Narrative:

CTAF frequency was monitored and appropriate calls were made north northwest of [the airport] at approximately 10 NM; 5 NM; 2 NM; and when 'overhead the numbers' of runway 26. In addition to this being a nearly direct route to the destination; direct over flight of the airport was; in my mind; the safest route through the busy traffic area/corridor and nearby airports; the altitude being flown (6;800 ft MSL) was well above the traffic pattern. I heard several CTAF advisory calls made by airplanes in the vicinity: one was approaching from the east at about ten miles; one was entering a downwind for runway 08; another had just landed and was taxiing for parking on the ramp. I was able to obtain a visual on the traffic except for the aircraft arriving from the east; however; I did 'see' all airborne traffic on my traffic awareness system (TAS) display. At no time did I visually observe or see any traffic on my TAS other than the participating aircraft making calls on the CTAF frequency. As I neared the approach end of runway 26; I made a call of my position on the CTAF frequency with altitude. I was heading approximately 165 degrees. Within five seconds; I observed a tow plane with glider on tow pass below; left to right; and slightly ahead of my position on a westerly heading. Maneuver was not required; but in any case would have been too late if it had been necessary. At no time did I hear any called traffic indicating a tow plane with glider in the vicinity of the airport. There was no indication of such close proximity traffic on my TAS; and no 'traffic alert' was issued by my TAS; I concluded that no transponder was in use by the tow plane. I made a call on the CTAF frequency and asked 'if the tow plane was on the traffic advisory frequency.' no answer. I again made a call requesting a response from the tow plane. This time I received an answer from the pilot of the glider on tow. I asked the glider pilot if he had seen or heard my traffic calls; he said 'no'. I then asked unicom for tow plane info and I stated that I would call the tow operator at the conclusion of my flight (in about one hour). By this time I was approaching [airport] airspace and had to switch up that frequency in order to request transit through that airspace. After the glider on tow passed below and from left to right in front of us; I informed my crew about the near miss. The crew member; who was seated in the left rear forward facing seat; stated that she had seen 'two shadows; very closely spaced; on the ground off to our left'; but she didn't say anything because she was trying to 'figure out' what they were. However; at no time did she actually see either the tow plane or the glider on tow. Secondly; as I watched both aircraft slowly fly off to my right; I noted that I most likely would have never seen the tow plane as it was mostly off-white in color when viewed from above and it blended nicely with the ground clutter in the area. However; the glider was a combination of highly visible orange and yellow; which hopefully I would have seen had I been in a position to do so; I could not have seen either aircraft since they were approaching us from my blind side - below and left and climbing into us; my position in the cockpit was the right seat. Post flight discussion with the glider pilot (tow pilot was unavailable or would not take my call) revealed a 'this is our turf' attitude with regard to glider operations at this airport. The glider pilot stated several times that 'we are flying a pattern approved by the FAA.' this latter point seems to apparently be used by the tow operators as a shield from irresponsible action(s) on their part. Further discussion with the glider pilot proved insightful in regard to how tow operations are conducted: 1. The only call made by tow pilots is a 'glider on tow departing runway xx'. No other calls are made while in the pattern; according to this glider pilot. The reason stated by the glider pilot is that 'this airport is too busy to make standard traffic calls as it would clog the radio (CTAF frequency).'2. Tow operations are conducted in a cavalier manner. 3. Most glider pilots operating at the airport do not have radios and therefore cannot defuse a potential traffic conflict. Nor can they announce position and/or intentions. I do not absolve myself from scrutiny in the above event. 'See and avoid' was the order of the day; but did not work for me due to the previously stated fact that the other aircraft approached from my blind side. This did show that a proper lookout doctrine/discipline; especially applied when flying through such potentially busy airspace; might have caused my crew member to call out anything 'suspicious' when observed - this was my responsibility to reiterate to my crew. Also; I was not aware that such specific glider tow patterns were in place. I have personally briefed three pilots of this near midair and the circumstances surrounding it. In this instance; I unintentionally placed my aircraft; crew; and customer in exactly a location/flight path where the potential for a near midair was increased because it intersected with a published glider tow flight path/operation. All the pilots are acutely aware of the midair collision that occurred last year. The circumstances were very similar - a VFR aircraft transiting through the area collided with a tow plane (glider on tow).

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Original NASA ASRS Text

Title: A helicopter pilot at 6;800 FT had a near miss over BDU with a NORDO tow aircraft and radio equipped glider under tow only to find out that an established FAA tow pattern is approved in which pilots make no calls once airborne.

