airfoilmod;
Re, "As Humans we overestimate our importance to the Planet, vis-a-vis survival. We can't kill it, it can kill us."
No kidding! Another thread of course, but "profound indifference" comes to mind when notions such as "human progress" and "human survival" are raised in the same breath as "the", (not "our"), planet. We could disappear due to our activities or through other natural occurence and there wouldn't be so much as the slightest quiver on earth, so indifferent is it to our continued and incidental existence. It will carry on, perhaps changed due to what we have done to the accidentally congenial environment in which we evolved, without intention, without direction, and without us, as it did before we arrived 3 billion years ago.
protectthehornet;
Re, "Contrary to the other answers you received, I believe the answer is yes, you can maneuver an airliner and avoid birds. I've even reminded my colleagues of the maneuver and they seem to agree. I've decided not to publish my maneuver here, but should the need arise, I would certainly use it. I think it would be quite easy if you had a true 3 seconds."
On takeoff, in general, the possibility of avoiding birds if one sees them in time, is there. I know of several takeoffs in which the pitch attitude has either been flattened or increased sufficiently to decrease/increase rates of climb right after liftoff, with good success and safety, and well within the performance capabilities of the aircraft in the 2nd segment climb phase.
That said, let us examine the question of bird avoidance using known facts about eyes, speed and mass:
From a discussion on depth of field, (image sharpness, not resolution), and why it works in photography, by Ansel Adams in his Basic Photo Series, the human eye, he states, generally cannot resolve any image sensed by the retinal structure (rods, cones) that is less than 100th of an inch in length (as projected on the retina). Obviously distance and object size determine the angle subtended and the consequent image size projected onto the retina but if the distance between light-sensing rods/cones is less than the size of the image as focussed by the lens/iris, it literally cannot be seen where there are no "sensors".
An imperfection in a photographic negative known as "out of focus" is known as a "circle of confusion" and will appear as a tiny blob instead of as a sharp pinpoint. An image, (retinal or photographic - same principles) is made up of points of light - our eyes are able to focus only very narrowly so our depth of field is small, and sharpness of the image only occurs in a very tiny area in the center of our field of view. Peripheral vision can sense motion and color but cannot focus sharply.
So, if that tiny blob on the photographic film, the CCD of a digital camera or our retinas is less than 1/100th of an inch in diameter, the image is perceived as "sharp" by the eye and therefore the mind.
A large goose 1000ft ahead of the aircraft will not be seen by the human eye because it's size that far away subtends an angle which is too narrow to project an image onto the retina larger than 1/100th of an inch - the eye is blind to the "dots" that are large geese 1000ft away. All we have to do to consider this is to draw, in our mind's eye, two lines from the body of a large goose 1000ft away and imaging, through an intuitive comprehension of trigonometry, the angle subtended by these two lines and image the size of the image thereby generated on the retina.
If we instead choose the size of a flock of geese, we may see it as a whole in which case the chances of avoidance are increased slightly.
At the initial climb speed of the A320, accelerating through about 180kts (above 1500ft AGL at the time of the collision), the aircraft is doing about 300fps, (feet per second).
I know you know this but for reference for others, 250kts is 420fps, 300kts is 505fps and 350kts is 590fps.
Now, that's all "Calibrated Airspeed" - TAS's will be higher, again as you know. For example, a pilot who chooses to fly at 250kts IAS below 10,000ft in descent may actually be doing close to 300kts, "physically" through the air depending upon temperature and pressure of the air, (wind and therefore groundspeed are obviously not factors!) and, given the per-squared law, will be meeting any object at 500fps and the energy commensurate with the mass so encountered - again, you've menioned this so I know you know this.
You have correctly pointed out that a pilot who has spotted birds ahead may have, at "lower speeds", (flaps extended speeds), up to 3 seconds for "avoidance" but I would disagree that this can be done at 420fps (250kts) only because of the above reason...the birds cannot be seen in time at that speed and one does not have 3 seconds at 500fps but perhaps 1 to 1.5 second(s) at best.
Airliners do not maneuver quickly not only because of mass/weight but because they are travelling so fast and require, as any aircraft does regardless of mass, very high bank angles at such speeds to achieve a high rate of turn. Thus, for passenger comfort, unless it is an emergency survival maneuver, an increase and especially a (negative 'g') decrease in rate of climb or altitude is attended by significant 'g' loads which can present risk to those in the back, the only maneuver left that is not attended by such forces is roll, and of course even that would not be for turning out of the way (given the physics of turning at high speed described) but would be for momentarily presenting a smaller (banked frontal profile to what we assume would be a mainly horizontal formation of larger birds. (That said, seagulls don't flock or fly like that).
These notions and one solution are not unusual but are not present in any SOPs, AOMs or unofficial techniques I have read anywhere. One is in test pilot territory beyond 45deg of bank in airline work, notwithstanding the captain's authority to take any action he or she deems necessary to preserve life and property.
The Airbus 320/340 series will not exceed a 45deg bank angle without holding the stick in the roll-command position. But it will do just over 60deg of bank if held there manually. C* laws will not permit further bank angles.
The conclusions I would like to draw here are:
1. The human eye is incapable of resolving images smaller than 100th of an inch such that size, vector (speed and direction) and altitude can be determined with accuracy. Birds that can do substantial damage to an aircraft are still not large enough for the human eye to see from 1500ft or 3 seconds away at 300kts. Even at 300fps, that only leaves 5 seconds for reaction.
2. That at typical jet transport speeds even below 10,000ft, avoidance of birds when such are spotted, "even in time", is not a certain exercise and will always have an unpredictable outcome.
3. That the per-squared law guarantees that at higher speeds damage is likely to be exponentially worse depending upon where on the airframe the strike occurs.
4. I think the term "playing with fire" is appropriate where a crew chooses to exceed the legal 250kt speed limit below 10,000ft when descending.
As discussed earlier in this thread, the "elasticity" of flesh rapidly reduces with higher speeds so the "splat" factor is higher at low speeds and spreads the impact loads over a wider area. At high speeds the flesh mass is concentrated in a smaller area because it does not have time to splat, or spread out, so the impact is just like taking a very heavy, very fast sledge hammer to aircraft skin, engines or windshield - the equivalent of over 100,000lbs of force which has to be absorbed by the airframe, etc.
As far as I know, there is no waiver or relief in descent except if a higher speed is required to remain clean. I know that for the B777-300, the max clean speed at MTOW is approximately 264kts so it is highly unlikely that any heavy transport needs to exceed the speed limit to remain clean while descending into the terminal area.
All this said, birdstrikes are part of the inevitability of aviation, mitigated by knowledge, regulatory compliance and airmanship.