Air carrier X had near midair collision with aircraft. Y. See and avoid concept.

Attributes
ACN	206168
Time
Date	199203
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : fdk
State Reference	ND
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad artcc : zlc
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	approach : visual
Flight Plan	None
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 7 controller radar : 3
ASRS Report	206168
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Miss Distance	horizontal : 0 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Air carrier X reported a near miss with a VFR aircraft Y. Air carrier X was being vectored for a downwind for runway 14 at iad. There were approximately 20 VFR aircraft 3000 ft and below within a 5 mi radius of fdk airport. Aircraft Y was observed after the report to have an intermittent mode C of 5100 ft. It was the first nice VFR sunday. The vfrs were out in force. After this occurrence, I called different traffic to another commuter pilot. This traffic was level at 5000 ft VFR. An additional traffic call about 45 seconds later on another aircraft level at 5000 ft VFR. Whatever happened to VFR cardinal altitudes? I believe that these VFR aircraft were trying to get above mountain wave turbulence. Numerous aircraft reported rides smoothing out above 5000 ft.

Original NASA ASRS Text

Title: ACR X HAD NMAC WITH ACFT. Y. SEE AND AVOID CONCEPT.

Narrative: ACR X RPTED A NEAR MISS WITH A VFR ACFT Y. ACR X WAS BEING VECTORED FOR A DOWNWIND FOR RWY 14 AT IAD. THERE WERE APPROX 20 VFR ACFT 3000 FT AND BELOW WITHIN A 5 MI RADIUS OF FDK ARPT. ACFT Y WAS OBSERVED AFTER THE RPT TO HAVE AN INTERMITTENT MODE C OF 5100 FT. IT WAS THE FIRST NICE VFR SUNDAY. THE VFRS WERE OUT IN FORCE. AFTER THIS OCCURRENCE, I CALLED DIFFERENT TFC TO ANOTHER COMMUTER PLT. THIS TFC WAS LEVEL AT 5000 FT VFR. AN ADDITIONAL TFC CALL ABOUT 45 SECONDS LATER ON ANOTHER ACFT LEVEL AT 5000 FT VFR. WHATEVER HAPPENED TO VFR CARDINAL ALTS? I BELIEVE THAT THESE VFR ACFT WERE TRYING TO GET ABOVE MOUNTAIN WAVE TURB. NUMEROUS ACFT RPTED RIDES SMOOTHING OUT ABOVE 5000 FT.

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.