Narrative:

We were holding at the grace intersection at 10000 and given an efc time of about 30 minutes. There were other aircraft holding in 1000' increments above us and one aircraft 1000' below us. I was on the PA telling the passenger about our holding delay and expected arrival time at the gate. The aircraft was on autoplt and was coupled to the FMC to keep us in the hold at grace. The captain received a descent clearance to 9000' and reset the altitude window in the autoplt. I did not notice this and did not hear the clearance since I was talking on the PA. Shortly after I had finished talking, approach control called and asked if we had started our descent yet, and then called out a traffic advisory. The captain remarked that we had been clrd to 9000' and I immediately descended to that altitude. I don't know whether our delayed descent caused a traffic conflict. The controller did not say so. Most capts I have flown with have whoever is flying that particular leg, make all the passenger announcements. You cannot monitor the ATC radio while doing this, so consequently the person flying the aircraft is temporarily out of the communications loop. The pilot not flying doesn't usually take over control of the aircraft while the other pilot is on the PA, so you have to remember to update the pilot flying on any changes while he was off the radio. Perhaps a better technique would be to have the pilot flying monitor the ATC frequency and the pilot not flying to make the passenger announcements.

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Original NASA ASRS Text

Title: MLG IN THE HOLD DID NOT DESCEND AS CLEARED.

Narrative: WE WERE HOLDING AT THE GRACE INTXN AT 10000 AND GIVEN AN EFC TIME OF ABOUT 30 MINUTES. THERE WERE OTHER ACFT HOLDING IN 1000' INCREMENTS ABOVE US AND ONE ACFT 1000' BELOW US. I WAS ON THE PA TELLING THE PAX ABOUT OUR HOLDING DELAY AND EXPECTED ARRIVAL TIME AT THE GATE. THE ACFT WAS ON AUTOPLT AND WAS COUPLED TO THE FMC TO KEEP US IN THE HOLD AT GRACE. THE CAPT RECEIVED A DSCNT CLRNC TO 9000' AND RESET THE ALT WINDOW IN THE AUTOPLT. I DID NOT NOTICE THIS AND DID NOT HEAR THE CLRNC SINCE I WAS TALKING ON THE PA. SHORTLY AFTER I HAD FINISHED TALKING, APCH CTL CALLED AND ASKED IF WE HAD STARTED OUR DSCNT YET, AND THEN CALLED OUT A TFC ADVISORY. THE CAPT REMARKED THAT WE HAD BEEN CLRD TO 9000' AND I IMMEDIATELY DESCENDED TO THAT ALT. I DON'T KNOW WHETHER OUR DELAYED DSCNT CAUSED A TFC CONFLICT. THE CTLR DID NOT SAY SO. MOST CAPTS I HAVE FLOWN WITH HAVE WHOEVER IS FLYING THAT PARTICULAR LEG, MAKE ALL THE PAX ANNOUNCEMENTS. YOU CANNOT MONITOR THE ATC RADIO WHILE DOING THIS, SO CONSEQUENTLY THE PERSON FLYING THE ACFT IS TEMPORARILY OUT OF THE COMMUNICATIONS LOOP. THE PLT NOT FLYING DOESN'T USUALLY TAKE OVER CONTROL OF THE ACFT WHILE THE OTHER PLT IS ON THE PA, SO YOU HAVE TO REMEMBER TO UPDATE THE PLT FLYING ON ANY CHANGES WHILE HE WAS OFF THE RADIO. PERHAPS A BETTER TECHNIQUE WOULD BE TO HAVE THE PLT FLYING MONITOR THE ATC FREQ AND THE PLT NOT FLYING TO MAKE THE PAX ANNOUNCEMENTS.

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.