AGRICULTURAL PLANE HAS NMAC WITH C152 ON TKOF AT NON TWR ARPT.

Narrative

I DEPARTED WALLA WALLA ARPT WITH THE SECOND LOAD OF THE EVENING IN A G164B TO SPRAY A FIELD APPROX 5-6 MI ENE OF WALLA WALLA. POS AND STROBE LIGHTS WERE ON AT THIS TIME. ON THE FIRST TKOF THE TWR WAS OPEN AND I REQUESTED RWY 2 INTXN C WITH A R TURNOUT. THERE WAS CONFLICTING TFC SO I AMENDED MY REQUEST TO RWY 20 AT INTXN C TO EXPEDITE OPS. NORMALLY WHEN CONDITIONS ALLOW; I USE RWY 2 FOR OPS THAT INVOLVE NE TO SE DEPS DUE TO THE PROX OF TOWN WITH ITS RESIDENCES AND BUSINESS LOCATIONS AND THE NOISE FROM A RADIAL ENG AND A HVY ACFT. THE SECOND TKOF WAS MADE AFTER THE TWR HAD CLOSED FOR THE EVENING ON RWY 2 AT INTXN C WITH A R TURN DEP. APPROX 1/2 WAY THROUGH THIS LOAD THE FLAGGER USED TO MARK MY POS IN THE FIELD MALFUNCTIONED FORCING ME TO RETURN TO WALLA WALLA. I LANDED ON RWY 20; EXITED AT INTXN B AND TAXIED TO THE HANGAR WHERE I CORRECTED THE PROB. THE CHEMICAL I WAS APPLYING WILL LOSE ITS POTENCY ONCE IT IS MIXED WITH WATER IF IT IS NOT APPLIED IN A TIMELY MANNER. THIS BEING THE CASE; AND WITH THE SUN SETTING; I WAS IN A HURRY TO GET BACK TO THE FIELD. I STRAPPED BACK INTO THE ACFT; STARTED THE ENG; PUT MY HELMET ON WHICH HAD MY RADIO SPEAKERS IN IT AND STARTED BACK TO RWY 2 AT INTXN C. I ANNOUNCED 'AGCAT TAKING RWY 2; INTXN C; R TURNOUT.' I DID NOT SEE ANY OTHER TFC IN THE AIR OR ON THE GND AT THIS TIME AND THERE WAS NO RADIO CALL FROM ANY ACFT AT WALLA WALLA TO INDICATE ANY POTENTIAL CONFLICT. WHEN I WAS ADDING PWR AS I WAS STRAIGHTENING OUT MY TURN FROM INTXN C TO RWY 2; I OBSERVED A CESSNA 150 OR 152 WITH NO VISIBLE LIGHTS ON; COMING AT ME; TAKING OFF FROM RWY 20. I WOULD ESTIMATE WHEN I FIRST SAW HIM WE WERE SEVERAL HUNDRED YARDS APART AND CLOSING. I WENT TO THE W SIDE OF THE RWY AND HE WENT TO THE E. WE PASSED BTWN INTXN B AND C AND WE BOTH CONTINUED TO TKOF. I DON'T KNOW WHAT POS RPTS WERE MADE BY THE CESSNA OR HIS LOCATION WHEN ANY RPTS WERE MADE. I BELIEVE THAT HE HAD BEEN DOING PATTERN WORK EARLIER. WHETHER OR NOT WE WERE AFTER OFFICIAL SUNSET; IT WAS CLOSE ENOUGH THAT COMMON SENSE WOULD DICTATE THAT HE HAVE LIGHTS ON TO FACILITATE BEING SEEN. IF A CESSNA 150 FLIES WIDE OR LONG PATTERN AND RPTS TURNING FINAL 2-3 MI OUT; SEVERAL MINS CAN PASS BEFORE HE GETS BACK TO THE RWY AND NO ADDITIONAL RPTS ARE REQUIRED. I SHOULD HAVE SEEN THE CESSNA. HE SHOULD HAVE HAD HIS LIGHTS ON. I DID NOT HEAR HIM RPT FINAL AND I CANNOT SAY IF I WAS EVEN IN THE ACFT WHEN OR IF HE DID. WHEN I ANNOUNCED MY INTENTIONS TO TKOF RWY 2 AT INTXN C THERE WAS NO RADIO CALL FROM ANYONE TO INDICATE A CONFLICT. IN AN UNCTLED ENVIRONMENT WHERE IT IS SEE AND BE SEEN; I FAILED TO SEE HIM BUT I DON'T THINK HE DID ANYTHING TO HELP AVOID THE SIT; WHETHER IT BE HAVING HIS LIGHTS ON OR BY COMMUNICATING WITH ANY OTHER TFC IN THE VICINITY.