Narrative:

While departing the hospital on a patient flight; I made two radio calls; one on the helicopter air to air frequency and one on the CTAF for ZZZ airfield. At approximately 500 ft; I made another radio report on CTAF advising my location three miles southeast of the approach end of runway 25 and my intended route and altitude climbing to. No other traffic on the radio was heard. The tower was closed and class D was not in effect. I crossed ZZZ on a course to the medical center; approximately 315-320 degrees. I was climbing approximately through 5;500 ft for 6;500 ft when I saw a beech type airplane at my ten o'clock position closing rapidly; co-altitude. I immediately banked right but stopped the turn as I observed it passing to my 6 o'clock; and it passed behind my aircraft at approximately 200 ft or less. The airplane made no observed evasive maneuver and appeared to be straight and level. His course was approximately 080 degrees. I called on the radio for traffic at ZZZ and the pilot answered...stating he was downwind for runway 26 at ZZZ. I asked him if he had reported downwind; he stated; 'no' and that tower was closed. I asked him if he had heard my report; he stated no. He then stated his co-pilot did not hear it either. No further communication was exchanged. The remainder of the flight was uneventful.

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Original NASA ASRS Text

Title: AS-350 helicopter; climbing through the airspace of an airport whose Tower was closed; had a near miss with a Beech aircraft in the landing pattern. The helicopter pilot had called his position on CTAF; but the other aircraft had not transmitted his intentions.

Narrative: While departing the hospital on a patient flight; I made two radio calls; one on the helicopter air to air frequency and one on the CTAF for ZZZ Airfield. At approximately 500 FT; I made another radio report on CTAF advising my location three miles southeast of the approach end of Runway 25 and my intended route and altitude climbing to. No other traffic on the radio was heard. The Tower was closed and Class D was not in effect. I crossed ZZZ on a course to the medical center; approximately 315-320 degrees. I was climbing approximately through 5;500 FT for 6;500 FT when I saw a Beech type airplane at my ten o'clock position closing rapidly; co-altitude. I immediately banked right but stopped the turn as I observed it passing to my 6 o'clock; and it passed behind my aircraft at approximately 200 FT or less. The airplane made no observed evasive maneuver and appeared to be straight and level. His course was approximately 080 degrees. I called on the radio for traffic at ZZZ and the pilot answered...stating he was downwind for Runway 26 at ZZZ. I asked him if he had reported downwind; he stated; 'No' and that Tower was closed. I asked him if he had heard my report; he stated no. He then stated his co-pilot did not hear it either. No further communication was exchanged. The remainder of the flight was uneventful.

Data retrieved from NASA's ASRS site as of July 2013 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.