During visual approach to slc; pilot misunderstood tower instructions and descends to 5500 ft causin...

Attributes
ACN	850808
Time
Date	200909
Local Time Of Day	0601-1200
Place
Locale Reference	SLC.Airport
State Reference	UT
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Flight Plan	VFR
Aircraft 2
Make Model Name	Small Aircraft
Flight Phase	Initial Climb
Person 1
Function	Single Pilot
Qualification	Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 76 Flight Crew Total 4575
Events
Anomaly	Conflict NMAC Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance
Miss Distance	Horizontal 0 Vertical 300

Narrative:

I had been in contact with approach control; 6500 ft over I-15. Transferred to tower. Tower gave instructions to fly downwind over redwood road (I thought he said @ 5500). I answered back 'descending to 5500; downwind over redwood road.' I started to descend to 5500. I noticed; out the left pilot's window; a white single engine airplane that crossed beneath me in an easterly direction. (I was flying south). Controller told me to climb to 6500 and then turn east toward I-15; then north along I-15. Then asked why I had descended. He said his instructions were to maintain 6500 over redwood road. Then I was cleared again over redwood road at 6500; advised of landing traffic and then cleared to land after that traffic. I think it was just a miscommunication; I perceived that he wanted me to descend; he felt he had instructed me to maintain altitude. This experience will make me more cautious; and make sure I understand instructions and communications.

Original NASA ASRS Text

Title: During visual approach to SLC; pilot misunderstood tower instructions and descends to 5500 FT causing a NMAC. Reporter is cleared back to 6500 FT and vectored back around for a visual landing.

Narrative: I had been in contact with Approach Control; 6500 FT over I-15. Transferred to Tower. Tower gave instructions to fly downwind over Redwood Road (I thought he said @ 5500). I answered back 'Descending to 5500; Downwind over Redwood Road.' I started to descend to 5500. I noticed; out the left pilot's window; a white single engine airplane that crossed beneath me in an easterly direction. (I was flying south). Controller told me to climb to 6500 and then turn east toward I-15; then north along I-15. Then asked why I had descended. He said his instructions were to maintain 6500 over Redwood Road. Then I was cleared again over Redwood Road at 6500; advised of landing traffic and then cleared to land after that traffic. I think it was just a miscommunication; I perceived that he wanted me to descend; he felt he had instructed me to maintain altitude. This experience will make me more cautious; and make sure I understand instructions and communications.

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.

During visual approach to slc; pilot misunderstood tower instructions and descends to 5500 ft causing a near midair collision. Reporter is cleared back to 6500 ft and vectored back around for a visual landing.