Narrative:

I was returning VFR from vyx to my home airport of pwk. I had just cleared northwest of dpa class D with no incident and good communications with dpa tower. In order to remain well clear of ord class B and simplify navigation, I planned to fly at 2000 ft MSL from dpa VOR to obk VOR and then to pwk. I tuned in pwk ATIS on the communication #2 radio and wrote down the pertinent information. I tuned the communication #1 radio to pwk tower and flew on for a few mins until I got closer to obk. I called pwk tower on communication #1 with my position, intended route of arrival from obk, and intent to land. I heard no reply from the tower so I waited a moment and then called again stating my position as 'over northbrook VOR' and again that I was inbound for landing. Again I heard no reply, so I verified the tower's frequency from my (current) sectional and checked that the radio made noise in its 'test' position, which it did. I thought to check pwk's hours of operation so I looked in the (current) AFD and didn't immediately find the tower's hours. Not wanting to spend too much time 'head down' in a busy VFR environment, I looked at the guide sheet for pwk which I had attached to my kneeboard and saw the tower closing time listed as 'XA00.' I looked at my watch, which was set to zulu time, and saw that it was several mins after XA00. I also looked at and around the airport, which was now in sight, and saw no traffic. Believing that the tower had just closed and I was now dealing with a nontwred airport, I made my next call to 'palwaukee traffic' on the CTAF/tower frequency of 119.9 per nontwred self-announce procedure. I gave my distance from the VOR and reported inbound with intent to land. I called again shortly, giving position as 5 mi out, 'landing runway 12, correction 16.' on short final, I called short final landing runway 16. I looked up from my visual check of the GS to see a light single engine low wing aircraft, blue and white, making a climbing left turn above and to the right of me. The other aircraft was clear of me and our flight paths were divergent at the time so no evasive was necessary. I remember being very startled and thinking that the other aircraft had made a serious error by a) not announcing his/her actions over the CTAF, and B) departing on the opposite runway from the one I had twice announced my intent to land on. Somewhat rattled, I made my landing on runway 16 and turned off runway 16 to taxiway east and announced 'clear of runway 16 on taxiway B' (the 2 signs were close to each other). I later correctly announced that I was 'on taxiway east headed to area X,' then parked and announced clear of all txwys. After I stopped the engine and was collecting my belongings, the other aircraft's silence on the radio and the loss of separation began to concern me. A truck from one of the FBO's on the field arrived and informed me that I was to call the tower. Postevent: I called the tower and the person who replied asked me if I 'knew that we had a tower here.' I said that I did, but believed them to be closed at XA00Z. He indicated that the tower was active until YY00 (XA00 local) and that 'this is a very busy airport.' he further indicated that my xmissions had been received, as someone (either a controller or another pilot) had joked about my announcing my radio calls to 'palwaukee traffic.' he also asked if I had heard his instructions to me and I replied that I had not. Anxious, wanting to solve the problem, and recalling some odd behavior with the frequency selector on communication #1 (see below). I speculated on the possibility of there being some trouble with the radio. He reminded me of NORDO procedures, which I know, and said that he was going to have to report this event 'in case anyone ever asks what I did about it...' because it was 'his job on the line, too.' the next day, I tested the communication #1 radio on the ground with the aid of a cellular phone and an employee at the FBO. The radio made its appropriate noise in 'test' mode, and picked up ATIS just fine. When I called the FBO on their private frequency, the employee heard me and I heard her reply. I twice had her monitor the tower frequency while I called for a radio check. The FBO employee said that she did not hear my transmission, and the tower did not reply. Whilei'm not an avionics technician, the radio obviously was operating in an intermittent manner: the mechanical frequency indicator seemed to be 'slipping' on its gears in some fashion, and only for a certain range of frequencys. This was probably why I had no difficulty communicating with the other facilities previously, and was a difficult situation to detect and diagnose on the ground, let alone in-flight. Backgnd, contributing factors, prevention: the aircraft I operated was a rental, with older mechanical-indicator radios. While I'm not a very high-time pilot, I have the majority of my time in a more modern aircraft with bendix/king digital- display radios and have always believed that a certified radio will 'do what it says' and either work or not work. I am familiar with the class D requirements for 2-WAY communication, and with NORDO procedures. If I had suspected radio difficulties, I would have circled and looked for the light gun, or just tried calling the tower with communication #2.

