Narrative:

Our aircraft, a (type) call sign medium large transport X, was on an IFR flight plan from washington, dc, nat'l airport to monterey peninsula airport, ca. Descending into the monterey area we were placed on radar vectors by oakland center and then handed off to monterey approach control at approximately 20 mi from the destination airport. Monterey approach advised us of our position (approximately 19 mi northeast of the airport), that we were being vectored for a visual approach to runway 28L at monterey, and requested us to report the airport in sight. Monterey approach control instructed us to descend to 6000', and then to 5000'. The WX was perfect (sky clear and visibility greater than 10 mi) and there were no other aircraft reported in the area at the time. We saw salinas municipal airport at approximately the same time as making initial contact with approach control. Soon thereafter we spotted monterey airport. However, since neither of us had ever flown into that area before, I did not immediately advise the approach controller that we had monterey airport in sight. Next, the approach controller advised that our position was 11 mi from the airport, which was in our 1 O'clock position. I replied that we thought we had the right airport in sight but had delayed reporting it until we were certain. The controller responded with a simple 'roger'. Several seconds later I reported that we had the airport in sight. At that time the controller cleared us for a visual approach. We continued the approach to an uneventful landing. The following morning, july xx, 1989, I received a telephone call from the monterey air traffic facility manager informing me that he would be processing a report of pilot violation against the pilot of medium large transport X. This was the first indication we had that a violation had occurred and came as quite a surprise. The other pilot and I immediately visited with the manager at the tower to listen to a replay of the ATC tape and to discuss the situation (see copy of incident report attached). I was shocked that we might have possibly descended 800' below our assigned altitude. We were neither aware of, nor would we have intentionally allowed, such a situation to occur. However, I was also disturbed by the fact that the controller would watch this event happening and discuss our lower-than-authorized altitude (as observed on the radar) with his supervisor rather than immediately advising the aircraft of the observed deviation as required by the FAA operations and maintenance handbook 7210.3I, paragraph 506. We asked the manager why the controller failed to advise us of the apparent deviation, either in time to make a correction in altitude or even to let us know in a timely manner that a deviation had occurred. The manager stated that, during a discussion of the events (subsequent to our landing), the controllers expressed a reluctance to say anything to us over the radio because they didn't know who else might be listening, including our passenger, secretary of transportation. The controllers also speculated that, since WX and traffic were not a factor, perhaps our vertical profile was deliberate in order to test their reactions. Had this been a test (for which there is no precedent) the controllers would have been quickly critiqued on their failure to advise us in a timely manner of our apparent altitude deviation.

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Original NASA ASRS Text

Title: MLG DESCENDED BELOW LAST ASSIGNED ALT WITHOUT AUTHORIZATION.

