Corp helicopter descends abruptly to MDA, causes low altitude alert.

Attributes
ACN	243021
Time
Date	199306
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mmu
State Reference	NJ
Altitude	msl bound lower : 870 msl bound upper : 870
Environment
Flight Conditions	Mixed
Light	Dusk
Aircraft 1
Controlling Facilities	tower : mmu
Operator	general aviation : corporate
Make Model Name	Helicopter
Flight Phase	descent : approach
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 70 flight time total : 9500 flight time type : 3000
ASRS Report	243021
Person 2
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure other spatial deviation
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft was cleared by ny approach control for an NDB runway 5 to mmu, nj, and we were turned over to mmu tower outside of the NDB. After crossing the NDB inbound, we immediately descended to our MDA and slowed the aircraft. Being a helicopter, this is easily accomplished. Mmu tower informed us that ny approach told the tower of a low altitude alert. We informed him we were already at MDA and proceeding inbound. At this time we had ground contact and were looking for the airport. A normal landing followed.

Original NASA ASRS Text

Title: CORP HELI DSNDS ABRUPTLY TO MDA, CAUSES LOW ALT ALERT.

Narrative: ACFT WAS CLRED BY NY APCH CTL FOR AN NDB RWY 5 TO MMU, NJ, AND WE WERE TURNED OVER TO MMU TWR OUTSIDE OF THE NDB. AFTER XING THE NDB INBOUND, WE IMMEDIATELY DSNDED TO OUR MDA AND SLOWED THE ACFT. BEING A HELI, THIS IS EASILY ACCOMPLISHED. MMU TWR INFORMED US THAT NY APCH TOLD THE TWR OF A LOW ALT ALERT. WE INFORMED HIM WE WERE ALREADY AT MDA AND PROCEEDING INBOUND. AT THIS TIME WE HAD GND CONTACT AND WERE LOOKING FOR THE ARPT. A NORMAL LNDG FOLLOWED.

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.