Narrative:

Jul/sun/92, PM00Z, 10 NM north of 10C, conditions approximately 4000 scattered, visibility about 20 mi, wind out of the west, traffic using runway 27. PM05Z 122.8: 'galt traffic, aircraft identify, is 6 north, inbound landing galt.' I was descending out of 1900 for 1700 using current dpa ATIS altimeter setting. PM08Z: I was 1.5 north of galt on a mid-field crosswind to runway 27 (see diagram). As I was about to announce my crosswind leg, I heard 'aircraft Y XXX upwind leg galt.' I looked for the traffic and saw a plane at my 10 O'clock, high, crossing above me about 100 ft higher. I then announced, 'galt traffic, aircraft X, mid-field crosswind, 27 galt, going under the aircraft Y.' PM11Z: I landed on 27, and the aircraft Y landed a min or 2 after me. PM16Z: the aircraft Y pilot came over to me and said, 'that was a pretty dumb stunt, cutting underneath me.' I asked him what tpa was at this field and I think he said '...1800 or 1900 ft.' we argued for a while, our interchange was not productive. Comments/analysis: this seems like the classical incident where a low wing plane from above does not see the high wing plane beneath, and vice versa. Only after some thought did I realize why I didn't see the aircraft Y. He was blanked from my field of view by my left wing. I was no doubt also in the blind area beneath his right wing. I should have made a more complete scan during my crosswind leg entry, including a scan for planes higher than tpa. I should also have asked my wife to help look for traffic (she usually does, but was engrossed in a book during this particular pattern entry). It may have helped if both planes were at the tpa in the pattern. I personally have some confusion as how to enter the pattern when the direction of flight toward the airport crosses the runway before crossing the downwind leg. The diagram in the aim (figure 4-54(1), jun/xx/92 aim) does not treat this case. Instructors have advocated several pattern entry techniques when the optimum direct 45 degree downwind entry is not feasible: 1) make an overhead approach to the center of the airport above tpa and then descend while maneuvering to downwind leg. 2) make a crosswind approach at tpa to the center of the field and enter a downwind at mid field. 3) enter an upwind leg at tpa and fly a tighter than normal pattern to avoid departing climbing traffic. 4) fly a 5 mi radius arc around the airport so as to always enter the downwind leg from a 45 degree angle. I feel that standardization of aircraft flow into the pattern at uncontrolled airports is needed. I had a moderately close call, but it could have been a lot worse! I would appreciate advice on avoiding these kinds of close encounters. Callback conversation with reporter revealed the following: tpa is 1675 ft MSL. It was recommended to the reporter that a good procedure for coming across, or over, a non controled airport traffic pattern is to go over the airport at an altitude of approximately 500 ft or more above the traffic pattern. This is also a good altitude to circle the airport to observe the wind and runway to use when replies are not coming from unicom. Then fly perpendicular to the downwind leg away from the airport and start letting down to pattern altitude outside of the downwind leg. Then fly into the downwind leg on a 45 degree angle to enter the pattern at pattern altitude. The reporter stated that none of the local instructors had used this method at the non controled airport at which he learned to fly. He stated his appreciation for the callback and advised that he would pass on this advice to the other airmen. He further stated that it may save some lives.

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Original NASA ASRS Text

Title: NMAC BTWN 2 SMA ACFT AT A NON TWR NON CTLED ARPT.

