Narrative:

I was the PF from iad to fll. We were on the mrlin 4 arrival inbound to fll. We were tracking in on the virginia key (vkz) 029 degree radial. At about 60 mi from vkz at 12000 ft MSL, we were told to cross 30 mi out of fll at 7000 ft. I looked at the STAR and saw that mrlin intersection says expect to cross that at 7000 ft. We leveled off at 7000 ft and 1 min later ATC came back and said we should be at 9000 ft. We climbed back to 9000 ft and nothing was ever said again. With fll landing on runway 27R and mrlin intersection expected to be crossed at 7000 ft, our original clearance would have made sense. As the PF, I had read back the descent clearance to ATC, since the captain was on the PA. I don't know whether ATC or myself goofed, but the situation was unclr.

Google
 

Original NASA ASRS Text

Title: AN AIRLINE B737-200 CREW DSNDED BELOW THEIR ASSIGNED ALT BECAUSE THEY WERE EXPECTING TO CROSS A WAYPOINT AT THE LOWER ALT. AN ALERT RADAR CTLR HAD THEM RETURN TO THEIR ASSIGNED ALT.

Narrative: I WAS THE PF FROM IAD TO FLL. WE WERE ON THE MRLIN 4 ARR INBOUND TO FLL. WE WERE TRACKING IN ON THE VIRGINIA KEY (VKZ) 029 DEG RADIAL. AT ABOUT 60 MI FROM VKZ AT 12000 FT MSL, WE WERE TOLD TO CROSS 30 MI OUT OF FLL AT 7000 FT. I LOOKED AT THE STAR AND SAW THAT MRLIN INTXN SAYS EXPECT TO CROSS THAT AT 7000 FT. WE LEVELED OFF AT 7000 FT AND 1 MIN LATER ATC CAME BACK AND SAID WE SHOULD BE AT 9000 FT. WE CLBED BACK TO 9000 FT AND NOTHING WAS EVER SAID AGAIN. WITH FLL LNDG ON RWY 27R AND MRLIN INTXN EXPECTED TO BE CROSSED AT 7000 FT, OUR ORIGINAL CLRNC WOULD HAVE MADE SENSE. AS THE PF, I HAD READ BACK THE DSCNT CLRNC TO ATC, SINCE THE CAPT WAS ON THE PA. I DON'T KNOW WHETHER ATC OR MYSELF GOOFED, BUT THE SIT WAS UNCLR.

Data retrieved from NASA's ASRS site as of July 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.