Narrative:

My first officer had been flying the plane when we were cleared by dayton approach for the ILS for runway 24R. The controller told us to maintain 3000 ft until established, which I repeated back, and then I switched over to tower as instructed. My first officer, however, thought he had said 2000 ft and as he was joining the localizer, he continued his descent through 3000 ft. I thought he was descending down to the initial approach altitude of 2600 ft since we were established and didn't know that he had 2000 ft set in his mind. Just as I noticed what he was doing and said something, dayton tower informed us that we had set off an altitude alert because we were too low for the approach. My first officer had reached about 2200 ft at this time and was correcting by quickly climbing back up to 2600 ft. I stated we were at 2600 ft and he cleared us to land. We had ground contact the entire time and were able to fly and land visually. A better review of the approach plate, in particular the initial approach altitude, whether conditions are VMC or IMC, would prevent a recurrence. Supplemental information from acn 484650: I was the flight engineer on a flight from jax to day. Once in the day airspace, we were cleared for the ILS approach to runway 24R and down to 3000 ft. 3000 ft was set into the altitude alert by the captain, as the first officer was flying the aircraft. During the descent, I was busy scanning the engineer panel and setting up the engine xfeed to the proper confign. Looking back forward at the instruments, I saw that we were passing through 2500 ft MSL. I then checked the first officer's altitude indicator and saw that we were well below GS. I was about to inform the first officer of this when dayton tower called and said he was getting a low altitude alert and that we were to climb. The captain replied that we were correcting to 2600 ft. The first officer then acquired the GS, and an uneventful landing ensued. The WX was reported as 210 degrees/4 KTS, 5 mi mist, 6 mi scattered, 47 mi scattered, 80 mi overcast, 22/21/30.15. We broke out of the cloud coverage and acquired the runway visually at approximately 1500 ft MSL and 5 mi.

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Original NASA ASRS Text

Title: B727 CREW DSNDED BELOW CLRED ALT ON THE RWY 24R ILS AT DAY.

Narrative: MY FO HAD BEEN FLYING THE PLANE WHEN WE WERE CLRED BY DAYTON APCH FOR THE ILS FOR RWY 24R. THE CTLR TOLD US TO MAINTAIN 3000 FT UNTIL ESTABLISHED, WHICH I REPEATED BACK, AND THEN I SWITCHED OVER TO TWR AS INSTRUCTED. MY FO, HOWEVER, THOUGHT HE HAD SAID 2000 FT AND AS HE WAS JOINING THE LOC, HE CONTINUED HIS DSCNT THROUGH 3000 FT. I THOUGHT HE WAS DSNDING DOWN TO THE INITIAL APCH ALT OF 2600 FT SINCE WE WERE ESTABLISHED AND DIDN'T KNOW THAT HE HAD 2000 FT SET IN HIS MIND. JUST AS I NOTICED WHAT HE WAS DOING AND SAID SOMETHING, DAYTON TWR INFORMED US THAT WE HAD SET OFF AN ALT ALERT BECAUSE WE WERE TOO LOW FOR THE APCH. MY FO HAD REACHED ABOUT 2200 FT AT THIS TIME AND WAS CORRECTING BY QUICKLY CLBING BACK UP TO 2600 FT. I STATED WE WERE AT 2600 FT AND HE CLRED US TO LAND. WE HAD GND CONTACT THE ENTIRE TIME AND WERE ABLE TO FLY AND LAND VISUALLY. A BETTER REVIEW OF THE APCH PLATE, IN PARTICULAR THE INITIAL APCH ALT, WHETHER CONDITIONS ARE VMC OR IMC, WOULD PREVENT A RECURRENCE. SUPPLEMENTAL INFO FROM ACN 484650: I WAS THE FE ON A FLT FROM JAX TO DAY. ONCE IN THE DAY AIRSPACE, WE WERE CLRED FOR THE ILS APCH TO RWY 24R AND DOWN TO 3000 FT. 3000 FT WAS SET INTO THE ALT ALERT BY THE CAPT, AS THE FO WAS FLYING THE ACFT. DURING THE DSCNT, I WAS BUSY SCANNING THE ENGINEER PANEL AND SETTING UP THE ENG XFEED TO THE PROPER CONFIGN. LOOKING BACK FORWARD AT THE INSTS, I SAW THAT WE WERE PASSING THROUGH 2500 FT MSL. I THEN CHKED THE FO'S ALT INDICATOR AND SAW THAT WE WERE WELL BELOW GS. I WAS ABOUT TO INFORM THE FO OF THIS WHEN DAYTON TWR CALLED AND SAID HE WAS GETTING A LOW ALT ALERT AND THAT WE WERE TO CLB. THE CAPT REPLIED THAT WE WERE CORRECTING TO 2600 FT. THE FO THEN ACQUIRED THE GS, AND AN UNEVENTFUL LNDG ENSUED. THE WX WAS RPTED AS 210 DEGS/4 KTS, 5 MI MIST, 6 MI SCATTERED, 47 MI SCATTERED, 80 MI OVCST, 22/21/30.15. WE BROKE OUT OF THE CLOUD COVERAGE AND ACQUIRED THE RWY VISUALLY AT APPROX 1500 FT MSL AND 5 MI.

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.