Date: 201306
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Aircraft: B757-300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Descent
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Other / Unknown
Second reporter function: Pilot Not Flying; Captain
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Critical; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control; Person Flight Crew
Result: General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: A B757 was an overflight who I believe departed enroute to the east at FL370. I was working [Sector X] and [Sector Y] combined which is a low sector that feeds [the airport]. Aircraft reported emergency with a possibly fire in the galley and smoke in the cabin with the controller working the sector above me. They called me and notified me of the emergency. I told the Controller to turn [the B757] direct to [the airport] and RADAR contact. I then called TRACON to coordinate the emergency and told them the aircraft would be descending to 100 and released control on contact. Later when the B757 checked on descending to FL240 I descended him to 100 and gave him an altimeter setting and got some other information. [The airport] descended at a very rapid rate and descended through a 10;200 MVA block in my sector. By the time I realized this; he was just about out of the block. I should have been more aware of his descent rate and also should have assigned [the B757] 11;000 until laterally clear of the MVA of 10;200. I assumed the aircraft would clear the MVA but I shouldn't have assumed anything.


Second narrative: We received a call from mid-cabin informing us of electric smelling smoke from mid-galley. Flight Attendant would call us back when they had more information and I responded; 'Keep us posted'. Two minutes; or less; we received second call that smoke was getting worse and that it was coming from one of the galley ovens. She stated to me that they had turned off power. I told her to pull circuit breaker and asked her if she thought it could be food or something else; and her reply was that smell was electrical; so I again told her to 'keep us posted'. I turned off the galley utility busses. Upon hanging up; my First Officer and I discussed possibility of diverting. I decided to hold off until we heard more information and that if it got worse we would declare an emergency divert. Approximately two minutes later we got call from mid-cabins' Flight Attendant (with Captain's speaker on); she stated that we had a 'severe' situation and the black smoke was getting 'worse'. At the same time I made eye contact and acknowledged to my First Officer to declare an emergency and divert. I informed Flight Attendant that we were diverting and declaring an emergency with 20 minutes until landing. The Flight Attendant then said 'I don't think we need to divert'. I responded that I already had made the decision to divert and I had declared an emergency. Upon hanging up; once again; I confirmed with my First Officer that we had declared emergency and diverting; he acknowledged and that we were cleared to descend to FL230; I proceeded to send a ACARS call me message to Dispatch. A minute later I re-sent the ACARS with a 7700 message. Dispatch contacted me immediately and I informed them that we had declared emergency and diverting because we had smoke in the cabin. Dispatch acknowledged by saying 'Roger' and they would call for equipment and inform the station. We prepared the aircraft for landing and in order to expedite landing we flew faster than 250 KTS below 10;000 FT. I continued communication with flight attendants to check on situation and they advised me that smoke started to dissipate. Upon landing First Officer called to the back to get update and flight attendants informed us that things were getting back to normal. We also asked ATC if they saw any smoke from outside airplane and they said no. We continued taxiing to gate and asked our passengers to remain seated to have the fire crew evaluate situation.


Synopsis: Enroute Controller described a MVA infraction when issuing a descend to an emergency Air Carrier with a possible cabin fire. The reporter did not expect the rapid descent toward the diversion airport.