Ryanair "birdstrike" out of Corfu, 24th September

[davidginola]

Evening all. I had the pleasure of flying back from Corfu last Thursday (24th September) with Ryanair to Prestwick.
After a 4 hour weather delay, we finally departed to a very loud thud which seemed to come from the right side of the aircraft. There was then a noticeable noisy vibration sound during the climbout, after which it seemed like we levelled off and engine power was significantly reduced.

After about 15 minutes, the captain came on and told us that unfortunately they suspected that they'd "hit a flock of birds" on departure, and would therefore be diverting to Brindisi where the Ryanair engineers would check out everything "just to be on the safe side."

Another 15 minutes passed, and the captain came back and said that following a discussion on the flight deck, along with the engineers, and also with Corfu ATC (who'd failed to find any evidence of a bird strike) the decision had been taken to continue to Prestwick. This was met in the cabin with an equal mix of relief (at getting to go home) and worry (at potentially continuing despite 15 minutes previously being told that a diversion was necessary.)

My questions are:

1. Other than a birdstrike, is there anything else which would explain the loud thud and then vibration on departure?
2. Is it normal to take a decision that not only a birdstrike has occurred, but to divert the aircraft, only to change your mind?
3. What are the chances that the crew involved would be able to explain what actually happened?!

I'm an operational controller, so I know how common birdstrikes are and the conversations which take place after they're suspected to have happened. However, in my experience, diversions seem pretty rare, and I struggle to see what new evidence could come to light which would change the decision to divert once that decision has been made.

Thanks a lot!

[golfyankeesierra]

From an operational point of view, I can certainly understand that the initial decision is not to return to Kerkira as it's a short runway but to go to Brindisi instead.
But then when something is found with the engine (which I think is probable) the aircraft will be stuck there.
So when it's running fine the instruments show normal and there is no apparent damage, I would prefer to continue to destination (only when it is home base of course).

Based on your description I would have done the same thing as the RYR crew.

[F-16GUY]

I don’t quite agree in the above decision to continue. In 2013 we had a bird strike on one of our F-16’s in Estonia while on a Baltic Air Policing mission 40 nautical miles south of Tallinn. One of the birds struck went into the engine. The pilot noticed a “thud” and had a minor grinding noise and minor vibrations for 30 seconds. After that the noise and vibrations disappeared. The engine instruments and the engine response were normal during the entire event. Pilot decided to land at nearest suitable airfield which in this case was Tallinn. Landing was performed a short while after and was uneventful.
Technicians and engine specialists that where sent to check the plane before it was returned home discovered massive structural damage to the intake and engine. Engine specialist estimated the engine would have continued to run for a maximum of 15 minutes more before tearing itself apart.
From the cockpit it can be very difficult to assess the damage a large bird can do to an engine or airframe. Obviously if the engine stops instantly, shows abnormal indications or there is a breach in the pressure hull, it will be obvious that that the crew needs to land. But even events that do not seem to have done any damage might develop into an engine failure. Therefore, I would elect to land at the nearest suitable field if I have a reasonable suspicion that the engine was hit by a bird. But then again, my company does not have to make money for the stake holders, and the aircraft we operate are only single engine.

[RAT 5]

Another 15 minutes passed, and the captain came back and said that following a discussion on the flight deck, along with the engineers, and also with Corfu ATC (who'd failed to find any evidence of a bird strike) the decision had been taken to continue to Prestwick.

But then again, my company does not have to make money for the stake holders, and the aircraft we operate are only single engine.

About the 1st comment. Sounds fair enough. Pilots tend to go by what the instruments tell them and by what the a/c 'feels' like. No evidence to suggest anything is amiss = continue.
The 2nd comment explains why this was not the case with an F16.

I wonder if they found anything in PIK? One day out of GLA, en route PMI, a flock of seagulls flew down the left hand side doing about 190kts. Astonishing, feathers and wings going every which way to hang on. You could see the whites of their eyes and they were not happy. We waited for the 'thrump, bang, shudder' but it never came. All looked OK from the inside. We continued. On walk round in PMI there was a large hole precisely on the leading edge of the horizontal tail-plane and it was full of seagull. They would not have found any evidence of bird-strike either. Firstly it was well outside the airfield, and we had all the debris aboard. I was amazed that there was no further damage caused by 3.00hrs at M.072. Sturdy a/c B732. Shoot em full of holes and they'll get you home; biggles.

[Skyjob]

Other than a birdstrike, is there anything else which would explain the loud thud and then vibration on departure?
Is it normal to take a decision that not only a birdstrike has occurred, but to divert the aircraft, only to change your mind?
What are the chances that the crew involved would be able to explain what actually happened?!


1. There could indeed be other reasons, but let's leave details of those untouched in this discussion, as you are asking an operational question rather then a technical detailed one;
2. Let's be clear, a suspected bird strike occurred, which may (or not) have happened inside the airport perimeter, thus ATC can possibly only comment on the speculation in case it may have been within.
3. Little chance...

However in general, for the non flight crew reading this forum including OP:

Initial crew actions would involve evidence gathering, which would include a more closer look at existing engine parameters, possible asking cabin crew if any smells were observed during or immediately after the event, ensuring all extended flaps and slats have retracted to en-route configuration without problem, etc.

If no smells were observed then there is a reasonably good chance that any suspected birds may have missed the engine core, thus not damaging the internal of the propulsion systems.

If no vibrations above and beyond those expected during flight are recorded by the engine instruments AND there is no significant increase in vibrations during further climb it would indicate nil or little fan blade damage has occurred if it has been struck. The front fan [indicated at %N1 on the engine instrument panel for pilots to see] on the engine will rotate faster in thinner air aloft, thus if there would be any damage to one or a few of its fan blades, vibration would soon become very high when the engine is used at full climb power, requiring the crew to reduce engine power to remain within limits, this would likely result in a diversion subsequently.

If all extended devices (slats and flaps) have been fully retracted then there is no indication of damage to the extension/retraction mechanism, thus the aircraft is configured for en-route flight.

Operational discussion points then would include (but are not limited to) if it would be more sensible to land with a relatively high (possibly over maximum landing) weight at a destination offering a suitable runway which has subsequent required engineering cover, or to continue to a different suitably equipped airfield further afield, or to continue to intended destination if all parameters are within limits.

Contacting Engineering and/or Operations can assist in such decision making, as they can assist in diagnosis and advise of engineering cover [Engineering] and may have additional information which may not be pertinent to the aircrew [Operations], including advice on relevant NOTAMs, available handling agents and/or strikes, information of which may not be required to be carried by crew for such suitable diversion airports as part of the preflight briefing package (contrary to some passenger belief, aircrew do not carry all NOTAMs for all airfield in Europe thus may not be aware of any imposed unless questioning this).

An initial decision of aircrew to divert after such event may have been fuelled by simulator training and expectation. However having consulted with engineers they may well have reassessed such decision and review such requirement.

In the process of decision making crews are there to ensure a safe flight, using all available resources to come to a decision and define a course of action. This decision making model is a fluid and continuous process which will be reviewed at each finding of evidence or additional piece of information.

Ultimately, airlines and its crews are ensuring to achieve "happy" passengers having arrived at their destination safely.

[de facto]

Only fools never change their mind.

[mockingjay]

EU261 will likely see a reduction in safety related diversions. More flights will continue to destination as bird strikes are not an extraordinary circumstance so the airline is liable for tens of thousands of pounds of compensation. Very sad state of affairs when once safety regulators now ensure anything but safety (look no further than new EASA FTLs coming soon to a sky near you).