Flock of birds near runway

[Cybersquatter]

As we were queuing for the runway in Istanbul this morning, I noticed that there was a flock of starlings (or something like starlings) regularly flying around in a big formation around the start of the runway. Every so often they would settle down for a couple of minutes, then they'd be up again, getting very close to aircraft that were sitting on the runway waiting to take off.

Isn't there a huge risk that they'd be sucked into the engines? I was kind of surprised that a van didn't come along to scare them away.

[Cybersquatter]

No aviation experts with any inputs on this?

[eastern wiseguy]

Where I am we have a policy of constant harassment. The airport employs Bird scaring vehicles with lights ,distress calls,and flare guns. They also use shotguns. As a controller I will hold departures until I can get a vehicle to clear the area,. Bird strikes can have serious consequences. Think the US Airbus which landed in the Hudson river and this one ,which whilst extremely nasty ended well.
You will see that the Thomson hit only ONE bird.

Boeing 757-200 from Thomsonfly at Ringway/Manchester Intl Airport by Simon Lowe - YouTube

[Di_Vosh]

Cybersquatter

Birds are potentially a major safety issue for reasons both you and eastern wiseguy alluded.

The problem is, is that the threat is common. Most pilots have had so many near-misses with birds that the threat of birdstrikes is perceptually lower. I've only got around 4000 hours flying. During that time I've hit two birds; both on landing. I couldn't count the number of near-misses that I've had. (Have you ever stood on the cerb of an arterial road? Less than 1 metre from cars and trucks moving at 80-100km/h? Very risky, but you've done it so often and without incident you don't see the risk of a driver having a "bad moment").

IMHO, most pilots won't really care unless they see the birds in front of them when they're lined up on the runway. In the scenario you described, unless that flock of birds was directly in front of the aircraft when the aircraft was lined-up on the runway, the pilots wouldn't have cared.

Birds do get sucked into aircraft engine intakes, but that doesn't mean that it will automatically create an engine failure/fire. In a modern jet engine, only a small percentage of the face of the fan goes into the combustion chamber. A small bird such as a sparrow or starling may go through the main fan with little to no damage.

It should be noted that the Hudson river aircraft went through a FLOCK of geese (Geese are 20+ kg birds) and I'm pretty certain that the bird that got sucked into the 757 on the video was a "large" bird.

Many airports use bird scarers of various descriptions (places where I fly are either a bloke in a car or with a shotgun loaded with blanks). Sadly, birds love airports.

[Lucerne]

Where aerial agriculture is concerned, bird strikes are a common (almost daily) occurrence. These include ingestion into Garret Turbine powered machines which rarely result in any power loss, much less, engine failures.

There are no statistics on the frequency of such events as they are so common-place. I dare say that there is also a high frequency of unnoticed/unreported bird strikes and ingestions which will never contribute to the documented history of such. In other words, I'm sure it happens every day to airliners as well.

[DaveReidUK]

Where aerial agriculture is concerned, bird strikes are a common (almost daily) occurrence. These include ingestion into Garret Turbine powered machines which rarely result in any power loss, much less, engine failures.

Unless there is a new generation of turbofan-powered agricultural aircraft that I'm not aware of, I assume you're talking about the TPE331 turboprop that powers many ag aircraft such as the Thrush. Ditto the PT6 on the turbine Air Tractors, etc.

In that case, I'd suggest that once a bird has been through the propeller, the chances of these being any sizeable bits left to be ingested by the engine itself are low.

[ExXB]

It's not just birds that are a problem. Pity poor Fort Nelson (http://www.vancouversun.com/technology/Busy+Fort+Nelson+airport+seeks+funding+keep+moose+other+anim als/7534164/story.html).

[Lucerne]

DaveReid - the problem really only exists with the Garrett engines as they are unfiltered.

It is surprising how few birds actually contact the blades of a propeller as they pass through its arc. This is the result of the function of the aircraft's speed as opposed to the speed of the propeller blades and the gap in between them.

Most Garrett powered ag planes do have a very course grill installed in front of the air intake which will break foreign objects down into pieces of a couple of inches in width. This considered, it is still a testament to the engine's particle separation ability that a bird ingestion can be of little consequence to its sustained operation.

Garretts do, however, suffer from internal corrosion due to their constant ingestion of corrosive pesticides and fertilisers being applied during ag operations. It is for this reason, I believe, that the PT6 and Walter turbines are far better suited to agricultural and fire operations.

[Agaricus bisporus]

Well, they could shoot the moose and cook them on the grill(sic) on Lucerne's Garrett. Tasty snacks for waiting passengers!

[ExXB]

I'll let you shoot the moose! Those guys are huge. I've seen the results of a collision between a moose and a Ford F150. The moose won, but it was dead too.

[Capot]

It is surprising how few birds actually contact the blades of a propeller as they pass through its arc.

It's Saturday, raining, let's see the numbers...

Say 250 KPH airspeed, 3-blade prop, 2000 RPM. Just for fun, not necessarily typical of anything.

250,000m per hour comes out at 69.4m per second, if Windows calculator is right. So the spinning prop moves forward that far through the air in one second, at that speed.

2000 RPM is 33.33 RPM per second.

So the propeller rotates 33.33 times in every 70m forward movement.

That would be 2.1 m forward movement for every propeller rotation.

So, between each blade's passage of a point on the disc, the forward movement is 0.7m. Or 1.4 m at 1000 RPM, interpolate or extrapolate as you will with speed/RPM variations; it's a straight line.

Hmmm, got to be a fairly agile bird to get through that, but possible, I would think; is my arithmetic flawed? I was never very good at it.

[Pax Vobiscum]

I agree your arithmetic, Capot. I guess what it means is that a larger bird, say a Canada Goose, would have little chance of coming through unscathed, but a Starling might well be OK.

[Lucerne]

I can concur from experience that the starlings and similar sized birds make it through more often than not. You would be right in assuming that the Canada Goose has les chance although I have seen a situation where a Brolga made it through the prop of an AT-502 and successfully demolished the windscreen. It came to rest on the cockpit floor below the spray lever after the pilot sustained significant neck and chest injuries. The bird was still in one piece although dead (of course).

The starlings still regularly make it between the blades of a -11 Garret running a 5 bladed prop and spraying at an average speed of 120kts, Propeller Speed - 2100rpm. At night the only indication of an ingestion is a series of sparks shooting from the exhaust. Daylight ingestion is commonly unnoticed in flight but evident from the remnant debris on the intake grill.

I know of only one engine failure resulting from such an episode (in Australia at least) over many tens of thousands of hours flown. Most Garret failures seem to result from fuel quality issues and also FCU corrosion issues.

[Sean Dell]

I have 9000hrs (SH) and have never hit a bird (that I am aware of!).

Probably a bit lucky.

[Lucerne]

I would love a dollar for every one that I have hit. It makes you wince when you see a big one coming without room to avoid him!

[Helen49]

The records show that many serious and sometimes fatal accidents have been caused by bird strikes with 'other' parts of the aircraft......it's not just engine strikes which cause problems!

[Basil]

Went through a large flock of fieldfares one day. Aircraft looked like an explosion in a poultry shop but it was a Viscount with Dart turboprops (centrifugal compressors) so no problem.
May have been a different result in a turbojet. Their axial flow compressors are more sensitive to cascading flow breakdown.