Poor CTAF compliance at a non-towered airport contributed to an near midair collision for the report...

Attributes
ACN	977213
Time
Date	201110
Local Time Of Day	1201-1800
Place
Locale Reference	DMW.Airport
State Reference	MD
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Experimental
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	None
Aircraft 2
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Flight Phase	Descent
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 10 Flight Crew Total 1200 Flight Crew Type 560
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 250 Vertical 100

Narrative:

While cruising at 2;750 MSL VFR my route was to take me directly over dmw which is at 789 ft MSL. I began monitoring CTAF frequency 20 miles out; heard one call when approx 15 miles out for an aircraft downwind to land. No other calls heard. Transmitted at 10 and 5 miles out that I would overfly dmw at 2;750; which is 1;000 ft above pattern altitude while traveling east to west. [I] called again when directly over the field's north-south runway. A twin then flew directly in front of my plane; apparently joining a right downwind to runway 16; missing my plane by approximately 250 ft horizontally and approximately 100 ft below vertically. The aircraft never made any calls on CTAF. My pcas did not alert to this twin aircraft.

Original NASA ASRS Text

Title: Poor CTAF compliance at a non-towered airport contributed to an NMAC for the reporter's homebuilt and a light twin whose pilot failed to make position and intention reports.

Narrative: While cruising at 2;750 MSL VFR my route was to take me directly over DMW which is at 789 FT MSL. I began monitoring CTAF frequency 20 miles out; heard one call when approx 15 miles out for an aircraft downwind to land. No other calls heard. Transmitted at 10 and 5 miles out that I would overfly DMW at 2;750; which is 1;000 FT above pattern altitude while traveling east to west. [I] called again when directly over the field's north-south runway. A twin then flew directly in front of my plane; apparently joining a right downwind to Runway 16; missing my plane by approximately 250 FT horizontally and approximately 100 FT below vertically. The aircraft never made any calls on CTAF. My PCAS did not alert to this twin aircraft.

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.

Poor CTAF compliance at a non-towered airport contributed to an near midair collision for the reporter's homebuilt and a light twin whose pilot failed to make position and intention reports.