C172 entering traffic pattern at emt experienced near midair collision with a departing aircraft.

Attributes
ACN	610820
Time
Date	200403
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : emt.airport
State Reference	CA
Altitude	msl single value : 1300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : emt.tower
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : approach
Route In Use	approach : traffic pattern
Flight Plan	None
Aircraft 2
Controlling Facilities	tower : emt.tower
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	climbout : initial
Route In Use	approach : traffic pattern
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 43.9 flight time total : 259 flight time type : 200
ASRS Report	610820
Person 2
Function	flight crew : single pilot oversight : pic
Events
Anomaly	conflict : nmac non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	controller : issued advisory controller : issued new clearance flight crew : took evasive action
Miss Distance	horizontal : 60 vertical : 20
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

Check-in with emt tower (my home base) inbound landing 6 mi out. Tower requested me to report left downwind mid-field. Afterward, tower was busy to clear bunch of takeoff requests. One of them was cleared for the left downwind departure (I guess, did not pay attention to the detail). Tower did not provide the takeoff aircraft and me the traffic information. The near midair collision occurred on the corner of left crosswind/downwind corner. Both pilots got the traffic at the last moment. Both aircraft did a minor adjustment (stop climb and turn, stop descent/minor left turn) to avoid each other. 5 seconds after the conflict, another controller jumped in to amend the conflict TA, but it was over already. The near midair collision could have been avoided if I did a non solicited position report when I was about to enter the left downwind, instead of following the controller's instructions to report left downwind mid-field. I could do that because I was aware that there were many departures ahead of my arrival. But the departure aircraft switch to tower frequency right before takeoff, they have no idea about the inbound traffic if controller does not tell them.

Original NASA ASRS Text

Title: C172 ENTERING TFC PATTERN AT EMT EXPERIENCED NMAC WITH A DEPARTING ACFT.

Narrative: CHK-IN WITH EMT TWR (MY HOME BASE) INBOUND LNDG 6 MI OUT. TWR REQUESTED ME TO RPT L DOWNWIND MID-FIELD. AFTERWARD, TWR WAS BUSY TO CLR BUNCH OF TKOF REQUESTS. ONE OF THEM WAS CLRED FOR THE L DOWNWIND DEP (I GUESS, DID NOT PAY ATTN TO THE DETAIL). TWR DID NOT PROVIDE THE TKOF ACFT AND ME THE TFC INFO. THE NMAC OCCURRED ON THE CORNER OF L XWIND/DOWNWIND CORNER. BOTH PLTS GOT THE TFC AT THE LAST MOMENT. BOTH ACFT DID A MINOR ADJUSTMENT (STOP CLB AND TURN, STOP DSCNT/MINOR L TURN) TO AVOID EACH OTHER. 5 SECONDS AFTER THE CONFLICT, ANOTHER CTLR JUMPED IN TO AMEND THE CONFLICT TA, BUT IT WAS OVER ALREADY. THE NMAC COULD HAVE BEEN AVOIDED IF I DID A NON SOLICITED POS RPT WHEN I WAS ABOUT TO ENTER THE L DOWNWIND, INSTEAD OF FOLLOWING THE CTLR'S INSTRUCTIONS TO RPT L DOWNWIND MID-FIELD. I COULD DO THAT BECAUSE I WAS AWARE THAT THERE WERE MANY DEPS AHEAD OF MY ARR. BUT THE DEP ACFT SWITCH TO TWR FREQ RIGHT BEFORE TKOF, THEY HAVE NO IDEA ABOUT THE INBOUND TFC IF CTLR DOES NOT TELL THEM.

Data retrieved from NASA's ASRS site as of July 2007 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.