Narrative:

Having been cleared to land; we were on short final to runway 27R in phl and spotted a vehicle proceeding west; down the runway about 1/2 way down. We commenced a go around and notified the tower of the vehicle. The tower controller gave us missed instructions and we came back around to land without further incident. After landing we were told by the tower the vehicle was not authority/authorized to be on the runway. Supplemental information from acn 772355: I was working local east; with responsibility for runways 35; 26; and 27R. Aircraft X was landing on runway 27R. I had just cleared a DH8 for takeoff on runway 35/K and was looking that direction when aircraft X said they were going around for a vehicle on the runway. I saw aircraft X in the go around (nose up) near the intersection of taxiway east and runway 27R; and just beyond taxiway north on runway 27R; a vehicle. The amass alerted after aircraft X initiated the go around and after I saw the vehicle. I instructed aircraft X to fly runway heading and maintain 3000 ft. I had never spoken to the vehicle or authority/authorized it to enter the runway.

Google
 

Original NASA ASRS Text

Title: EMB170 FLT CREW INITIATES GAR AFTER NOTICING A VEHICLE ON RWY 27R AT PHL. PHL LCL UNAWARE OF VEHICLE AND AMASS ALERTS AFTER GAR IS INITIATED.

Narrative: HAVING BEEN CLRED TO LAND; WE WERE ON SHORT FINAL TO RWY 27R IN PHL AND SPOTTED A VEHICLE PROCEEDING W; DOWN THE RWY ABOUT 1/2 WAY DOWN. WE COMMENCED A GAR AND NOTIFIED THE TWR OF THE VEHICLE. THE TWR CTLR GAVE US MISSED INSTRUCTIONS AND WE CAME BACK AROUND TO LAND WITHOUT FURTHER INCIDENT. AFTER LNDG WE WERE TOLD BY THE TWR THE VEHICLE WAS NOT AUTH TO BE ON THE RWY. SUPPLEMENTAL INFO FROM ACN 772355: I WAS WORKING LCL E; WITH RESPONSIBILITY FOR RWYS 35; 26; AND 27R. ACFT X WAS LNDG ON RWY 27R. I HAD JUST CLRED A DH8 FOR TKOF ON RWY 35/K AND WAS LOOKING THAT DIRECTION WHEN ACFT X SAID THEY WERE GOING AROUND FOR A VEHICLE ON THE RWY. I SAW ACFT X IN THE GAR (NOSE UP) NEAR THE INTXN OF TXWY E AND RWY 27R; AND JUST BEYOND TXWY N ON RWY 27R; A VEHICLE. THE AMASS ALERTED AFTER ACFT X INITIATED THE GAR AND AFTER I SAW THE VEHICLE. I INSTRUCTED ACFT X TO FLY RWY HDG AND MAINTAIN 3000 FT. I HAD NEVER SPOKEN TO THE VEHICLE OR AUTH IT TO ENTER THE RWY.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.