On a cloudless spring day, the NYPD helicopter soars over the city, its sights set on the Statue of Liberty. The helicopter's unmarked paint job belies what's inside: an arsenal of sophisticated surveillance and tracking equipment powerful enough to read license plates — or scan pedestrians' faces — from high above the nation's largest metropolis.

Police say the chopper's sweeps of landmarks and other potential targets are invaluable in helping guard against another terrorist attack, providing a see-but-avoid-being-seen advantage against bad guys. "It looks like just another helicopter in the sky," said Assistant Police Chief Charles Kammerdener, who oversees the department's aviation unit.

The chopper is named simply "23" — for the number of police officers killed in the Sept. 11, 2001, attacks.

A US federal appeals court on Tuesday ruled that the country's one-sized paper money discriminates against the blind and told the government to change the currency's size and texture. The court upheld a previous ruling in November 2006 by federal Judge James Robertson who had ordered the Treasury Department to find a way to accommodate the more than three million visually-impaired Americans who have trouble distinguishing the different US denominations which are all the same size and color. By a vote of two to one, the appeals court agreed with the earlier decision favoring the American Council of the Blind and referred the case back to Robertson to examine practical steps to be taken. "A large majority of other currency systems have accommodated the visually impaired, and the (treasury) secretary does not explain why US currency should be any different," the court said in its ruling.