Narrative: CTAF frequency was monitored and appropriate calls were made north northwest of [the airport] at approximately 10 NM; 5 NM; 2 NM; and when 'overhead the numbers' of Runway 26. In addition to this being a nearly direct route to the destination; direct over flight of the airport was; in my mind; the safest route through the busy traffic area/corridor and nearby airports; the altitude being flown (6;800 FT MSL) was well above the traffic pattern. I heard several CTAF advisory calls made by airplanes in the vicinity: one was approaching from the east at about ten miles; one was entering a downwind for Runway 08; another had just landed and was taxiing for parking on the ramp. I was able to obtain a visual on the traffic except for the aircraft arriving from the east; however; I did 'see' all airborne traffic on my Traffic Awareness System (TAS) display. At no time did I visually observe or see any traffic on my TAS other than the participating aircraft making calls on the CTAF frequency. As I neared the approach end of Runway 26; I made a call of my position on the CTAF frequency with altitude. I was heading approximately 165 degrees. Within five seconds; I observed a tow plane with glider on tow pass below; left to right; and slightly ahead of my position on a westerly heading. Maneuver was not required; but in any case would have been too late if it had been necessary. At no time did I hear any called traffic indicating a tow plane with glider in the vicinity of the airport. There was no indication of such close proximity traffic on my TAS; and no 'traffic alert' was issued by my TAS; I concluded that no transponder was in use by the tow plane. I made a call on the CTAF frequency and asked 'if the tow plane was on the traffic advisory frequency.' No answer. I again made a call requesting a response from the tow plane. This time I received an answer from the pilot of the glider on tow. I asked the glider pilot if he had seen or heard my traffic calls; he said 'no'. I then asked UNICOM for tow plane info and I stated that I would call the tow operator at the conclusion of my flight (in about one hour). By this time I was approaching [airport] airspace and had to switch up that frequency in order to request transit through that airspace. After the glider on tow passed below and from left to right in front of us; I informed my crew about the near miss. The crew member; who was seated in the left rear forward facing seat; stated that she had seen 'two shadows; very closely spaced; on the ground off to our left'; but she didn't say anything because she was trying to 'figure out' what they were. However; at no time did she actually see either the tow plane or the glider on tow. Secondly; as I watched both aircraft slowly fly off to my right; I noted that I most likely would have never seen the tow plane as it was mostly off-white in color when viewed from above and it blended nicely with the ground clutter in the area. However; the glider was a combination of highly visible orange and yellow; which hopefully I would have seen had I been in a position to do so; I could not have seen either aircraft since they were approaching us from my blind side - below and left and climbing into us; my position in the cockpit was the right seat. Post flight discussion with the glider pilot (tow pilot was unavailable or would not take my call) revealed a 'this is our turf' attitude with regard to glider operations at this airport. The glider pilot stated several times that 'we are flying a pattern approved by the FAA.' This latter point seems to apparently be used by the tow operators as a shield from irresponsible action(s) on their part. Further discussion with the glider pilot proved insightful in regard to how tow operations are conducted: 1. The only call made by tow pilots is a 'glider on tow departing Runway XX'. No other calls are made while in the pattern; according to this glider pilot. The reason stated by the glider pilot is that 'this airport is too busy to make standard traffic calls as it would clog the radio (CTAF frequency).'2. Tow operations are conducted in a cavalier manner. 3. Most glider pilots operating at the airport do not have radios and therefore cannot defuse a potential traffic conflict. Nor can they announce position and/or intentions. I do not absolve myself from scrutiny in the above event. 'See and avoid' was the order of the day; but did not work for me due to the previously stated fact that the other aircraft approached from my blind side. This did show that a proper lookout doctrine/discipline; especially applied when flying through such potentially busy airspace; might have caused my crew member to call out anything 'suspicious' when observed - this was my responsibility to reiterate to my crew. Also; I was not aware that such specific glider tow patterns were in place. I have personally briefed three pilots of this near midair and the circumstances surrounding it. In this instance; I unintentionally placed my aircraft; crew; and customer in exactly a location/flight path where the potential for a near midair was increased because it intersected with a published glider tow flight path/operation. All the pilots are acutely aware of the midair collision that occurred last year. The circumstances were very similar - a VFR aircraft transiting through the area collided with a tow plane (glider on tow).

Data retrieved from NASA's ASRS site as of April 2012 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.