C172 instructor pilot reported near midair collision on approach to shn.

Narrative:

Student and I were flying a simulated engine out right traffic pattern to runway 5 at shn. The student did call his downwind; but not base or final. I heard a partial radio call from another aircraft during our approach; but it was not clear. I did not make any calls. On short final we were lined up for runway 5; about .4 miles out; all of a sudden; the student (left seat) saw the other aircraft on our left in front; which was apparently taking off from the opposite direction runway 23. The wind was from direction 120. We didn't hear their call for takeoff. Both planes banked right and narrowly avoided collision; with the other plane passing just under us (100-200 feet vertical). Even though we were lined up with the runway from about .75 nm out; and looking at the runway; on centerline; we did not see the other aircraft until the last second. What caused this incident is lack of sufficient radio calls in pattern while executing a simulated emergency. Also learned that teaching simulated emergencies near a non-towered airport requires extra vigilance from instructor in making sure that traffic calls are made and there is situational awareness of traffic around the airport. Do not assume other aircraft will use the same runway that the wind seems to be indicating. Always clear for opposite direction traffic in the pattern; especially on final.

Original NASA ASRS Text

Title: C172 instructor pilot reported NMAC on approach to SHN.

Narrative: Student and I were flying a simulated engine out right traffic pattern to runway 5 at SHN. The student did call his downwind; but not base or final. I heard a partial radio call from another aircraft during our approach; but it was not clear. I did not make any calls. On short final we were lined up for runway 5; about .4 miles out; all of a sudden; the student (left seat) saw the other aircraft on our left in front; which was apparently taking off from the opposite direction runway 23. The wind was from direction 120. We didn't hear their call for takeoff. Both planes banked right and narrowly avoided collision; with the other plane passing just under us (100-200 feet vertical). Even though we were lined up with the runway from about .75 nm out; and looking at the runway; on centerline; we did not see the other aircraft until the last second. What caused this incident is lack of sufficient radio calls in pattern while executing a simulated emergency. Also learned that teaching simulated emergencies near a non-towered airport requires extra vigilance from instructor in making sure that traffic calls are made and there is situational awareness of traffic around the airport. Do not assume other aircraft will use the same runway that the wind seems to be indicating. Always clear for opposite direction traffic in the pattern; especially on final.

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.

Attributes
ACN	1257410
Time
Date	201504
Local Time Of Day	1201-1800
Place
Locale Reference	SHN.Airport
State Reference	WA
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	VFR
Person 1
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 75 Flight Crew Total 1600 Flight Crew Type 1550
Events
Anomaly	Conflict NMAC Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 100 Vertical 150