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Original NASA ASRS Text

Title: PLT OF A PA28-180 IS UNAWARE OF RADIO PROB, BELIEVES TWR IS CLOSED AND ENTERS CLASS D AIRSPACE WITHOUT CLRNC. HE HAS AN NMAC WITH ACFT DEPARTING OPPOSITE DIRECTION.

Narrative: I WAS RETURNING VFR FROM VYX TO MY HOME ARPT OF PWK. I HAD JUST CLRED NW OF DPA CLASS D WITH NO INCIDENT AND GOOD COMS WITH DPA TWR. IN ORDER TO REMAIN WELL CLR OF ORD CLASS B AND SIMPLIFY NAV, I PLANNED TO FLY AT 2000 FT MSL FROM DPA VOR TO OBK VOR AND THEN TO PWK. I TUNED IN PWK ATIS ON THE COM #2 RADIO AND WROTE DOWN THE PERTINENT INFO. I TUNED THE COM #1 RADIO TO PWK TWR AND FLEW ON FOR A FEW MINS UNTIL I GOT CLOSER TO OBK. I CALLED PWK TWR ON COM #1 WITH MY POS, INTENDED RTE OF ARR FROM OBK, AND INTENT TO LAND. I HEARD NO REPLY FROM THE TWR SO I WAITED A MOMENT AND THEN CALLED AGAIN STATING MY POS AS 'OVER NORTHBROOK VOR' AND AGAIN THAT I WAS INBOUND FOR LNDG. AGAIN I HEARD NO REPLY, SO I VERIFIED THE TWR'S FREQ FROM MY (CURRENT) SECTIONAL AND CHKED THAT THE RADIO MADE NOISE IN ITS 'TEST' POS, WHICH IT DID. I THOUGHT TO CHK PWK'S HRS OF OP SO I LOOKED IN THE (CURRENT) AFD AND DIDN'T IMMEDIATELY FIND THE TWR'S HRS. NOT WANTING TO SPEND TOO MUCH TIME 'HEAD DOWN' IN A BUSY VFR ENVIRONMENT, I LOOKED AT THE GUIDE SHEET FOR PWK WHICH I HAD ATTACHED TO MY KNEEBOARD AND SAW THE TWR CLOSING TIME LISTED AS 'XA00.' I LOOKED AT MY WATCH, WHICH WAS SET TO ZULU TIME, AND SAW THAT IT WAS SEVERAL MINS AFTER XA00. I ALSO LOOKED AT AND AROUND THE ARPT, WHICH WAS NOW IN SIGHT, AND SAW NO TFC. BELIEVING THAT THE TWR HAD JUST CLOSED AND I WAS NOW DEALING WITH A NONTWRED ARPT, I MADE MY NEXT CALL TO 'PALWAUKEE TFC' ON THE CTAF/TWR FREQ OF 119.9 PER NONTWRED SELF-ANNOUNCE PROC. I GAVE MY DISTANCE FROM THE VOR AND RPTED INBOUND WITH INTENT TO LAND. I CALLED AGAIN SHORTLY, GIVING POS AS 5 MI OUT, 'LNDG RWY 12, CORRECTION 16.' ON SHORT FINAL, I CALLED SHORT FINAL LNDG RWY 16. I LOOKED UP FROM MY VISUAL CHK OF THE GS TO SEE A LIGHT SINGLE ENG LOW WING ACFT, BLUE AND WHITE, MAKING A CLBING L TURN ABOVE AND TO THE R OF ME. THE OTHER ACFT WAS CLR OF ME AND OUR FLT PATHS WERE DIVERGENT AT THE TIME SO NO EVASIVE WAS NECESSARY. I REMEMBER BEING VERY STARTLED AND THINKING THAT THE OTHER ACFT HAD MADE A SERIOUS ERROR BY A) NOT ANNOUNCING HIS/HER ACTIONS OVER THE CTAF, AND B) DEPARTING ON THE OPPOSITE RWY FROM THE ONE I HAD TWICE ANNOUNCED MY INTENT TO LAND ON. SOMEWHAT RATTLED, I MADE MY LNDG ON RWY 16 AND TURNED OFF RWY 16 TO TXWY E AND ANNOUNCED 'CLR OF RWY 16 ON TXWY B' (THE 2 SIGNS WERE CLOSE TO EACH OTHER). I LATER CORRECTLY ANNOUNCED THAT I WAS 'ON