On December 11, 2008 about 1712 eastern daylight time, N924DL, a Boeing MD-88, operated by Delta Air Lines as flight 1102, a Title 14 CFR Part 121 scheduled domestic passenger flight, diverted to the Greenville Spartanburg International Airport (GSP), Greer, South Carolina after experiencing smoke in the cockpit while en route on a flight from Washington Dulles International Airport (IAD), Virginia to Atlanta Hartsfield Jackson International Airport (ATL), Atlanta, Georgia. Visual meteorological conditions prevailed in the area and an instrument flight rules flight plan had been filed. There were no injuries reported among either the crewmembers or passengers. The captain stated that all operations prior to smelling smoke were normal. He further stated that he first smelled smoke while level at 30,000 feet, just prior to making a normal descent for Atlanta. Shortly thereafter, he began to see smoke appear in the cockpit and donned oxygen masks while instructing the first officer to initiate the Smoke and Fumes Removal Checklist. Assuming the smoke to be “electrical in nature”, the captain further instructed the first officer to initiate the Smoke and Fumes Fire/Electrical checklist. According to the captain, at this point, he declared an emergency to FAA air traffic control, as the “smoke intensified”, and was given a clearance to divert to the Greenville airport. Shortly after touchdown the Captain noted that “some tires blew” upon initial application of the brakes, but he was “able to stop safely with the remaining tires.” Once stopped on the runway, the Captain shut down the engines. At this point the Fire Department notified the Captain that the “right brake assembly was on fire.” An emergency evacuation on the left side of the aircraft commenced. The first officer reported smelling traces of smoke before seeing “significant smoke” fill the cockpit. According to the first officer, after donning oxygen masks, he noted that “smoke was pouring out from the glare shield in front of my position and also appeared to be coming from below the glare shield between my legs.” After completing the Smoke and Fumes/Fire Electrical checklist, the first officer became “alarmed” when smoke did not cease from entering the cockpit after the left and right generators were turned off. Upon descending to 10,000 feet, the first officer depressurized the aircraft using the cabin manual control wheel, which he said cleared the cabin of smoke “quickly.” During the course of the emergency, one of the flight attendants was notified by the captain that they were going to make a precautionary landing at an airport “short of Atlanta” due to smoke in the cockpit. A few moments later the captain notified the flight attendant that they were going to be making an emergency landing in Greenville, South Carolina, but “not to the point of an evacuation", and the flight attendants proceeded to secure the cabin for landing. Upon touching down in Greenville, South Carolina, a flight attendant reported hearing “a loud explosion in the back of the aircraft.” After shutdown, the captain ordered an emergency evacuation out of the left side of the aircraft, and the flight attendants complied with his orders. On-site postincident examination of the incident aircraft in Greenville, South Carolina, revealed overheating and smoke damage to the DC Ground Service Tie Relay (R2-51) and Blocking Diode Assemblies (R7-50 and R7-51), located in the forward accessory compartment. The two components were subsequently removed from the aircraft and sent to the National Transportation Safety Board’s material laboratory in Washington, DC, for further analysis. On January 8, 2009, a detailed examination of the components revealed internal damage consistent with there having been arcing of the electrical contacts, but due to the extent of the damage, no other specifics related to the arcing could be ascertained.