Narrative: JUL/SUN/92, PM00Z, 10 NM N OF 10C, CONDITIONS APPROX 4000 SCATTERED, VISIBILITY ABOUT 20 MI, WIND OUT OF THE W, TFC USING RWY 27. PM05Z 122.8: 'GALT TFC, ACFT IDENT, IS 6 N, INBOUND LNDG GALT.' I WAS DSNDING OUT OF 1900 FOR 1700 USING CURRENT DPA ATIS ALTIMETER SETTING. PM08Z: I WAS 1.5 N OF GALT ON A MID-FIELD XWIND TO RWY 27 (SEE DIAGRAM). AS I WAS ABOUT TO ANNOUNCE MY XWIND LEG, I HEARD 'ACFT Y XXX UPWIND LEG GALT.' I LOOKED FOR THE TFC AND SAW A PLANE AT MY 10 O'CLOCK, HIGH, XING ABOVE ME ABOUT 100 FT HIGHER. I THEN ANNOUNCED, 'GALT TFC, ACFT X, MID-FIELD XWIND, 27 GALT, GOING UNDER THE ACFT Y.' PM11Z: I LANDED ON 27, AND THE ACFT Y LANDED A MIN OR 2 AFTER ME. PM16Z: THE ACFT Y PLT CAME OVER TO ME AND SAID, 'THAT WAS A PRETTY DUMB STUNT, CUTTING UNDERNEATH ME.' I ASKED HIM WHAT TPA WAS AT THIS FIELD AND I THINK HE SAID '...1800 OR 1900 FT.' WE ARGUED FOR A WHILE, OUR INTERCHANGE WAS NOT PRODUCTIVE. COMMENTS/ANALYSIS: THIS SEEMS LIKE THE CLASSICAL INCIDENT WHERE A LOW WING PLANE FROM ABOVE DOES NOT SEE THE HIGH WING PLANE BENEATH, AND VICE VERSA. ONLY AFTER SOME THOUGHT DID I REALIZE WHY I DIDN'T SEE THE ACFT Y. HE WAS BLANKED FROM MY FIELD OF VIEW BY MY L WING. I WAS NO DOUBT ALSO IN THE BLIND AREA BENEATH HIS R WING. I SHOULD HAVE MADE A MORE COMPLETE SCAN DURING MY XWIND LEG ENTRY, INCLUDING A SCAN FOR PLANES HIGHER THAN TPA. I SHOULD ALSO HAVE ASKED MY WIFE TO HELP LOOK FOR TFC (SHE USUALLY DOES, BUT WAS ENGROSSED IN A BOOK DURING THIS PARTICULAR PATTERN ENTRY). IT MAY HAVE HELPED IF BOTH PLANES WERE AT THE TPA IN THE PATTERN. I PERSONALLY HAVE SOME CONFUSION AS HOW TO ENTER THE PATTERN WHEN THE DIRECTION OF FLT TOWARD THE ARPT CROSSES THE RWY BEFORE XING THE DOWNWIND LEG. THE DIAGRAM IN THE AIM (FIGURE 4-54(1), JUN/XX/92 AIM) DOES NOT TREAT THIS CASE. INSTRUCTORS HAVE ADVOCATED SEVERAL PATTERN ENTRY TECHNIQUES WHEN THE OPTIMUM DIRECT 45 DEG DOWNWIND ENTRY IS NOT FEASIBLE: 1) MAKE AN OVERHEAD APCH TO THE CTR OF THE ARPT ABOVE TPA AND THEN DSND WHILE MANEUVERING TO DOWNWIND LEG. 2) MAKE A XWIND APCH AT TPA TO THE CTR OF THE FIELD AND ENTER A DOWNWIND AT MID FIELD. 3) ENTER AN UPWIND LEG AT TPA AND FLY A TIGHTER THAN NORMAL PATTERN TO AVOID DEPARTING CLBING TFC. 4) FLY A 5 MI RADIUS ARC AROUND THE ARPT SO AS TO ALWAYS ENTER THE DOWNWIND LEG FROM A 45 DEG ANGLE. I FEEL THAT STANDARDIZATION OF ACFT FLOW INTO THE PATTERN AT UNCTLED ARPTS IS NEEDED. I HAD A MODERATELY CLOSE CALL, BUT IT COULD HAVE BEEN A LOT WORSE! I WOULD APPRECIATE ADVICE ON AVOIDING THESE KINDS OF CLOSE ENCOUNTERS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: TPA IS 1675 FT MSL. IT WAS RECOMMENDED TO THE RPTR THAT A GOOD PROC FOR COMING ACROSS, OR OVER, A NON CTLED ARPT TFC PATTERN IS TO GO OVER THE ARPT AT AN ALT OF APPROX 500 FT OR MORE ABOVE THE TFC PATTERN. THIS IS ALSO A GOOD ALT TO CIRCLE THE ARPT TO OBSERVE THE WIND AND RWY TO USE WHEN REPLIES ARE NOT COMING FROM UNICOM. THEN FLY PERPENDICULAR TO THE DOWNWIND LEG AWAY FROM THE ARPT AND START LETTING DOWN TO PATTERN ALT OUTSIDE OF THE DOWNWIND LEG. THEN FLY INTO THE DOWNWIND LEG ON A 45 DEG ANGLE TO ENTER THE PATTERN AT PATTERN ALT. THE RPTR STATED THAT NONE OF THE LCL INSTRUCTORS HAD USED THIS METHOD AT THE NON CTLED ARPT AT WHICH HE LEARNED TO FLY. HE STATED HIS APPRECIATION FOR THE CALLBACK AND ADVISED THAT HE WOULD PASS ON THIS ADVICE TO THE OTHER AIRMEN. HE FURTHER STATED THAT IT MAY SAVE SOME LIVES.

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.