"Was it a Black Hawk?" I asked. The dad wasn't sure. They eyes of his son reflected more certainty.

But nothing was certain that day -- except for the deep blue of the sky, the warmth of the day and the overall success of Town Day.

As for the Black Hawk, The promised display near Arlington High School, arranged by a Pop Warner father, didn't come off. Selectman Diane Mahon had written to the Arlington e-mail list that its schedule had changed from 11 a.m. to 4 p.m. on Saturday, Sept. 20, to an earlier time. She had added that the 'copter would not land but only fly over, but I had missed that. Details about the reasons for the change in plans remained murky.

Feeling a bit insecure, I watched some of the AHS-Burlington freshman football game and then walked toward Town Day, just underway. At Mass. Ave. and Mill, I asked an Arlington officer directing traffic what he knew about the helicopter event. "Didn't happen," he said, adding he didn't know why.

That night, I asked Chief Fred Ryan about it by e-mail. In terse responses sent via BlackBerry, he wrote that the Arlington Police security detail for the landing of the military helicopter was canceled. He wrote that no reason was given and that Mahon had a role in the cancellation.

By the following Monday, Mahon explained that she had received a call Paul Cahill, Pop Warner president, who said the U.S. Army had told him the town did not get permission because of incomplete paperwork and that the Army could do only a flyover. "Since that was the case, I canceled the police details because there, basically, was no event, just the flyover," she said.

She said she was trying to arrange the event for Veterans' Day.

Thus, I concluded, the event was not canceled because of a discussion on the Arlington e-list questioning why a militaristic event was scheduled for Town Day or that some undefined pressure was brought to bear on town officials. The answer was much more mundane: incomplete paperwork.

So the week before Town Day was full of insecurity for our nation, as market panic spurred a $700 billion bailout plan, events that we can expect to see trickle down to Arlington's economy.

To escape the feeling, I melted into the growing Mass. Ave. throng and enjoyed the vault of blue protecting Arlington Town Day. Protected by activities and food and music and causes and friendly faces -- this was security enough for a day.