Narrative:

Departed with 4 passenger. At 1000 ft; I contacted approach to request flight following. After approximately 15-20 min flight at 3000 ft; a loud noise started sounding like severe hail or marbles hitting aircraft. It sounded like noise was from left side of engine. I felt that it was the beginning of a cylinder going bad. I contacted approach and declared an emergency. They acknowledged and informed me that I had 2 airports at 11 O'clock position. After visually locating nearest airport; I stated I had runway in sight. They said it was clear between me and the airport. I cut power for my descent forming a base leg. I asked approach for ZZZ unicom to announce my intentions and that I declared an emergency. As I was turning base to final and dealing with loud unknown sound and panicked passenger; I observed another aircraft on final for runway 26 (opposite direction) headed straight for me since I was final for runway 8. I commenced to ask aircraft to abort his landing and that I was on an emergency final. He continued his landing. I realized he would not stop his landing. I looked for 'plan B' which was the grass and taxiway next to runway. As I kept him in sight; I continued my descent and moved over from runway so as not to hit the other aircraft. Because I continued to avoid second aircraft; I used up too much of the available landing area -- even though I was lower than him; he still did not give way. At the last second before deciding to land in field after runway; I looked at gauges one last time. Oil pressure was good; oil temperature was good; power was good so I pwred up and did a go around to land on runway 26. The engine held together and I made a safe landing. The other aircraft also did a go around and safely landed. Pilot of other aircraft came over and arrogantly started to inform me that I almost killed 8 people. I explained I had declared an emergency. He stated he heard my calls on unicom but thought I was landing at ZZZ because I was calling ZZZ on the unicom which both ZZZ and ZZZ1 share. I landed at ZZZ1 since that was the first airstrip in sight of the 2 airports that are approximately 2 mi apart. The pilot of the other aircraft continued on final and challenged his perceived right-of-way. The mechanic released the aircraft after a thorough inspection and found that a seal around the windshield became detached in-flight and was pounding on the cockpit roof above my head radiating a noise that was as loud as it was. Considering the circumstances; I feel the other pilot greatly added to a tense situation by holding fast and insisting he had the right-of-way. He should have given way as he had a full final to do so I had him in sight during the whole landing process; however; I was dealing with what I thought was possible engine failure and wanted to land as soon as possible at the closest airport in sight.

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Original NASA ASRS Text

Title: A LIGHT AIRCRAFT PILOT DEALING WITH WHAT HE THOUGHT WAS AN ENGINE PROBLEM DECLARED AN EMERGENCY AND DIVERTED TO THE NEAREST AIRPORT. ANOTHER AIRCRAFT LANDING OPP DIRECTION WOULD NOT YIELD RIGHT OF WAY.

Narrative: DEPARTED WITH 4 PAX. AT 1000 FT; I CONTACTED APCH TO REQUEST FLT FOLLOWING. AFTER APPROX 15-20 MIN FLT AT 3000 FT; A LOUD NOISE STARTED SOUNDING LIKE SEVERE HAIL OR MARBLES HITTING ACFT. IT SOUNDED LIKE NOISE WAS FROM L SIDE OF ENG. I FELT THAT IT WAS THE BEGINNING OF A CYLINDER GOING BAD. I CONTACTED APCH AND DECLARED AN EMER. THEY ACKNOWLEDGED AND INFORMED ME THAT I HAD 2 ARPTS AT 11 O'CLOCK POS. AFTER VISUALLY LOCATING NEAREST ARPT; I STATED I HAD RWY IN SIGHT. THEY SAID IT WAS CLR BTWN ME AND THE ARPT. I CUT PWR FOR MY DSCNT FORMING A BASE LEG. I ASKED APCH FOR ZZZ UNICOM TO ANNOUNCE MY INTENTIONS AND THAT I DECLARED AN EMER. AS I WAS TURNING BASE TO FINAL AND DEALING WITH LOUD UNKNOWN SOUND AND PANICKED PAX; I OBSERVED ANOTHER ACFT ON FINAL FOR RWY 26 (OPPOSITE DIRECTION) HEADED STRAIGHT FOR ME SINCE I WAS FINAL FOR RWY 8. I COMMENCED TO ASK ACFT TO ABORT HIS LNDG AND THAT I WAS ON AN EMER FINAL. HE CONTINUED HIS LNDG. I REALIZED HE WOULD NOT STOP HIS LNDG. I LOOKED FOR 'PLAN B' WHICH WAS THE GRASS AND TXWY NEXT TO RWY. AS I KEPT HIM IN SIGHT; I CONTINUED MY DSCNT AND MOVED OVER FROM RWY SO AS NOT TO HIT THE OTHER ACFT. BECAUSE I CONTINUED TO AVOID SECOND ACFT; I USED UP TOO MUCH OF THE AVAILABLE LNDG AREA -- EVEN THOUGH I WAS LOWER THAN HIM; HE STILL DID NOT GIVE WAY. AT THE LAST SECOND BEFORE DECIDING TO LAND IN FIELD AFTER RWY; I LOOKED AT GAUGES ONE LAST TIME. OIL PRESSURE WAS GOOD; OIL TEMP WAS GOOD; PWR WAS GOOD SO I PWRED UP AND DID A GAR TO LAND ON RWY 26. THE ENG HELD TOGETHER AND I MADE A SAFE LNDG. THE OTHER ACFT ALSO DID A GAR AND SAFELY LANDED. PLT OF OTHER ACFT CAME OVER AND ARROGANTLY STARTED TO INFORM ME THAT I ALMOST KILLED 8 PEOPLE. I EXPLAINED I HAD DECLARED AN EMER. HE STATED HE HEARD MY CALLS ON UNICOM BUT THOUGHT I WAS LNDG AT ZZZ BECAUSE I WAS CALLING ZZZ ON THE UNICOM WHICH BOTH ZZZ AND ZZZ1 SHARE. I LANDED AT ZZZ1 SINCE THAT WAS THE FIRST AIRSTRIP IN SIGHT OF THE 2 ARPTS THAT ARE APPROX 2 MI APART. THE PLT OF THE OTHER ACFT CONTINUED ON FINAL AND CHALLENGED HIS PERCEIVED RIGHT-OF-WAY. THE MECH RELEASED THE ACFT AFTER A THOROUGH INSPECTION AND FOUND THAT A SEAL AROUND THE WINDSHIELD BECAME DETACHED INFLT AND WAS POUNDING ON THE COCKPIT ROOF ABOVE MY HEAD RADIATING A NOISE THAT WAS AS LOUD AS IT WAS. CONSIDERING THE CIRCUMSTANCES; I FEEL THE OTHER PLT GREATLY ADDED TO A TENSE SITUATION BY HOLDING FAST AND INSISTING HE HAD THE RIGHT-OF-WAY. HE SHOULD HAVE GIVEN WAY AS HE HAD A FULL FINAL TO DO SO I HAD HIM IN SIGHT DURING THE WHOLE LNDG PROCESS; HOWEVER; I WAS DEALING WITH WHAT I THOUGHT WAS POSSIBLE ENG FAILURE AND WANTED TO LAND ASAP AT THE CLOSEST ARPT IN SIGHT.

Data retrieved from NASA's ASRS site as of May 2009 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.