C501 crew had VHF radio problems while descending to an airport within dc ADIZ.

Attributes
ACN	613149
Time
Date	200403
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : brv.vortac
State Reference	VA
Altitude	msl single value : 20000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pct.tracon
Operator	general aviation : corporate
Make Model Name	Citation I/SP
Operating Under FAR Part	Part 91
Flight Phase	cruise : level descent : intermediate altitude
Route In Use	arrival star : coat t
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : multi engine
Experience	flight time last 90 days : 112 flight time total : 5132 flight time type : 1123
ASRS Report	613149
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : cfi pilot : atp
Experience	flight time last 90 days : 92 flight time total : 3012 flight time type : 21
ASRS Report	613148
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance controller : provided flight assist flight crew : overcame equipment problem other
Consequence	other
Supplementary
Problem Areas	Airspace Structure Aircraft
Primary Problem	Aircraft

Narrative:

On the above date the aircraft experienced a gradual loss of communication effectiveness. While we were able to hear the center and approach to some extent, ATC was not able to hear us consistently. We were on the coatt arrival into the dc metroplex for a landing at hef. We were level at FL200 when the failure occurred. Our last reliable received transmission was to cross falko intersection at 10000 ft and 250 KTS. Upon arrival at falko and being unable to communicate with ATC we declared an emergency by broadcasting in the blind on 121.5 and squawking 7700 for 1 min and then changing to 7600. We broadcast our intention to descend wbound and remain VFR and remain clear of the ADIZ. At this time we received a transmission to contact pct TRACON on 124.65. We were able to communicate on a limited basis. We advised them we were going to divert to W66. The captain then specifically requested that ATC advise us if they would allow us to land at our original destination of hef, as there were facilities there for the repair of the aircraft. Plus that was where the passenger wanted to land anyway. The captain specifically requested that ATC allow the emergency aircraft to land at hef. ATC gave us permission to enter the ADIZ as an emergency aircraft. We then landed without incident.

Original NASA ASRS Text

Title: C501 CREW HAD VHF RADIO PROBS WHILE DSNDING TO AN ARPT WITHIN DC ADIZ.

Narrative: ON THE ABOVE DATE THE ACFT EXPERIENCED A GRADUAL LOSS OF COM EFFECTIVENESS. WHILE WE WERE ABLE TO HEAR THE CTR AND APCH TO SOME EXTENT, ATC WAS NOT ABLE TO HEAR US CONSISTENTLY. WE WERE ON THE COATT ARR INTO THE DC METROPLEX FOR A LNDG AT HEF. WE WERE LEVEL AT FL200 WHEN THE FAILURE OCCURRED. OUR LAST RELIABLE RECEIVED XMISSION WAS TO CROSS FALKO INTXN AT 10000 FT AND 250 KTS. UPON ARR AT FALKO AND BEING UNABLE TO COMMUNICATE WITH ATC WE DECLARED AN EMER BY BROADCASTING IN THE BLIND ON 121.5 AND SQUAWKING 7700 FOR 1 MIN AND THEN CHANGING TO 7600. WE BROADCAST OUR INTENTION TO DSND WBOUND AND REMAIN VFR AND REMAIN CLR OF THE ADIZ. AT THIS TIME WE RECEIVED A XMISSION TO CONTACT PCT TRACON ON 124.65. WE WERE ABLE TO COMMUNICATE ON A LIMITED BASIS. WE ADVISED THEM WE WERE GOING TO DIVERT TO W66. THE CAPT THEN SPECIFICALLY REQUESTED THAT ATC ADVISE US IF THEY WOULD ALLOW US TO LAND AT OUR ORIGINAL DEST OF HEF, AS THERE WERE FACILITIES THERE FOR THE REPAIR OF THE ACFT. PLUS THAT WAS WHERE THE PAX WANTED TO LAND ANYWAY. THE CAPT SPECIFICALLY REQUESTED THAT ATC ALLOW THE EMER ACFT TO LAND AT HEF. ATC GAVE US PERMISSION TO ENTER THE ADIZ AS AN EMER ACFT. WE THEN LANDED WITHOUT INCIDENT.

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.