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This Boeing 737 was hit by a bird and continued all the way to its final destination, from Prague to Las Palmas.

What actually happened here? Was the incident considered a bird strike or an engine stall? Can an aircraft continue to its final destination after a bird strike?

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  • $\begingroup$ Do you have any reference other than the link in the question? Questions should be self-contained. $\endgroup$ – Toby Speight Apr 4 '18 at 17:21
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Since it hit a bird, it was a bird strike. Nothing else matters for that classification.

The puff of flame suggests there probably was a momentary compressor stall. That is the compressor was unable to maintain the pressure as the flow was disrupted by the bird, the flow through the engine slowed down for short while, some extra fuel accumulated in the engine and as the flow restored, the extra fuel burned past the jet, creating that puff of flame.

The engine did not flame out, that is, it continued to run. Older engines tended to get into a repeated cycle of stalls once they stalled as the accumulated fuel from one stall would cause the pressure to increase beyond capability of the compressor and cause another stall, but modern engine computers will automatically restrict the fuel flow to prevent that.

The aircraft continued, because the engine was running and all parameters (RPM, temperature, vibrations, pressure ratio, oil pressure) were indicating normal values.

If the engine stopped, or if some indications were out of tolerance, they would have to return, since two-engined aircraft are required to land as soon as possible when one engine fails. But it clearly did not and they continued (and may not have been aware of the bird strike at all until inspection after landing, because the stall handling is automatic and if no values were out of tolerance, they would not get any warnings).

The engines are designed and tested to continue running after ingesting a small bird [1], so this was actually the expected outcome. The test usually involves launching dead chicken into the running engine (on the static test bench) from a chicken gun [2]. Said gun is also used for testing canopies and windscreens. Frozen chicken are occasionally used too; contrary to the urban legend not due to stupidity, but intentionally as tougher version of the test [3].

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Federico Apr 4 '18 at 16:13
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    $\begingroup$ That test is also very effective at ensuring not only that the engine continues to run, but that the chicken is thoroughly dead. There is not a single documented case of a live chicken sneaking through quality control and walking away from the encounter. $\endgroup$ – Cort Ammon Apr 4 '18 at 21:19
  • $\begingroup$ I find it somewhat hard to believe that the pilots could be unaware "of the bird strike at all until inspection after landing"; unless flames shooting out of a jet engine is a normal occurrence in air travel, wouldn't at least some of the passengers have noticed, been very concerned, and notified the cabin crew, who then would (presumably) have let the pilots know at some point that "hey, just so you know, the number one engine was spewing flames just after we took off"? $\endgroup$ – Sean Apr 4 '18 at 21:59
  • $\begingroup$ @Sean - A puff of flame (lasting approximately 1/5th of a second) is hardly "spewing". Probably they just blinked and missed it $\endgroup$ – Richard Apr 5 '18 at 7:57

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