Narrative:

While being vectored at 4000' for an ILS 22 to lga, approximately 22 mi on final, we were cleared for the approach. We were also told to cross 15 mi at 4000 and 3000' at 10 mi. At approximately 17 mi and 3500', approach control called us to ask what our altitude was. After we responded, we were reminded of our restriction and told to climb back to 4000', which we accomplished within approximately 1 mi. Remainder of approach was uneventful. The approach controller was very busy, even though the WX was VMC. The crossing restrictions were not entirely clear to us, but realizing the WX was VMC and cleared for the approach, what stuck in my head was that the next altitude was 3000'. Since we were given the crossing restrictions west/O the words, 'cross at or above,' the restriction was not very clear. But again, it didn't seem very important since we were cleared for the approach. I don't ever remember in my fling experience being cleared for an approach with such precise restrictions (i.e., cross 15 mi at 4000' + 10 mi at 3000', instead of at or above). Following the G/south down would have met those restrictions. But the controller, trying to ensure those specific crossing fixes were met, confused us by adding that to our instructions to shoot the approach. To sum up, it was an unusual clearance given in a very busy environment which we misunderstood.

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Original NASA ASRS Text

Title: ACR DESCENDS BELOW ASSIGNED ALT, MISSES CROSSING RESTRICTION.

Narrative: WHILE BEING VECTORED AT 4000' FOR AN ILS 22 TO LGA, APPROX 22 MI ON FINAL, WE WERE CLRED FOR THE APCH. WE WERE ALSO TOLD TO CROSS 15 MI AT 4000 AND 3000' AT 10 MI. AT APPROX 17 MI AND 3500', APCH CTL CALLED US TO ASK WHAT OUR ALT WAS. AFTER WE RESPONDED, WE WERE REMINDED OF OUR RESTRICTION AND TOLD TO CLB BACK TO 4000', WHICH WE ACCOMPLISHED WITHIN APPROX 1 MI. REMAINDER OF APCH WAS UNEVENTFUL. THE APCH CTLR WAS VERY BUSY, EVEN THOUGH THE WX WAS VMC. THE XING RESTRICTIONS WERE NOT ENTIRELY CLR TO US, BUT REALIZING THE WX WAS VMC AND CLRED FOR THE APCH, WHAT STUCK IN MY HEAD WAS THAT THE NEXT ALT WAS 3000'. SINCE WE WERE GIVEN THE XING RESTRICTIONS W/O THE WORDS, 'CROSS AT OR ABOVE,' THE RESTRICTION WAS NOT VERY CLR. BUT AGAIN, IT DIDN'T SEEM VERY IMPORTANT SINCE WE WERE CLRED FOR THE APCH. I DON'T EVER REMEMBER IN MY FLING EXPERIENCE BEING CLRED FOR AN APCH WITH SUCH PRECISE RESTRICTIONS (I.E., CROSS 15 MI AT 4000' + 10 MI AT 3000', INSTEAD OF AT OR ABOVE). FOLLOWING THE G/S DOWN WOULD HAVE MET THOSE RESTRICTIONS. BUT THE CTLR, TRYING TO ENSURE THOSE SPECIFIC XING FIXES WERE MET, CONFUSED US BY ADDING THAT TO OUR INSTRUCTIONS TO SHOOT THE APCH. TO SUM UP, IT WAS AN UNUSUAL CLRNC GIVEN IN A VERY BUSY ENVIRONMENT WHICH WE MISUNDERSTOOD.

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.