Close proximity GA-small aircraft air carrier-commuter mdt at the base of den TCA.

Attributes
ACN	94102
Time
Date	198809
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : den
State Reference	CO
Altitude	msl bound lower : 7100 msl bound upper : 7500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : den
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Flight Plan	None
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Transport
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Experience	flight time last 90 days : 22 flight time total : 300
ASRS Report	94102
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : nmac
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 400
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

I was flying 1 passenger (an instrument rated private pilot) at 7300 MSL under the 8000 floor of the denver TCA. An air carrier airways mdtg was several mi to our west and above us. After scanning for other traffic, checking radios, DME and charts, I looked again for the mdt to find him approximately 1 mi and almost at our altitude. Contacted den approach, was told the mdt was cleared to 7500 and that we had not been called as traffic to the mdt because the controller was 'too busy.' mdt passed above us (we dove to 7100). Controller sounded 'rattled.' question. Why, when the mdt was approaching stapleton from the west (which means he must have been at 13000 or higher over the mountains), was he being brought into the TCA under the floor of an outer layer, near a busy GA airport (bjc, jefferson county)? If it was an error by an inexperienced controller, I can understand if, but it that is to be a standard ATC practice, then it is a very stupid one. Also, how did our mode C increase the safety of our flight?

Original NASA ASRS Text

Title: CLOSE PROX GA-SMA ACR-COMMUTER MDT AT THE BASE OF DEN TCA.

Narrative: I WAS FLYING 1 PAX (AN INSTRUMENT RATED PRIVATE PLT) AT 7300 MSL UNDER THE 8000 FLOOR OF THE DENVER TCA. AN ACR AIRWAYS MDTG WAS SEVERAL MI TO OUR W AND ABOVE US. AFTER SCANNING FOR OTHER TFC, CHKING RADIOS, DME AND CHARTS, I LOOKED AGAIN FOR THE MDT TO FIND HIM APPROX 1 MI AND ALMOST AT OUR ALT. CONTACTED DEN APCH, WAS TOLD THE MDT WAS CLRED TO 7500 AND THAT WE HAD NOT BEEN CALLED AS TFC TO THE MDT BECAUSE THE CTLR WAS 'TOO BUSY.' MDT PASSED ABOVE US (WE DOVE TO 7100). CTLR SOUNDED 'RATTLED.' QUESTION. WHY, WHEN THE MDT WAS APCHING STAPLETON FROM THE W (WHICH MEANS HE MUST HAVE BEEN AT 13000 OR HIGHER OVER THE MOUNTAINS), WAS HE BEING BROUGHT INTO THE TCA UNDER THE FLOOR OF AN OUTER LAYER, NEAR A BUSY GA ARPT (BJC, JEFFERSON COUNTY)? IF IT WAS AN ERROR BY AN INEXPERIENCED CTLR, I CAN UNDERSTAND IF, BUT IT THAT IS TO BE A STANDARD ATC PRACTICE, THEN IT IS A VERY STUPID ONE. ALSO, HOW DID OUR MODE C INCREASE THE SAFETY OF OUR FLT?

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.