Date: 201605
Local time of day: 1201-1800
Location: ZFW.ARTCC, TX
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZFW
ATC / advisory: Center ZFW
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Troubleshooting; Situational Awareness; Confusion; Communication Breakdown; Distraction
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance
Contributing factors: Environment - Non Weather Related; Human Factors; Procedure; ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: During the time in question I was working the radar position on Decod High ZFW42. A radar handoff and radar associate were also on the sector. D10 approach requests 7 miles in trail for like types; 9 miles in trail behind heavy. This requires Decod High to provide Seaver Low with 10 miles in trail like type aircraft. The distance from the Seaver Low boundary inside Decod High to the ZME/Decod High boundary is approximately 110 miles. ZME was required to give 15 miles in trail on the FEWWW transition and 10 miles in trail on the RRNET transition. The problem with this restriction is many times the aircraft are still tied up between the two transitions and vectors for spacing are still required even with that spacing. The other issue is Decod High frequencies are very poor in quality; forcing numerous repeats of transmissions. Transmissions are often blocked by other aircraft making initial calls on frequency. This happened numerous times during this period. Volume was very high during this session and the two streams coming into DFW were not blending well due to too many aircraft in the same geographic area at the same time. Aircraft on the RRNET transition needed headings of 150 degrees then back to 300 degrees and FEWWW aircraft needed 300 degree headings with turns direct to the SEEVR intersection later. Many of these instructions had to be repeated due to blocked transmissions. The two aircraft in question were both on vectors (as were several other aircraft) and I believe one of the aircraft did not receive a turn due to a blocked transmission. The aircraft may have not received the assigned speed.Adjacent center metering in ZME would greatly help space the DFW arrivals in Decod High. When every arrival needs to be vectored the further out the spacing occurs the less dramatic the turns and speed instructions are for each aircraft. 15 or 20 miles in trail on both routes may have helped reduce the level of sequencing and reduced the level of blocked transmissions. I instructed my radar associate on sector to hold two aircraft in ZME. I probably should have held the RRNET stream letting the FEWWW stream into SEEVR Low then bring in the RRNET stream. The frequencies have been poor quality. They need to be fixed or replaced. When 20 aircraft are on frequency and 12 need vectors; speeds; and descent clearances in a short period of time it is extremely important that the radios are in perfect working order. Too often controllers have to repeat instructions due to the poor quality of those radios.




Synopsis: ZFW Controller reported of flow control problems into the sector and bad radios in this same area.