Narrative: OUR ACFT, A (TYPE) CALL SIGN MLG X, WAS ON AN IFR FLT PLAN FROM WASHINGTON, DC, NAT'L ARPT TO MONTEREY PENINSULA ARPT, CA. DESCENDING INTO THE MONTEREY AREA WE WERE PLACED ON RADAR VECTORS BY OAKLAND CENTER AND THEN HANDED OFF TO MONTEREY APCH CTL AT APPROX 20 MI FROM THE DEST ARPT. MONTEREY APCH ADVISED US OF OUR POSITION (APPROX 19 MI NE OF THE ARPT), THAT WE WERE BEING VECTORED FOR A VISUAL APCH TO RWY 28L AT MONTEREY, AND REQUESTED US TO REPORT THE ARPT IN SIGHT. MONTEREY APCH CTL INSTRUCTED US TO DSND TO 6000', AND THEN TO 5000'. THE WX WAS PERFECT (SKY CLEAR AND VISIBILITY GREATER THAN 10 MI) AND THERE WERE NO OTHER ACFT REPORTED IN THE AREA AT THE TIME. WE SAW SALINAS MUNI ARPT AT APPROX THE SAME TIME AS MAKING INITIAL CONTACT WITH APCH CTL. SOON THEREAFTER WE SPOTTED MONTEREY ARPT. HOWEVER, SINCE NEITHER OF US HAD EVER FLOWN INTO THAT AREA BEFORE, I DID NOT IMMEDIATELY ADVISE THE APCH CTLR THAT WE HAD MONTEREY ARPT IN SIGHT. NEXT, THE APCH CTLR ADVISED THAT OUR POSITION WAS 11 MI FROM THE ARPT, WHICH WAS IN OUR 1 O'CLOCK POSITION. I REPLIED THAT WE THOUGHT WE HAD THE RIGHT ARPT IN SIGHT BUT HAD DELAYED REPORTING IT UNTIL WE WERE CERTAIN. THE CTLR RESPONDED WITH A SIMPLE 'ROGER'. SEVERAL SECONDS LATER I REPORTED THAT WE HAD THE ARPT IN SIGHT. AT THAT TIME THE CTLR CLRED US FOR A VISUAL APCH. WE CONTINUED THE APCH TO AN UNEVENTFUL LNDG. THE FOLLOWING MORNING, JULY XX, 1989, I RECEIVED A TELEPHONE CALL FROM THE MONTEREY AIR TFC FAC MGR INFORMING ME THAT HE WOULD BE PROCESSING A REPORT OF PLT VIOLATION AGAINST THE PLT OF MLG X. THIS WAS THE FIRST INDICATION WE HAD THAT A VIOLATION HAD OCCURRED AND CAME AS QUITE A SURPRISE. THE OTHER PLT AND I IMMEDIATELY VISITED WITH THE MGR AT THE TWR TO LISTEN TO A REPLAY OF THE ATC TAPE AND TO DISCUSS THE SITUATION (SEE COPY OF INCIDENT REPORT ATTACHED). I WAS SHOCKED THAT WE MIGHT HAVE POSSIBLY DESCENDED 800' BELOW OUR ASSIGNED ALT. WE WERE NEITHER AWARE OF, NOR WOULD WE HAVE INTENTIONALLY ALLOWED, SUCH A SITUATION TO OCCUR. HOWEVER, I WAS ALSO DISTURBED BY THE FACT THAT THE CTLR WOULD WATCH THIS EVENT HAPPENING AND DISCUSS OUR LOWER-THAN-AUTHORIZED ALT (AS OBSERVED ON THE RADAR) WITH HIS SUPVR RATHER THAN IMMEDIATELY ADVISING THE ACFT OF THE OBSERVED DEVIATION AS REQUIRED BY THE FAA OPERATIONS AND MAINT HANDBOOK 7210.3I, PARAGRAPH 506. WE ASKED THE MGR WHY THE CTLR FAILED TO ADVISE US OF THE APPARENT DEVIATION, EITHER IN TIME TO MAKE A CORRECTION IN ALT OR EVEN TO LET US KNOW IN A TIMELY MANNER THAT A DEVIATION HAD OCCURRED. THE MGR STATED THAT, DURING A DISCUSSION OF THE EVENTS (SUBSEQUENT TO OUR LNDG), THE CTLRS EXPRESSED A RELUCTANCE TO SAY ANYTHING TO US OVER THE RADIO BECAUSE THEY DIDN'T KNOW WHO ELSE MIGHT BE LISTENING, INCLUDING OUR PAX, SECRETARY OF TRANSPORTATION. THE CTLRS ALSO SPECULATED THAT, SINCE WX AND TFC WERE NOT A FACTOR, PERHAPS OUR VERTICAL PROFILE WAS DELIBERATE IN ORDER TO TEST THEIR REACTIONS. HAD THIS BEEN A TEST (FOR WHICH THERE IS NO PRECEDENT) THE CTLRS WOULD HAVE BEEN QUICKLY CRITIQUED ON THEIR FAILURE TO ADVISE US IN A TIMELY MANNER OF OUR APPARENT ALT DEVIATION.

Data retrieved from NASA's ASRS site as of August 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.