all that happened. Radar domes on airliners have suffered similar damage in flight from large hailstones, without seriously impacting the aircraft's ability to fly.

As it is, the flight crew responded exactly as they should have, and the flight landed without further problems. Had the bird hit the angled and much stronger windshield, and not the blunt, forward facing radar dome, it would most likely have just glanced off, maybe leaving a nasty blood smear.

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    $\begingroup$ Some of the pictures I saw seemed to indicate the aircraft was wet. Some rain before landing could explain the lack of blood or other physical signs. (One of the avherald commenters pointed this out.) $\endgroup$ – Zach Lipton Oct 29 '17 at 9:01
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    $\begingroup$ Animal impacts don't have to be bloody. I remember one time when a rabbit decided to jump out in front of my car as I was doing 60+ MPH down the Interstate. I had no time to react, and I felt the impact against the car's frame. When I reached my destination, I looked at the front of the car and saw no damage and no blood anywhere. $\endgroup$ – Mason Wheeler Oct 29 '17 at 18:38
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    $\begingroup$ I once flew with a 727 pilot who told us about striking a goose that penetrated the radome and the bulkhead. The copilot had blood and guts on his legs when they landed. $\endgroup$ – TomMcW Oct 29 '17 at 18:45

There are a couple of assumptions that need to be cleared up.

While I do not agree with the UFO

But the official word was not UFOs... It was labelled a likely bird strike.

especially at such an altitude

This question address the fact that birds can fly very high and there was a confirmed bird strike upwards of 37500 ft.

could cause such severe damage to the nose cone (even at such speeds).

You're really underestimating the forces here. The bird metioned in the last question could have weighed upwards of 20 lbs. That's 20 lbs, mach 0.8, hitting a thin composite radome.

Is this characteristic of a bird strike

YES. Here is an AV Herald search result for bird strikes. They happen all the time. If you randomly click through the search results you will see either pictures or descriptions of bent radomes, broken props and struts, or engine flamouts.

The beauty of it all is these planes all landed relatively safe (even the miracle on the hudson!)

how severe would this incident have been had the collision been with the windshield?

It depends. If the pilots are both still conscious and can see they can fly the plane. In theory they could even "fly blind" like they were flying IFR (landing would be tricky depending on the runway equipment).

Heck a pilot got half sucked out of a plane due to a faulty window and even he lived

Planes are like cars. They balance functionality with sturdiness. The vehicle has done its job if you can walk away from an accident.


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