Lomapaseo:
Please excuse my poor communication of the issue of the regulatory impact of the change to 250 knots, I obviously did not get the message across that I wanted.
The message I was trying to communicate is that regulators involved with strike impact certfication were not as concerned with the issue of striking larger birds because they believed that one of the mitigations being used was to limit the IAS to 250 KIAS on climb. Not so in many jurisdictions.
I am fully aware of the FAR 25 requirements and indeed the FAR you quoted is only applicable to the empennage (as the result of a 1962 Viscount crash). The rest of the structure is only certified for a 4 lb bird. My analysis did take into account the use of Vc for the impact speed and the examples I cite were based on a Vc of 320 knots and a 4 lb bird.
Thanks for posting the explanation on blade loading and airspeed. I am well aware of this issue, but believe it is valuable for others to understand the concept. One very important issue is the fact that other than the ultra-large fan engines on the B777 that were voluntarily certified for an 8 lb bird, the current engines being used in the overwhelming majority of aircraft are only certified for a 4 lb bird. The weights of migratory waterfowl are well above this and high speed operations do present a high risk to engine structures.
One point I forgot to mention is the issue of the aircraft acceleration manever - from 250 knots to high speed climb. During this maneuver rate of climb typically is reduced by 50%. The aircraft is accelerating, climb rate is reduced and all this occurs at the bird rich altitudes. Therefore, the classic high risk is occurring - exposure, probability and severity are all increasing.
There have been enough recent incidents with geese where the aircraft structure has been damaged extensively, bordering on catatstrophic failure, that to increase the speed at low altitude is foolhardy.