Controller claims that aircraft at low altitudes will drop data tag or not display a beacon.

Attributes
ACN	256697
Time
Date	199311
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : stl airport : sus
State Reference	MO
Altitude	msl bound lower : 3000 msl bound upper : 7500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : stl
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Route In Use	enroute airway : stl
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 3
ASRS Report	256697
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

In a 1 hour period I worked 3 IFR and 1 VFR aircraft that did not display a beacon or data tag. Small transport X no primary from 50 to 40 mi southwest of stl and no beacon from 50 to 20 southwest of stl landing 3WE IFR. Small transport Y no beacon from 50 mi southwest to 35 mi southwest of stl landing stl IFR. Small aircraft Z no primary 50 northeast to 35 northeast landing sus IFR. Small transport a VFR toy VOR to 40 northeast, no beacon from 3000 to 7500. Callback conversation with reporter revealed the following information: reporter states that most aircraft are at or below 5000 ft. Aircraft will tag up and after a few sweeps, will drop off. This was an intermittent problem, however, it is not doing it now. These low aircraft cannot be issued a higher altitude because of other IFR traffic above. Analyst stated to the reporter that some of the distances involved might be too far for the radar to pick aircraft up, especially at the lower altitudes. Reporter indicated that other reports would be sent to ASRS if the conditions occur again.

Original NASA ASRS Text

Title: CTLR CLAIMS THAT ACFT AT LOW ALTS WILL DROP DATA TAG OR NOT DISPLAY A BEACON.

Narrative: IN A 1 HR PERIOD I WORKED 3 IFR AND 1 VFR ACFT THAT DID NOT DISPLAY A BEACON OR DATA TAG. SMT X NO PRIMARY FROM 50 TO 40 MI SW OF STL AND NO BEACON FROM 50 TO 20 SW OF STL LNDG 3WE IFR. SMT Y NO BEACON FROM 50 MI SW TO 35 MI SW OF STL LNDG STL IFR. SMA Z NO PRIMARY 50 NE TO 35 NE LNDG SUS IFR. SMT A VFR TOY VOR TO 40 NE, NO BEACON FROM 3000 TO 7500. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT MOST ACFT ARE AT OR BELOW 5000 FT. ACFT WILL TAG UP AND AFTER A FEW SWEEPS, WILL DROP OFF. THIS WAS AN INTERMITTENT PROB, HOWEVER, IT IS NOT DOING IT NOW. THESE LOW ACFT CANNOT BE ISSUED A HIGHER ALT BECAUSE OF OTHER IFR TFC ABOVE. ANALYST STATED TO THE RPTR THAT SOME OF THE DISTANCES INVOLVED MIGHT BE TOO FAR FOR THE RADAR TO PICK ACFT UP, ESPECIALLY AT THE LOWER ALTS. RPTR INDICATED THAT OTHER RPTS WOULD BE SENT TO ASRS IF THE CONDITIONS OCCUR AGAIN.

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.