Narrative:

Restricted area 2501 was released FL270 and above. I had one heavy air carrier on frequency at FL270 over the restricted area. Air carrier X; also a heavy; checked on at FL270 over the restricted area. Both airplanes were landing lax on the riivr arrival. At the same time; the uret slew ball was being replaced by tech-ops and there was a bit of distraction in the immediate area of my sector. When the first heavy cleared the restricted area; I gave him a clearance to cross gramm at and maintain FL190. Apparently air carrier X read back the clearance and started descending. I did not hear this and thought it was the first heavy that read back the clearance. Within a few seconds; I noticed that air carrier X was below FL270 and descending into the restricted area. I told air carrier X to maintain FL270; and then asked him when he got descent. He said he was climbing back up and that I had given him gramm at FL190. Recommendation; listen more carefully when equipment is being repaired or when the sector is closed or moved to another position.

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Original NASA ASRS Text

Title: Distracted by an equipment repair; a ZLA Controller missed an incorrect altitude assignment read back that resulted in an airspace entry infraction.

Narrative: Restricted Area 2501 was released FL270 and above. I had one Heavy Air Carrier on frequency at FL270 over the restricted area. Air Carrier X; also a heavy; checked on at FL270 over the restricted area. Both airplanes were landing LAX on the RIIVR arrival. At the same time; the URET slew ball was being replaced by tech-ops and there was a bit of distraction in the immediate area of my sector. When the first Heavy cleared the restricted area; I gave him a clearance to cross GRAMM at and maintain FL190. Apparently Air Carrier X read back the clearance and started descending. I did not hear this and thought it was the first Heavy that read back the clearance. Within a few seconds; I noticed that Air Carrier X was below FL270 and descending into the restricted area. I told Air Carrier X to maintain FL270; and then asked him when he got descent. He said he was climbing back up and that I had given him GRAMM at FL190. Recommendation; listen more carefully when equipment is being repaired or when the sector is closed or moved to another position.

Data retrieved from NASA's ASRS site as of April 2012 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.