Cargo-plane bomb timed to explode on way to Philadelphia

A toner-cartridge bomb discovered in England on a plane bound for Philadelphia was set to detonate over the East Coast, British police announced Wednesday.

The explosion, timed for 5:30 a.m. on Oct. 29, would have happened well before UPS Flight 232 arrived in Philadelphia, reports suggest.

The bomb was found on a Boeing 767, which left East Midlands Airport, about 100 miles north of London, basically on time, arriving in Philadelphia at 7:01 a.m.

At 5:30 that morning, Flight 232 was actually about 160 miles northwest of Quebec City, on its way into Upper New York State, before flying through Eastern Pennsylvania and looping through South Jersey toward Philadelphia International Airport.

The daily flight, however, can arrive more a half-hour earlier, and often takes a more eastern path, coming down the Atlantic Coast, greatly extending the potential danger zone.

The earliest landing in Philadelphia in the past few months was 6:06 a.m. on Sept. 1. At 5:30 a.m. that day, the plane was roughly over Plymouth, Mass., according to FlightAware.

The plane seems not to have been one of the two UPS cargo planes whose search at Philadelphia International Airport that morning brought national attention to fears of a wider terror plot. The planes detained here were a Boeing 767 from Paris and an MD-11 from Cologne, Germany, according to UPS, Bloomberg reported.

A 767 from Midlands was also searched in Newark, N.J., as officials tried to determine if others flights carried dangerous packages.

No explosives were found on those three planes.

The British nearly missed the bomb. It fooled dogs, sophisticated screening equipment and even a police inspection of the printer itself - and the plane was cleared for takeoff to Philadelphia, according to reports.

Then British authorities learned of the discovery of a similar device, in a FedEx shipment from Yemen on a passenger plane in Dubai. Both packages were addressed to synagogues in Chicago. This time, the search was successful.

But soon the British mistakenly announced that the device was harmless, prompting speculation it was dummy meant to probe cargo-plane security.

The next day, the announcement came that the device could have blown up the plane.

The bomb used an odorless, colorless plastic explosive material called pentaerythritol tetranitrate or PETN, and a cell-phone circuit board, apparently functioning as a timer to spark a syringe of volatile powder to make the cartridge blow.

Authorities now believe that previous suspicious shipments headed for Chicago may have been test runs for these two bombs.

On Monday, the U.S. government announced that toner cartridges were banned from passenger flights.