TXWY E HEADED TO AREA X,' THEN PARKED AND ANNOUNCED CLR OF ALL TXWYS. AFTER I STOPPED THE ENG AND WAS COLLECTING MY BELONGINGS, THE OTHER ACFT'S SILENCE ON THE RADIO AND THE LOSS OF SEPARATION BEGAN TO CONCERN ME. A TRUCK FROM ONE OF THE FBO'S ON THE FIELD ARRIVED AND INFORMED ME THAT I WAS TO CALL THE TWR. POSTEVENT: I CALLED THE TWR AND THE PERSON WHO REPLIED ASKED ME IF I 'KNEW THAT WE HAD A TWR HERE.' I SAID THAT I DID, BUT BELIEVED THEM TO BE CLOSED AT XA00Z. HE INDICATED THAT THE TWR WAS ACTIVE UNTIL YY00 (XA00 LCL) AND THAT 'THIS IS A VERY BUSY ARPT.' HE FURTHER INDICATED THAT MY XMISSIONS HAD BEEN RECEIVED, AS SOMEONE (EITHER A CTLR OR ANOTHER PLT) HAD JOKED ABOUT MY ANNOUNCING MY RADIO CALLS TO 'PALWAUKEE TFC.' HE ALSO ASKED IF I HAD HEARD HIS INSTRUCTIONS TO ME AND I REPLIED THAT I HAD NOT. ANXIOUS, WANTING TO SOLVE THE PROB, AND RECALLING SOME ODD BEHAVIOR WITH THE FREQ SELECTOR ON COM #1 (SEE BELOW). I SPECULATED ON THE POSSIBILITY OF THERE BEING SOME TROUBLE WITH THE RADIO. HE REMINDED ME OF NORDO PROCS, WHICH I KNOW, AND SAID THAT HE WAS GOING TO HAVE TO RPT THIS EVENT 'IN CASE ANYONE EVER ASKS WHAT I DID ABOUT IT...' BECAUSE IT WAS 'HIS JOB ON THE LINE, TOO.' THE NEXT DAY, I TESTED THE COM #1 RADIO ON THE GND WITH THE AID OF A CELLULAR PHONE AND AN EMPLOYEE AT THE FBO. THE RADIO MADE ITS APPROPRIATE NOISE IN 'TEST' MODE, AND PICKED UP ATIS JUST FINE. WHEN I CALLED THE FBO ON THEIR PVT FREQ, THE EMPLOYEE HEARD ME AND I HEARD HER REPLY. I TWICE HAD HER MONITOR THE TWR FREQ WHILE I CALLED FOR A RADIO CHK. THE FBO EMPLOYEE SAID THAT SHE DID NOT HEAR MY XMISSION, AND THE TWR DID NOT REPLY. WHILEI'M NOT AN AVIONICS TECHNICIAN, THE RADIO OBVIOUSLY WAS OPERATING IN AN INTERMITTENT MANNER: THE MECHANICAL FREQ INDICATOR SEEMED TO BE 'SLIPPING' ON ITS GEARS IN SOME FASHION, AND ONLY FOR A CERTAIN RANGE OF FREQS. THIS WAS PROBABLY WHY I HAD NO DIFFICULTY COMMUNICATING WITH THE OTHER FACILITIES PREVIOUSLY, AND WAS A DIFFICULT SIT TO DETECT AND DIAGNOSE ON THE GND, LET ALONE INFLT. BACKGND, CONTRIBUTING FACTORS, PREVENTION: THE ACFT I OPERATED WAS A RENTAL, WITH OLDER MECHANICAL-INDICATOR RADIOS. WHILE I'M NOT A VERY HIGH-TIME PLT, I HAVE THE MAJORITY OF MY TIME IN A MORE MODERN ACFT WITH BENDIX/KING DIGITAL- DISPLAY RADIOS AND HAVE ALWAYS BELIEVED THAT A CERTIFIED RADIO WILL 'DO WHAT IT SAYS' AND EITHER WORK OR NOT WORK. I AM FAMILIAR WITH THE CLASS D REQUIREMENTS FOR 2-WAY COM, AND WITH NORDO PROCS. IF I HAD SUSPECTED RADIO DIFFICULTIES, I WOULD HAVE CIRCLED AND LOOKED FOR THE LIGHT GUN, OR JUST TRIED CALLING THE TWR WITH COM #2.

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.