Regional Jet 200 ER/LR (CRJ200)
Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Conflict NMAC
General None Reported / Taken
Human Factors
We just started descending from FL190 per ATC clearance when at about FL180 we came within a very close distance to what looked like several (3 or more) silver/blue balloons with a large box (looked black) hanging from it. They were not the store bought type balloons; rather; much larger. It was difficult to tell from the cockpit as to whether the balloons were climbing or descending; but I believe they were traveling with the winds aloft (approx 350/40). We notified ATC of the balloons.From my view from FD; balloons passed less than 50ft from left wing and less than 50 ft of altitude. I was ready to correct course; altitude but the timing of event was rapid. By the time I recognized balloons and turned off autopilot balloons were at 9 O'clock position to left wing.[suggestion] Require balloons traveling into controlled airspace to be equipped with transponders.
CRJ-200 Captain reported an NMAC with a cluster of balloons at FL180 on descent into PHL.