ATCT controller at mci describes a communications problem peculiar to the B737-700 aircraft.

Attributes
ACN	470309
Time
Date	200004
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mci.airport
State Reference	MO
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	ground : position and hold
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : mci.tower
Make Model Name	Commercial Fixed Wing
Flight Phase	landing : roll
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : radar
ASRS Report	470309
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	atc equipment other atc equipment : mci tower main tstmr other controllera
Resolutory Action	controller : separated traffic
Supplementary
Problem Areas	Aircraft ATC Facility
Primary Problem	Ambiguous
Situations
ATC Facility	communication equipment : mci.tower

Narrative:

While working local, I taxied air carrier X into position and hold. Aircraft on 5 mi final. Traffic just landing rolling out. Air carrier X acknowledged and taxied onto the runway. After landing aircraft cleared, I cleared air carrier X for takeoff, but he could not hear me on the main tower frequency 128.2. Traffic on final was now 3 mi out and I was unable to communicate with the traffic on the runway! This problem has happened enough in the past that I recognized that air carrier X was a B737-700 series. On that type at my facility only at runway 19 only when aircraft on communication #1 does this problem occur only if I have main transmitter. I switched to standby transmitter and was able to clear air carrier X for immediate takeoff in time to avoid a problem with the landing aircraft. This is a dangerous situation that has been known for months but has not been fixed. We are filing a ucr at this facility to get this resolved before an incident/accident occurs. Problem has been known for 5 months now.

Original NASA ASRS Text

Title: ATCT CTLR AT MCI DESCRIBES A COMS PROB PECULIAR TO THE B737-700 ACFT.

Narrative: WHILE WORKING LCL, I TAXIED ACR X INTO POS AND HOLD. ACFT ON 5 MI FINAL. TFC JUST LNDG ROLLING OUT. ACR X ACKNOWLEDGED AND TAXIED ONTO THE RWY. AFTER LNDG ACFT CLRED, I CLRED ACR X FOR TKOF, BUT HE COULD NOT HEAR ME ON THE MAIN TWR FREQ 128.2. TFC ON FINAL WAS NOW 3 MI OUT AND I WAS UNABLE TO COMMUNICATE WITH THE TFC ON THE RWY! THIS PROB HAS HAPPENED ENOUGH IN THE PAST THAT I RECOGNIZED THAT ACR X WAS A B737-700 SERIES. ON THAT TYPE AT MY FACILITY ONLY AT RWY 19 ONLY WHEN ACFT ON COM #1 DOES THIS PROB OCCUR ONLY IF I HAVE MAIN XMITTER. I SWITCHED TO STANDBY XMITTER AND WAS ABLE TO CLR ACR X FOR IMMEDIATE TKOF IN TIME TO AVOID A PROB WITH THE LNDG ACFT. THIS IS A DANGEROUS SIT THAT HAS BEEN KNOWN FOR MONTHS BUT HAS NOT BEEN FIXED. WE ARE FILING A UCR AT THIS FACILITY TO GET THIS RESOLVED BEFORE AN INCIDENT/ACCIDENT OCCURS. PROB HAS BEEN KNOWN FOR 5 MONTHS NOW.

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.