Aircraft descends 1300 ft without clearance.

Attributes
ACN	278987
Time
Date	199408
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ipl
State Reference	CA
Altitude	msl bound lower : 3700 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air taxi
Make Model Name	Jetstream 31
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 250 flight time total : 9000 flight time type : 3500
ASRS Report	278987
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cleared to 7000 ft and reported the beacon (ipl) in sight. Cleared direct at 5000 ft. First officer was finally able to raise company on communication 2, while I listened in. Kept my eyes outside a lot as we were going into an uncontrolled field and overflying el centro NAS. Next thing we knew, center was calling and I saw that we were descending through 3700 ft. Told first officer to cancel the IFR and center said 'good night,' which it wasn't anymore! Considering all the effort my first officer and I put into attitude awareness, 'it' finally happened. Assessing the situation, I find that the tone of the altitude alerter is nearly inaudible in that I must turn down the audio panel volume to keep the new altitude alerter audio down to a reasonable level. Maybe if the 2 items were combined in one unit, the audio would be manageable! So much for technology. Never had an altitude bust before (last 6 yrs) with only the altitude alerter, but guess I won't fly into the ground at least! Callback conversation with reporter revealed the following information: captain was totally embarrassed over altitude deviation. There is no autoplt on this type of aircraft. It would have helped the flight crew greatly. Captain was positive this type of incident would never happen to him, he is now eating humble pie.

Original NASA ASRS Text

Title: ACFT DSNDS 1300 FT WITHOUT CLRNC.

Narrative: CLRED TO 7000 FT AND RPTED THE BEACON (IPL) IN SIGHT. CLRED DIRECT AT 5000 FT. FO WAS FINALLY ABLE TO RAISE COMPANY ON COM 2, WHILE I LISTENED IN. KEPT MY EYES OUTSIDE A LOT AS WE WERE GOING INTO AN UNCTLED FIELD AND OVERFLYING EL CENTRO NAS. NEXT THING WE KNEW, CTR WAS CALLING AND I SAW THAT WE WERE DSNDING THROUGH 3700 FT. TOLD FO TO CANCEL THE IFR AND CTR SAID 'GOOD NIGHT,' WHICH IT WASN'T ANYMORE! CONSIDERING ALL THE EFFORT MY FO AND I PUT INTO ATTITUDE AWARENESS, 'IT' FINALLY HAPPENED. ASSESSING THE SIT, I FIND THAT THE TONE OF THE ALT ALERTER IS NEARLY INAUDIBLE IN THAT I MUST TURN DOWN THE AUDIO PANEL VOLUME TO KEEP THE NEW ALT ALERTER AUDIO DOWN TO A REASONABLE LEVEL. MAYBE IF THE 2 ITEMS WERE COMBINED IN ONE UNIT, THE AUDIO WOULD BE MANAGEABLE! SO MUCH FOR TECHNOLOGY. NEVER HAD AN ALT BUST BEFORE (LAST 6 YRS) WITH ONLY THE ALT ALERTER, BUT GUESS I WON'T FLY INTO THE GND AT LEAST! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CAPT WAS TOTALLY EMBARRASSED OVER ALTDEV. THERE IS NO AUTOPLT ON THIS TYPE OF ACFT. IT WOULD HAVE HELPED THE FLC GREATLY. CAPT WAS POSITIVE THIS TYPE OF INCIDENT WOULD NEVER HAPPEN TO HIM, HE IS NOW EATING HUMBLE PIE.

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.