ATC gave corp jet an incorrect altimeter setting which could have led to CFIT.

Attributes
ACN	175719
Time
Date	199104
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : stk
State Reference	CO
Altitude	msl bound lower : 17000 msl bound upper : 21000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 12700 flight time type : 500
ASRS Report	175719
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	faa : investigated faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Level at FL210, requested descent. Cleared to 17000' MSL and given ako WX and altimeter of 3017. We have a global afis and we were looking at current ako and sny sa altimeter was 2952, not 3017. Altimeter at cys on departure was 29.57. We knew that ATC had given us the wrong altimeter setting. I was about to ask them when ATC handed us off to the next sector (125.95). After reporting on the new controller, I asked him to verify the altimeter given to us by the previous controller of 30.17. The new controller said the 30.17 was in error, the correct ako altimeter was 29.52. The controller went right on with no further mention of this error of 650'. The WX at destination (stk) caused us to request clearance for the INS approach into stk (NDB runway 33). Airport elevation is 4038'. MDA with ako altimeter is 4560' MSL (427' haa). If a pilot took ATC's word as always correct and could not get the local altimeter from unicom, and the local WX had low ceiling/visibility, the pilot could hit the ground and the altimeter would indicated an altitude above MDA. I called ATC supervisor and explained the problem. The controller (125.95) didn't seem concerned. The supervisor understood the potential major problem that could happen, and said he would pull the tape. Communication problem. ATC controllers need to understand what this type of error could cause.

Original NASA ASRS Text

Title: ATC GAVE CORP JET AN INCORRECT ALTIMETER SETTING WHICH COULD HAVE LED TO CFIT.

Narrative: LEVEL AT FL210, REQUESTED DSNT. CLRED TO 17000' MSL AND GIVEN AKO WX AND ALTIMETER OF 3017. WE HAVE A GLOBAL AFIS AND WE WERE LOOKING AT CURRENT AKO AND SNY SA ALTIMETER WAS 2952, NOT 3017. ALTIMETER AT CYS ON DEP WAS 29.57. WE KNEW THAT ATC HAD GIVEN US THE WRONG ALTIMETER SETTING. I WAS ABOUT TO ASK THEM WHEN ATC HANDED US OFF TO THE NEXT SECTOR (125.95). AFTER RPTING ON THE NEW CTLR, I ASKED HIM TO VERIFY THE ALTIMETER GIVEN TO US BY THE PREVIOUS CTLR OF 30.17. THE NEW CTLR SAID THE 30.17 WAS IN ERROR, THE CORRECT AKO ALTIMETER WAS 29.52. THE CTLR WENT RIGHT ON WITH NO FURTHER MENTION OF THIS ERROR OF 650'. THE WX AT DEST (STK) CAUSED US TO REQUEST CLRNC FOR THE INS APCH INTO STK (NDB RWY 33). ARPT ELEVATION IS 4038'. MDA WITH AKO ALTIMETER IS 4560' MSL (427' HAA). IF A PLT TOOK ATC'S WORD AS ALWAYS CORRECT AND COULD NOT GET THE LCL ALTIMETER FROM UNICOM, AND THE LCL WX HAD LOW CEILING/VISIBILITY, THE PLT COULD HIT THE GND AND THE ALTIMETER WOULD INDICATED AN ALT ABOVE MDA. I CALLED ATC SUPVR AND EXPLAINED THE PROB. THE CTLR (125.95) DIDN'T SEEM CONCERNED. THE SUPVR UNDERSTOOD THE POTENTIAL MAJOR PROB THAT COULD HAPPEN, AND SAID HE WOULD PULL THE TAPE. COM PROB. ATC CTLRS NEED TO UNDERSTAND WHAT THIS TYPE OF ERROR COULD CAUSE.

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.