Narrative:

The piper seneca departed bowing field/king county international airport (bfi) approved for a 'valley departure' (attachment a). The intended destination was auburn municipal airport (S50). Bfi WX was VFR, clear with 50 mi visibility. The seneca pilot remained on the bfi tower frequency throughout the departure procedure, until approximately over the kent VFR chkpoint on the seattle VFR terminal area chart (attachment B). The tower frequency was monitored this far south because an aeronautical chart bulletin published in the mar/94 edition of the northwest united stated airport facility directory extends the southern limit of the bfi class D airspace. Over kent, the seneca pilot changed to the published auburn CTAF (uncontrolled airport) and began monitoring the traffic pattern activity. The runway in use at auburn was runway 34. The seneca pilot's intent was to continue on a southerly course and make a direct downwind entry into the auburn traffic pattern for runway 34, and to report entering downwind abeam the charted theaters. When approaching the northern edge of the theaters, the seneca pilot observed a single-engine airplane at about 11 O'clock, roughly 1000 ft ahead and about 150 ft lower, northbound in a left climbing turn. The seneca pilot immediately made a left climbing turn to prevent a possible collision. The left turn was continued over the theaters for 360 degrees. Upon rollout on a magnetic heading of about 160, the pilot maintained visual contact with the single-engine aircraft which was then established on downwind, and the seneca pilot reported entering downwind on the CTAF. Immediately following this report, the single-engine aircraft reported downwind. The seneca made additional reports turning on base and again on final. Both aircraft landed safely. When on downwind, the seneca reported downwind on the CTAF and moved the landing gear selector switch to the down position. All 3 wheels failed to extend, and a red 'warning gear unsafe' light remained illuminated. The pilot checked the circuit breakers and cycled the landing gear switch. The gear remained in the up position with the red warning light on. The nosewheel was visually confirmed to be in the up position using the viewing mirror on the left engine nacelle. By this time the seneca had turned to base leg (left traffic). At this point, the pilot elected to abort the approach and depart the traffic pattern to do further investigation of the problem and perform the emergency gear extension checklist procedure. While en route to lake tapps, the landing gear extended to the down and locked position without any action from the pilot. The controled airspace confign between bfi and S50 (auburn) does not allow monitoring of and communications on the auburn CTAF for 10 mi as recommended in the aim (4-9c1). The seneca pilot changed to the auburn CTAF approximately 3-4 mi north of the airport, which did not allow adequate time to fully assess the traffic situation. The single-engine aircraft departing auburn was not aware of the inbound seneca because the seneca did not transmit intentions on the CTAF prior to entering downwind. A non-standard traffic pattern entry was made by the seneca. The seattle class B airspace on the western side of auburn airport precludes making a standard 45 degree entry when arriving from the north, especially in high performance aircraft with a wider turning radius. A short 45 entry could have been attempted by maneuvering close to the edge of the class B airspace, but this situation is potentially more hazardous because collision avoidance maneuvering in this area could result in an infringement of the class B airspace surface area where transport category aircraft may be on short final to sea. In this case, a better method for the seneca to enter the flow of traffic at auburn would be to first overfly the airport well above traffic pattern altitude circling to the left, while assessing the traffic in the pattern and broadcasting intentions on the CTAF. However, this method has a disadvantage because this airspace is near a published VFR flyway zone. Circling in the flyway zone increases the risk of a collision. The traffic patterns at both auburn and crest could be moved to the east side of each airport. This would permit more standard 45 degree entry legs without having to approach the boundary of class B airspace. The traffic pattern altitude at auburn could be raised for noise abatement if the pattern were on the east side. Allowing room for standard traffic pattern entry improves safety at uncontrolled airports because pilots on downwind tend to look for incoming traffic on the 45 degree entry.

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Original NASA ASRS Text

Title: PLT OF AN SMA TWIN ENG ACFT HAD CONFLICT WITH ANOTHER ACFT WHILE ENTERING THE TFC PATTERN TO AN UNCTLED ARPT AND SUBSEQUENTLY EXPERIENCED DIFFICULTY IN EXTENDING THE LNDG GEAR.

