Narrative:

While en route IFR from oak to mhr operating under part 91 as aircraft X, I was beginning a final descent for the pilot navigation VOR/DME 22L. While on the feeder route between sacramento VOR and artey intersection, I received clearance to descend to 3000 ft, 500 ft below the 3500 ft MEA for that segment. Being familiar with receiving vectors to final approach that frequently took one in under the GS intercept altitude for an ILS, I was not entirely unused to a situation where one is brought in for approach in a manner slightly different from what is depicted on the approach chart. After being told to 'cross artey at 3000 ft, cleared VOR/DME 22L,' my suspicions began to grow as I wondered how I could comply with a procedure that called for an MDA of 3500 ft throughout course reversal. In the 2-3 mins that elapsed between accepting this clearance until I positioned the aircraft so as to comply with the procedure (upon being established inbound), I wondered if I had been in compliance, but did not question ATC's clearance due to a number of factors including the fact that I was in VMC and suspected the controller knew this (he wanted to assign me the visual approach but I specifically asked for the VOR/DME), and thought this might be a local standard procedure. Not until later in the day when I returned to oak and posed this question to fellow flight instructors did I begin to suspect the controller may have been in error. To a person, all were confused though most assumed this was just a case similar to being vectored onto final, but the question remained: how could one comply with a procedure when they were already below its MDA for that segment? Further, how could one be assured of obstacle clearance when below these altitudes while conducting the approach pilot navigation? The question was finally resolved by calling sacramento approach by telephone and presenting the situation, and asking for clarification. The controller there stated that it sounded like my controller had indeed made a mistake in issuing that altitude. Upon furnishing my call sign, time of approach, and assuring the controller that I wanted no further action to be taken, only clarification of how to comply, did I realize my own error in not questioning the clearance at first issuance, and my own responsibility for accepting it in violation of charted procedure. Sac approach said they would investigate the case in the hope of improving safety, and that no action would be taken. If asked to speculate on the cause of the problem my answer would be twofold: first, the controller's mistake in issuing a faulty descent that brought me in below MDA. Secondly, and ultimately, the responsibility for continued descent and approach below specified minimums lies with me in my acceptance of a faulty clearance without question, perhaps due to my practical unfamiliarity with the IFR system, and then perhaps due the attitude many pilots have while under IFR that controllers must have a reason for what they issue so it is best not to tie up the frequency asking for clarification or explanation. When issued the clearance, it was read back, confirmed, and that was enough for me. I believe that this was a case where my normal sharp judgement was allowed to relax as I was 'controled' rather than take full responsibility for my flight's direction and outcome. Thankfully the deviation was minor and in VMC. I know personally that prevention of this type of mistake in the future will come in my increased criticism of each controller's clearance (especially on approach, close to terrain), and a conscious effort not to react in a somewhat passive manner while under IFR.

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Original NASA ASRS Text

Title: A C172 PLT RECEIVED AND COMPLIED WITH A FAULTY CLRNC FROM ATC ON APCH TO MHR.

