Narrative:

Air carrier X, widebody transport, was eastbound at FL390, en route to msp, but deviating south of course for a thunderstorm east of rap. As the sector 35 controller, I had approved FL390 wafdof due to WX, but new information on a wbound flight from ZMP, also at FL390 and deviating around the same storm, prompted a call from me to sector 32 to request air carrier X at FL370 for traffic. Sector 32 called me back and advised air carrier X wanted to climb to FL410 with a 20 degree right turn for traffic. I approved the request. At approximately XX45Z, sector 32 called to advise that air carrier X had declared an emergency due to engine failure and was descending to FL370, requesting FL240. Air carrier X checked on my frequency descending to FL370 and requested FL240. I cleared air carrier X to FL350 and called traffic 7 O'clock, 3 mi, eastbound. Additional traffic was a wbound flight at FL310 and virtually all aircraft were deviating from their filed routes due to the storm east of rap and another area of WX over onl. I told air carrier Y at FL330 to turn 30 degree left to clear the emergency aircraft's descent path. The pilot hesitated just a bit due to the proximity of the storm off his left wing, but said that he would turn as far north as possible. I turned the FL310 traffic to heading 200 to clear the projected descent path. Air carrier X again requested FL240 and I advised unable due to traffic 6 O'clock, 4 mi. Air carrier X answered with, 'well, move him!' I advised that turns had been issued. 60-90 seconds later, when air carrier Y was 5 NM and diverging, I cleared air carrier X to FL240. The pilot acknowledged and said that he would try a restart out of FL260 and requested direct rwf. I reclred air carrier X to msp direct rwf, direct, coordinated with the ZMP sector 35 controller, and shipped the aircraft to ZMP. All in all, the incident went smoothly. I am concerned, however, that the pilot did not seem to understand that although I could not legally clear him for lower without providing standard separation with air carrier Y flight at FL330, he could exercise his authority to deviate from his last clearance as PIC of an aircraft in emergency and continue his descent. This is why I kept issuing traffic. Perhaps this item could be reviewed in 'callback' as a reminder to pilots that ATC cannot issue clrncs that would provide less than standard separation, but we will provide all information necessary for a pilot to exercise his authority to fly his aircraft in the safest possible manner in a given situation, eg, providing traffic/terrain advisories.

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Original NASA ASRS Text

Title: ACR IN AN EMERGENCY DESCENT DUE TO ENGINE FAILURE WAS HELD AT INTERIM ALT BECAUSE OF CONFLICTING TRAFFIC.

Narrative: ACR X, WDB, WAS EBND AT FL390, ENRTE TO MSP, BUT DEVIATING S OF COURSE FOR A TSTM E OF RAP. AS THE SECTOR 35 CTLR, I HAD APPROVED FL390 WAFDOF DUE TO WX, BUT NEW INFO ON A WBOUND FLT FROM ZMP, ALSO AT FL390 AND DEVIATING AROUND THE SAME STORM, PROMPTED A CALL FROM ME TO SECTOR 32 TO REQUEST ACR X AT FL370 FOR TFC. SECTOR 32 CALLED ME BACK AND ADVISED ACR X WANTED TO CLIMB TO FL410 WITH A 20 DEG RIGHT TURN FOR TFC. I APPROVED THE REQUEST. AT APPROX XX45Z, SECTOR 32 CALLED TO ADVISE THAT ACR X HAD DECLARED AN EMER DUE TO ENGINE FAILURE AND WAS DESCENDING TO FL370, REQUESTING FL240. ACR X CHECKED ON MY FREQ DESCENDING TO FL370 AND REQUESTED FL240. I CLRED ACR X TO FL350 AND CALLED TFC 7 O'CLOCK, 3 MI, EBND. ADDITIONAL TFC WAS A WBOUND FLT AT FL310 AND VIRTUALLY ALL ACFT WERE DEVIATING FROM THEIR FILED ROUTES DUE TO THE STORM E OF RAP AND ANOTHER AREA OF WX OVER ONL. I TOLD ACR Y AT FL330 TO TURN 30 DEG LEFT TO CLEAR THE EMER ACFT'S DSCNT PATH. THE PLT HESITATED JUST A BIT DUE TO THE PROX OF THE STORM OFF HIS LEFT WING, BUT SAID THAT HE WOULD TURN AS FAR N AS POSSIBLE. I TURNED THE FL310 TFC TO HDG 200 TO CLEAR THE PROJECTED DSCNT PATH. ACR X AGAIN REQUESTED FL240 AND I ADVISED UNABLE DUE TO TFC 6 O'CLOCK, 4 MI. ACR X ANSWERED WITH, 'WELL, MOVE HIM!' I ADVISED THAT TURNS HAD BEEN ISSUED. 60-90 SECONDS LATER, WHEN ACR Y WAS 5 NM AND DIVERGING, I CLRED ACR X TO FL240. THE PLT ACKNOWLEDGED AND SAID THAT HE WOULD TRY A RESTART OUT OF FL260 AND REQUESTED DIRECT RWF. I RECLRED ACR X TO MSP DIRECT RWF, DIRECT, COORDINATED WITH THE ZMP SECTOR 35 CTLR, AND SHIPPED THE ACFT TO ZMP. ALL IN ALL, THE INCIDENT WENT SMOOTHLY. I AM CONCERNED, HOWEVER, THAT THE PLT DID NOT SEEM TO UNDERSTAND THAT ALTHOUGH I COULD NOT LEGALLY CLEAR HIM FOR LOWER WITHOUT PROVIDING STANDARD SEPARATION WITH ACR Y FLT AT FL330, HE COULD EXERCISE HIS AUTHORITY TO DEVIATE FROM HIS LAST CLRNC AS PIC OF AN ACFT IN EMER AND CONTINUE HIS DSCNT. THIS IS WHY I KEPT ISSUING TFC. PERHAPS THIS ITEM COULD BE REVIEWED IN 'CALLBACK' AS A REMINDER TO PLTS THAT ATC CANNOT ISSUE CLRNCS THAT WOULD PROVIDE LESS THAN STANDARD SEPARATION, BUT WE WILL PROVIDE ALL INFO NECESSARY FOR A PLT TO EXERCISE HIS AUTHORITY TO FLY HIS ACFT IN THE SAFEST POSSIBLE MANNER IN A GIVEN SITUATION, EG, PROVIDING TFC/TERRAIN ADVISORIES.

Data retrieved from NASA's ASRS site as of August 2007 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.