Narrative: THE PIPER SENECA DEPARTED BOWING FIELD/KING COUNTY INTL ARPT (BFI) APPROVED FOR A 'VALLEY DEP' (ATTACHMENT A). THE INTENDED DEST WAS AUBURN MUNICIPAL ARPT (S50). BFI WX WAS VFR, CLR WITH 50 MI VISIBILITY. THE SENECA PLT REMAINED ON THE BFI TWR FREQ THROUGHOUT THE DEP PROC, UNTIL APPROX OVER THE KENT VFR CHKPOINT ON THE SEATTLE VFR TERMINAL AREA CHART (ATTACHMENT B). THE TWR FREQ WAS MONITORED THIS FAR S BECAUSE AN AERONAUTICAL CHART BULLETIN PUBLISHED IN THE MAR/94 EDITION OF THE NORTHWEST UNITED STATED ARPT FACILITY DIRECTORY EXTENDS THE SOUTHERN LIMIT OF THE BFI CLASS D AIRSPACE. OVER KENT, THE SENECA PLT CHANGED TO THE PUBLISHED AUBURN CTAF (UNCTLED ARPT) AND BEGAN MONITORING THE TFC PATTERN ACTIVITY. THE RWY IN USE AT AUBURN WAS RWY 34. THE SENECA PLT'S INTENT WAS TO CONTINUE ON A SOUTHERLY COURSE AND MAKE A DIRECT DOWNWIND ENTRY INTO THE AUBURN TFC PATTERN FOR RWY 34, AND TO RPT ENTERING DOWNWIND ABEAM THE CHARTED THEATERS. WHEN APCHING THE NORTHERN EDGE OF THE THEATERS, THE SENECA PLT OBSERVED A SINGLE-ENG AIRPLANE AT ABOUT 11 O'CLOCK, ROUGHLY 1000 FT AHEAD AND ABOUT 150 FT LOWER, NBOUND IN A L CLBING TURN. THE SENECA PLT IMMEDIATELY MADE A L CLBING TURN TO PREVENT A POSSIBLE COLLISION. THE L TURN WAS CONTINUED OVER THE THEATERS FOR 360 DEGS. UPON ROLLOUT ON A MAGNETIC HDG OF ABOUT 160, THE PLT MAINTAINED VISUAL CONTACT WITH THE SINGLE-ENG ACFT WHICH WAS THEN ESTABLISHED ON DOWNWIND, AND THE SENECA PLT RPTED ENTERING DOWNWIND ON THE CTAF. IMMEDIATELY FOLLOWING THIS RPT, THE SINGLE-ENG ACFT RPTED DOWNWIND. THE SENECA MADE ADDITIONAL RPTS TURNING ON BASE AND AGAIN ON FINAL. BOTH ACFT LANDED SAFELY. WHEN ON DOWNWIND, THE SENECA RPTED DOWNWIND ON THE CTAF AND MOVED THE LNDG GEAR SELECTOR SWITCH TO THE DOWN POS. ALL 3 WHEELS FAILED TO EXTEND, AND A RED 'WARNING GEAR UNSAFE' LIGHT REMAINED ILLUMINATED. THE PLT CHKED THE CIRCUIT BREAKERS AND CYCLED THE LNDG GEAR SWITCH. THE GEAR REMAINED IN THE UP POS WITH THE RED WARNING LIGHT ON. THE NOSEWHEEL WAS VISUALLY CONFIRMED TO BE IN THE UP POS USING THE VIEWING MIRROR ON THE L ENG NACELLE. BY THIS TIME THE SENECA HAD TURNED TO BASE LEG (L TFC). AT THIS POINT, THE PLT ELECTED TO ABORT THE APCH AND DEPART THE TFC PATTERN TO DO FURTHER INVESTIGATION OF THE PROB AND PERFORM THE EMER GEAR EXTENSION CHKLIST PROC. WHILE ENRTE TO LAKE TAPPS, THE LNDG GEAR EXTENDED TO THE DOWN AND LOCKED POS WITHOUT ANY ACTION FROM THE PLT. THE CTLED AIRSPACE CONFIGN BTWN BFI AND S50 (AUBURN) DOES NOT ALLOW MONITORING OF AND COMS ON THE AUBURN CTAF FOR 10 MI AS RECOMMENDED IN THE AIM (4-9C1). THE SENECA PLT CHANGED TO THE AUBURN CTAF APPROX 3-4 MI N OF THE ARPT, WHICH DID NOT ALLOW ADEQUATE TIME TO FULLY ASSESS THE TFC SIT. THE SINGLE-ENG ACFT DEPARTING AUBURN WAS NOT AWARE OF THE INBOUND SENECA BECAUSE THE SENECA DID NOT XMIT INTENTIONS ON THE CTAF PRIOR TO ENTERING DOWNWIND. A NON-STANDARD TFC PATTERN ENTRY WAS MADE BY THE SENECA. THE SEATTLE CLASS B AIRSPACE ON THE WESTERN SIDE OF AUBURN ARPT PRECLUDES MAKING A STANDARD 45 DEG ENTRY WHEN ARRIVING FROM THE N, ESPECIALLY IN HIGH PERFORMANCE ACFT WITH A WIDER TURNING RADIUS. A SHORT 45 ENTRY COULD HAVE BEEN ATTEMPTED BY MANEUVERING CLOSE TO THE EDGE OF THE CLASS B AIRSPACE, BUT THIS SIT IS POTENTIALLY MORE HAZARDOUS BECAUSE COLLISION AVOIDANCE MANEUVERING IN THIS AREA COULD RESULT IN AN INFRINGEMENT OF THE CLASS B AIRSPACE SURFACE AREA WHERE TRANSPORT CATEGORY ACFT MAY BE ON SHORT FINAL TO SEA. IN THIS CASE, A BETTER METHOD FOR THE SENECA TO ENTER THE FLOW OF TFC AT AUBURN WOULD BE TO FIRST OVERFLY THE ARPT WELL ABOVE TFC PATTERN ALT CIRCLING TO THE L, WHILE ASSESSING THE TFC IN THE PATTERN AND BROADCASTING INTENTIONS ON THE CTAF. HOWEVER, THIS METHOD HAS A DISADVANTAGE BECAUSE THIS AIRSPACE IS NEAR A PUBLISHED VFR FLYWAY ZONE. CIRCLING IN THE FLYWAY ZONE INCREASES THE RISK OF A COLLISION. THE TFC PATTERNS AT BOTH AUBURN AND CREST COULD BE MOVED TO THE E SIDE OF EACH ARPT. THIS WOULD PERMIT MORE STANDARD 45 DEG ENTRY LEGS WITHOUT HAVING TO APCH THE BOUNDARY OF CLASS B AIRSPACE. THE TFC PATTERN ALT AT AUBURN COULD BE RAISED FOR NOISE ABATEMENT IF THE PATTERN WERE ON THE E SIDE. ALLOWING ROOM FOR STANDARD TFC PATTERN ENTRY IMPROVES SAFETY AT UNCTLED ARPTS BECAUSE PLTS ON DOWNWIND TEND TO LOOK FOR INCOMING TFC ON THE 45 DEG ENTRY.

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.