<< >> NASA ASRS Report 249359, August 1993

Small aircraft pilot doing instrument approachs has frequency interference from a tower approximately 150 mi south.

Attributes
ACN	249359
Time
Date	199308
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : chs
State Reference	SC
Altitude	msl bound lower : 1500 msl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : chs tracon : phl
Operator	general aviation : instructional
Make Model Name	Small Aircraft
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial pilot : cfi
Experience	flight time last 90 days : 150 flight time total : 1230 flight time type : 400
ASRS Report	249359
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other
Situations
ATC Facility	other physical facility

Narrative:

This flight was an instrument training flight. We were being radar vectored for an ILS approach to runway 15 at chs by charleston approach. Controller workload was heavy. Chs approach happens to share frequency 120.70 with daytona beach tower. Aircraft at altitudes above plus or minus 1500 ft MSL can pick up xmissions from other aircraft at both locations. This caused a lot of interference, xmissions blocking off other ones. The chs controller had to repeat his instructions constantly because he was being blocked by aircraft at daytona. This increased his already very high workload. It also worked at confusing for some inexperienced pilots, hearing xmissions that were from a completely different nature. All in all, this is a pretty annoying, if not dangerous, situation. It would be a great relief if the frequency at one of the locations could change by only 0.05!

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Original NASA ASRS Text

Title: SMA PLT DOING INST APCHS HAS FREQ INTERFERENCE FROM A TWR APPROX 150 MI S.

Narrative: THIS FLT WAS AN INST TRAINING FLT. WE WERE BEING RADAR VECTORED FOR AN ILS APCH TO RWY 15 AT CHS BY CHARLESTON APCH. CTLR WORKLOAD WAS HVY. CHS APCH HAPPENS TO SHARE FREQ 120.70 WITH DAYTONA BEACH TWR. ACFT AT ALTS ABOVE PLUS OR MINUS 1500 FT MSL CAN PICK UP XMISSIONS FROM OTHER ACFT AT BOTH LOCATIONS. THIS CAUSED A LOT OF INTERFERENCE, XMISSIONS BLOCKING OFF OTHER ONES. THE CHS CTLR HAD TO REPEAT HIS INSTRUCTIONS CONSTANTLY BECAUSE HE WAS BEING BLOCKED BY ACFT AT DAYTONA. THIS INCREASED HIS ALREADY VERY HIGH WORKLOAD. IT ALSO WORKED AT CONFUSING FOR SOME INEXPERIENCED PLTS, HEARING XMISSIONS THAT WERE FROM A COMPLETELY DIFFERENT NATURE. ALL IN ALL, THIS IS A PRETTY ANNOYING, IF NOT DANGEROUS, SIT. IT WOULD BE A GREAT RELIEF IF THE FREQ AT ONE OF THE LOCATIONS COULD CHANGE BY ONLY 0.05!

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.