Two things about B-Air--
The first hit sends people up (however slight) and the second one hits them at a 60-degree angle. As a result, Falco could just Forward-B again before hitting the ground.
Also, part of why the N-Air spike is so important is because it sends people down in a way that makes it impossible to interact with the stage (like, if you spiked someone next to a wall, they couldn't tech it), so they stay in their falling animation for a while before the RCO lag even becomes a factor. B-Air doesn't do that, so you would be hard-pressed to get a U-Smash out of it even if it did guarantee a landing, but N-Air spike gives you plenty of time.
Retro put up a video that had a similar concept a long, long time ago, but it wasn't explored with RCO lag in mind. Let me see if I can find it...
EDIT: Yeah, here you go--
http://www.youtube.com/watch?v=EzPFNPrhJV4
The first hit sends people up (however slight) and the second one hits them at a 60-degree angle. As a result, Falco could just Forward-B again before hitting the ground.
Also, part of why the N-Air spike is so important is because it sends people down in a way that makes it impossible to interact with the stage (like, if you spiked someone next to a wall, they couldn't tech it), so they stay in their falling animation for a while before the RCO lag even becomes a factor. B-Air doesn't do that, so you would be hard-pressed to get a U-Smash out of it even if it did guarantee a landing, but N-Air spike gives you plenty of time.
Retro put up a video that had a similar concept a long, long time ago, but it wasn't explored with RCO lag in mind. Let me see if I can find it...
EDIT: Yeah, here you go--
http://www.youtube.com/watch?v=EzPFNPrhJV4