B737-300 flight crew were issued low altitude alert by approach controller wherein the flight crew w...

Attributes
ACN	559480
Time
Date	200209
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : san.airport
State Reference	CA
Altitude	msl bound lower : 3300 msl bound upper : 3600
Environment
Flight Conditions	Mixed
Weather Elements	other
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sct.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer only : 27
Flight Phase	descent : approach
Route In Use	approach : instrument non precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : multi engine pilot : cfi
Experience	flight time last 90 days : 240 flight time total : 6500 flight time type : 4000
ASRS Report	559480
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	non adherence : published procedure other spatial deviation
Independent Detector	atc equipment : msaw other controllera
Resolutory Action	controller : issued alert flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Airspace Structure Aircraft
Primary Problem	Aircraft

Narrative:

We experienced a normal descent and were 'cleared for the localizer runway 27 approach, san diego, 4000 ft until established, 'and once intercepting the localizer course, descend to the published altitude of 3600 ft.' just prior to reaching swatt intersection, socal approach came on frequency asking us to 'stop our descent' as they were receiving a 300 ft low altitude (GPWS) warning alert on our aircraft. We replied that we were sorry, but that we were showing 3600 ft and had not yet begun descending to our next step-down altitude. We held this altitude until well past swatt to ensure no conflict, and approximately 1/2 mi after swatt, began our descent to the next altitude before our FAF, 2000 ft. My first officer and I were both very surprised by this series of confusing perceptions on the part of ATC. We were not in any conflict with terrain (this portion of our approach was totally visual -- only later did we encounter a marine layer of clouds on the approach to san) or other aircraft. We felt this controller's continued verbal challenges about our altitude constituted a distraction during a busy portion of our localizer approach. I don't know if this controller was receiving a faulty mode C transponder return from us, or if it was his ground radar painting us 'low,' but it sure grabbed our attention. One would think that if we were truly '300 ft low' from our assigned/published legal altitude, he might have issued immediate instructions for a climbing vector away from terrain. In any case, we were glad to avoid any conflict with terrain, and the remainder of our localizer approach and landing at san diego was uneventful. This controller seemed 'edgy' and tense with several aircraft. It appeared to us almost as though he was 'punishing' us for persistently requesting lower during our earlier phases of the descent. This is probably not the case, but the controller did seem quite pressured by the numerous GA aircraft he was handling, all of which were encountering low IFR minimums at their intended airports and many of whom spoke very broken english.

Original NASA ASRS Text

Title: B737-300 FLC WERE ISSUED LOW ALT ALERT BY APCH CTLR WHEREIN THE FLC WERE AMAZED SINCE THEIR ALTIMETERS CONFIRMED THAT THEY WERE MAINTAINING THE PUBLISHED ALT.

Narrative: WE EXPERIENCED A NORMAL DSCNT AND WERE 'CLRED FOR THE LOC RWY 27 APCH, SAN DIEGO, 4000 FT UNTIL ESTABLISHED, 'AND ONCE INTERCEPTING THE LOC COURSE, DSND TO THE PUBLISHED ALT OF 3600 FT.' JUST PRIOR TO REACHING SWATT INTXN, SOCAL APCH CAME ON FREQ ASKING US TO 'STOP OUR DSCNT' AS THEY WERE RECEIVING A 300 FT LOW ALT (GPWS) WARNING ALERT ON OUR ACFT. WE REPLIED THAT WE WERE SORRY, BUT THAT WE WERE SHOWING 3600 FT AND HAD NOT YET BEGUN DSNDING TO OUR NEXT STEP-DOWN ALT. WE HELD THIS ALT UNTIL WELL PAST SWATT TO ENSURE NO CONFLICT, AND APPROX 1/2 MI AFTER SWATT, BEGAN OUR DSCNT TO THE NEXT ALT BEFORE OUR FAF, 2000 FT. MY FO AND I WERE BOTH VERY SURPRISED BY THIS SERIES OF CONFUSING PERCEPTIONS ON THE PART OF ATC. WE WERE NOT IN ANY CONFLICT WITH TERRAIN (THIS PORTION OF OUR APCH WAS TOTALLY VISUAL -- ONLY LATER DID WE ENCOUNTER A MARINE LAYER OF CLOUDS ON THE APCH TO SAN) OR OTHER ACFT. WE FELT THIS CTLR'S CONTINUED VERBAL CHALLENGES ABOUT OUR ALT CONSTITUTED A DISTR DURING A BUSY PORTION OF OUR LOC APCH. I DON'T KNOW IF THIS CTLR WAS RECEIVING A FAULTY MODE C XPONDER RETURN FROM US, OR IF IT WAS HIS GND RADAR PAINTING US 'LOW,' BUT IT SURE GRABBED OUR ATTN. ONE WOULD THINK THAT IF WE WERE TRULY '300 FT LOW' FROM OUR ASSIGNED/PUBLISHED LEGAL ALT, HE MIGHT HAVE ISSUED IMMEDIATE INSTRUCTIONS FOR A CLBING VECTOR AWAY FROM TERRAIN. IN ANY CASE, WE WERE GLAD TO AVOID ANY CONFLICT WITH TERRAIN, AND THE REMAINDER OF OUR LOC APCH AND LNDG AT SAN DIEGO WAS UNEVENTFUL. THIS CTLR SEEMED 'EDGY' AND TENSE WITH SEVERAL ACFT. IT APPEARED TO US ALMOST AS THOUGH HE WAS 'PUNISHING' US FOR PERSISTENTLY REQUESTING LOWER DURING OUR EARLIER PHASES OF THE DSCNT. THIS IS PROBABLY NOT THE CASE, BUT THE CTLR DID SEEM QUITE PRESSURED BY THE NUMEROUS GA ACFT HE WAS HANDLING, ALL OF WHICH WERE ENCOUNTERING LOW IFR MINIMUMS AT THEIR INTENDED ARPTS AND MANY OF WHOM SPOKE VERY BROKEN ENGLISH.

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.

B737-300 flight crew were issued low altitude alert by approach controller wherein the flight crew were amazed since their altimeters confirmed that they were maintaining the published altitude.