Radio communication problem almost causes loss of separation.

Attributes
ACN	242496
Time
Date	199305
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : har
State Reference	PA
Altitude	msl bound lower : 24000 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	enroute airway : zob
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 11600 flight time type : 9000
ASRS Report	242496
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

On our initial descent into phl, we were stepped down to FL250. We were in contact with ZOB on frequency 119.92. About 5 mins earlier we had heard some taxi instructions on that frequency as well as some vectoring from an approach control. We asked ZOB if he could still read us, just to make sure that our radio was still on the correct frequency. He responded and also mentioned that they have been experiencing some similar problems with that frequency. So out of the blue, ZOB asked us to descend to FL240 and expedite descent, which we did. He later sent us to ZNY on 132.2. Even that transmission was half garbled at that time. We later found out that another aircraft at FL250 was heading for the same VOR as we were. In a phone conversation with an ATC supervisor, the 2 aircraft in question complied fully with ATC separation guidelines. However, the potential was there, because they could not establish radio communication with the other aircraft either. Apparently ZOB had attempted to call us twice before and made contact on the third try. I am not really sure why we did not hear the first 2 radio xmissions, but I suspect there might be problems with that radio frequency 119.92.

Original NASA ASRS Text

Title: RADIO COM PROB ALMOST CAUSES LOSS OF SEPARATION.

Narrative: ON OUR INITIAL DSCNT INTO PHL, WE WERE STEPPED DOWN TO FL250. WE WERE IN CONTACT WITH ZOB ON FREQ 119.92. ABOUT 5 MINS EARLIER WE HAD HEARD SOME TAXI INSTRUCTIONS ON THAT FREQ AS WELL AS SOME VECTORING FROM AN APCH CTL. WE ASKED ZOB IF HE COULD STILL READ US, JUST TO MAKE SURE THAT OUR RADIO WAS STILL ON THE CORRECT FREQ. HE RESPONDED AND ALSO MENTIONED THAT THEY HAVE BEEN EXPERIENCING SOME SIMILAR PROBS WITH THAT FREQ. SO OUT OF THE BLUE, ZOB ASKED US TO DSND TO FL240 AND EXPEDITE DSCNT, WHICH WE DID. HE LATER SENT US TO ZNY ON 132.2. EVEN THAT XMISSION WAS HALF GARBLED AT THAT TIME. WE LATER FOUND OUT THAT ANOTHER ACFT AT FL250 WAS HDG FOR THE SAME VOR AS WE WERE. IN A PHONE CONVERSATION WITH AN ATC SUPVR, THE 2 ACFT IN QUESTION COMPLIED FULLY WITH ATC SEPARATION GUIDELINES. HOWEVER, THE POTENTIAL WAS THERE, BECAUSE THEY COULD NOT ESTABLISH RADIO COM WITH THE OTHER ACFT EITHER. APPARENTLY ZOB HAD ATTEMPTED TO CALL US TWICE BEFORE AND MADE CONTACT ON THE THIRD TRY. I AM NOT REALLY SURE WHY WE DID NOT HEAR THE FIRST 2 RADIO XMISSIONS, BUT I SUSPECT THERE MIGHT BE PROBS WITH THAT RADIO FREQ 119.92.

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.