Narrative:

On our flight from lga to bos just after departure, we had a change of route from the norwich 2 arrival to the suupp 2 arrival. At armun intersection we received vectors for the ILS runway 27 at bos. We had various altitude and heading changes for approximately 20 mins. We were given a descent to 6000 ft and when we were leveling at 6000 ft approach advised us of a change of runway and to expect vectors to the ILS runway 4R approach at bos. I pulled out the approach plate for ILS runway 4R and briefed the first officer on the important changes to the approach and the first officer was setting the instruments as I briefed. After the briefing, I noticed we were descending to 5700 ft and called out the deviation. The first officer then added power and climbed back to the assigned altitude of 6000 ft. The first officer couldn't recall if he engaged the altitude hold at 6000 ft or it failed to engage. The so prior to 6000 ft was told to brief the passenger on the extensive delay and was doing so at the time of the deviation. (Note: there was no conflict with any other aircraft.) the crew suggests that the block iv autoplt installed on the B727 should have an altitude hold light indicating when the altitude hold feature is engaged, so all the crew members can easily see when it is engaged. The altitude hold switch is on the center pedestal and at night can be difficult to see its position.

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Original NASA ASRS Text

Title: B727 CREW INBOUND TO BOS WERE APCHING 6000 FT WHEN APCH CTL ADVISED A CHANGE IN RWYS AND APCH PROC. CREW WAS DISTR SETTING EQUIP UP FOR THE NEW APCH AND OVERSHOT THEIR ALT.

Narrative: ON OUR FLT FROM LGA TO BOS JUST AFTER DEP, WE HAD A CHANGE OF RTE FROM THE NORWICH 2 ARR TO THE SUUPP 2 ARR. AT ARMUN INTXN WE RECEIVED VECTORS FOR THE ILS RWY 27 AT BOS. WE HAD VARIOUS ALT AND HDG CHANGES FOR APPROX 20 MINS. WE WERE GIVEN A DSCNT TO 6000 FT AND WHEN WE WERE LEVELING AT 6000 FT APCH ADVISED US OF A CHANGE OF RWY AND TO EXPECT VECTORS TO THE ILS RWY 4R APCH AT BOS. I PULLED OUT THE APCH PLATE FOR ILS RWY 4R AND BRIEFED THE FO ON THE IMPORTANT CHANGES TO THE APCH AND THE FO WAS SETTING THE INSTS AS I BRIEFED. AFTER THE BRIEFING, I NOTICED WE WERE DSNDING TO 5700 FT AND CALLED OUT THE DEV. THE FO THEN ADDED PWR AND CLBED BACK TO THE ASSIGNED ALT OF 6000 FT. THE FO COULDN'T RECALL IF HE ENGAGED THE ALT HOLD AT 6000 FT OR IT FAILED TO ENGAGE. THE SO PRIOR TO 6000 FT WAS TOLD TO BRIEF THE PAX ON THE EXTENSIVE DELAY AND WAS DOING SO AT THE TIME OF THE DEV. (NOTE: THERE WAS NO CONFLICT WITH ANY OTHER ACFT.) THE CREW SUGGESTS THAT THE BLOCK IV AUTOPLT INSTALLED ON THE B727 SHOULD HAVE AN ALT HOLD LIGHT INDICATING WHEN THE ALT HOLD FEATURE IS ENGAGED, SO ALL THE CREW MEMBERS CAN EASILY SEE WHEN IT IS ENGAGED. THE ALT HOLD SWITCH IS ON THE CTR PEDESTAL AND AT NIGHT CAN BE DIFFICULT TO SEE ITS POS.

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.