Narrative: WHILE ENRTE IFR FROM OAK TO MHR OPERATING UNDER PART 91 AS ACFT X, I WAS BEGINNING A FINAL DSCNT FOR THE PLT NAV VOR/DME 22L. WHILE ON THE FEEDER RTE BTWN SACRAMENTO VOR AND ARTEY INTXN, I RECEIVED CLRNC TO DSND TO 3000 FT, 500 FT BELOW THE 3500 FT MEA FOR THAT SEGMENT. BEING FAMILIAR WITH RECEIVING VECTORS TO FINAL APCH THAT FREQUENTLY TOOK ONE IN UNDER THE GS INTERCEPT ALT FOR AN ILS, I WAS NOT ENTIRELY UNUSED TO A SIT WHERE ONE IS BROUGHT IN FOR APCH IN A MANNER SLIGHTLY DIFFERENT FROM WHAT IS DEPICTED ON THE APCH CHART. AFTER BEING TOLD TO 'CROSS ARTEY AT 3000 FT, CLRED VOR/DME 22L,' MY SUSPICIONS BEGAN TO GROW AS I WONDERED HOW I COULD COMPLY WITH A PROC THAT CALLED FOR AN MDA OF 3500 FT THROUGHOUT COURSE REVERSAL. IN THE 2-3 MINS THAT ELAPSED BTWN ACCEPTING THIS CLRNC UNTIL I POSITIONED THE ACFT SO AS TO COMPLY WITH THE PROC (UPON BEING ESTABLISHED INBOUND), I WONDERED IF I HAD BEEN IN COMPLIANCE, BUT DID NOT QUESTION ATC'S CLRNC DUE TO A NUMBER OF FACTORS INCLUDING THE FACT THAT I WAS IN VMC AND SUSPECTED THE CTLR KNEW THIS (HE WANTED TO ASSIGN ME THE VISUAL APCH BUT I SPECIFICALLY ASKED FOR THE VOR/DME), AND THOUGHT THIS MIGHT BE A LCL STANDARD PROC. NOT UNTIL LATER IN THE DAY WHEN I RETURNED TO OAK AND POSED THIS QUESTION TO FELLOW FLT INSTRUCTORS DID I BEGIN TO SUSPECT THE CTLR MAY HAVE BEEN IN ERROR. TO A PERSON, ALL WERE CONFUSED THOUGH MOST ASSUMED THIS WAS JUST A CASE SIMILAR TO BEING VECTORED ONTO FINAL, BUT THE QUESTION REMAINED: HOW COULD ONE COMPLY WITH A PROC WHEN THEY WERE ALREADY BELOW ITS MDA FOR THAT SEGMENT? FURTHER, HOW COULD ONE BE ASSURED OF OBSTACLE CLRNC WHEN BELOW THESE ALTS WHILE CONDUCTING THE APCH PLT NAV? THE QUESTION WAS FINALLY RESOLVED BY CALLING SACRAMENTO APCH BY TELEPHONE AND PRESENTING THE SIT, AND ASKING FOR CLARIFICATION. THE CTLR THERE STATED THAT IT SOUNDED LIKE MY CTLR HAD INDEED MADE A MISTAKE IN ISSUING THAT ALT. UPON FURNISHING MY CALL SIGN, TIME OF APCH, AND ASSURING THE CTLR THAT I WANTED NO FURTHER ACTION TO BE TAKEN, ONLY CLARIFICATION OF HOW TO COMPLY, DID I REALIZE MY OWN ERROR IN NOT QUESTIONING THE CLRNC AT FIRST ISSUANCE, AND MY OWN RESPONSIBILITY FOR ACCEPTING IT IN VIOLATION OF CHARTED PROC. SAC APCH SAID THEY WOULD INVESTIGATE THE CASE IN THE HOPE OF IMPROVING SAFETY, AND THAT NO ACTION WOULD BE TAKEN. IF ASKED TO SPECULATE ON THE CAUSE OF THE PROB MY ANSWER WOULD BE TWOFOLD: FIRST, THE CTLR'S MISTAKE IN ISSUING A FAULTY DSCNT THAT BROUGHT ME IN BELOW MDA. SECONDLY, AND ULTIMATELY, THE RESPONSIBILITY FOR CONTINUED DSCNT AND APCH BELOW SPECIFIED MINIMUMS LIES WITH ME IN MY ACCEPTANCE OF A FAULTY CLRNC WITHOUT QUESTION, PERHAPS DUE TO MY PRACTICAL UNFAMILIARITY WITH THE IFR SYS, AND THEN PERHAPS DUE THE ATTITUDE MANY PLTS HAVE WHILE UNDER IFR THAT CTLRS MUST HAVE A REASON FOR WHAT THEY ISSUE SO IT IS BEST NOT TO TIE UP THE FREQ ASKING FOR CLARIFICATION OR EXPLANATION. WHEN ISSUED THE CLRNC, IT WAS READ BACK, CONFIRMED, AND THAT WAS ENOUGH FOR ME. I BELIEVE THAT THIS WAS A CASE WHERE MY NORMAL SHARP JUDGEMENT WAS ALLOWED TO RELAX AS I WAS 'CTLED' RATHER THAN TAKE FULL RESPONSIBILITY FOR MY FLT'S DIRECTION AND OUTCOME. THANKFULLY THE DEV WAS MINOR AND IN VMC. I KNOW PERSONALLY THAT PREVENTION OF THIS TYPE OF MISTAKE IN THE FUTURE WILL COME IN MY INCREASED CRITICISM OF EACH CTLR'S CLRNC (ESPECIALLY ON APCH, CLOSE TO TERRAIN), AND A CONSCIOUS EFFORT NOT TO REACT IN A SOMEWHAT PASSIVE MANNER WHILE UNDER IFR.

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.