Re: How is it different
"if a pilot sees them, he can avoid them."
The odds of a pilot seeing birds on a collision course are slim to negligable. As I understand it Sully and his copilot caught a glimpse of the flock just as it went under their nose.
I went head-on into a duck squadron and only saw the one which just avoided being propellor mincemeat for about a tenth of a second as it flared and went above me. I never saw the one that (slightly) dented the wing's leading edge, but well and truely felt it - and the closing speed was only about 120mph. Airliners are flying a _LOT_ faster than that, with higher pilot loadings when in the pattern and significantly less time to identify an (effectively) near-stationary object in the sky in front of you.
the same applies to drones. They're small, slow and bloody hard to see - which is why I take all reported sightings with a large dose of cynicism, especially when you take into account that the number of "drone sightings" at Heathrow and other airports has an almost 1:1 correspondance with the decrease in the number of "bird sightings" - and having watched cranes and other large birds hanging around the streams on the south side of Heathrow, then flying north over the runways I know what I'm putting my money on as the more likely culprit for most sightings.
_ANY_ transport pilot who claims that a drone tracked alongside their aircraft should be given as much credence as one who saw a UFO with Roswell Greys waving out the window at them. They may have seen something, but it wasn't what they think it was. Even racing drones can't go that fast and racing drones can only keep it up for a few seconds.