Sailplane pilot reported a near mid air collision with an air carrier flight near boulder colorado.

Attributes
ACN	1556210
Time
Date	201806
Local Time Of Day	0601-1200
Place
Locale Reference	BJC.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Sail Plane
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	None
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Climb
Route In Use	SID FOOOT 3
Flight Plan	IFR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 80 Flight Crew Total 4000 Flight Crew Type 400
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 400 Vertical 200

Narrative:

While on a commercial sightseeing ride in a 2 seat glider from boulder I had a near miss with what looked like a large dual rear engine aircraft. It happened on the extended center line of the bjc runway 30 about 7 miles on the 300 radial. I had just alerted my ride passenger about the nearby bjc airport and encouraged him to help me spot for aircraft. I saw the jet heading straight for us at our 11 o clock and slightly below. I made a negative 1 G push over dive and turned away and I could see the jet continuing on its original heading. No sign that they had seen me or had taken any evasive action. I was in an all metal 2 to 3 seat glider that is not transponder equipped nor is it required to have a transponder. I spoke with the tower supervisor at bjc later that day and she shared with me that the plane we saw was a [commercial flight inbound] to slc.

Original NASA ASRS Text

Title: Sailplane pilot reported a near mid air collision with an air carrier flight near Boulder Colorado.

Narrative: While on a commercial sightseeing ride in a 2 seat glider from Boulder I had a near miss with what looked like a large dual rear engine aircraft. It happened on the extended center line of the BJC Runway 30 about 7 miles on the 300 radial. I had just alerted my ride passenger about the nearby BJC airport and encouraged him to help me spot for aircraft. I saw the jet heading straight for us at our 11 o clock and slightly below. I made a negative 1 G push over dive and turned away and I could see the jet continuing on its original heading. No sign that they had seen me or had taken any evasive action. I was in an all metal 2 to 3 seat glider that is not transponder equipped nor is it required to have a transponder. I spoke with the tower supervisor at BJC later that day and she shared with me that the plane we saw was a [commercial flight inbound] to SLC.

Data retrieved from NASA's ASRS site 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.