Narrative:

I was instructing a pilot who was conducting a practice oak RNAV Y 27L approach. The pilot was wearing a view-limiting device and we had been handed off to oakland tower from norcal a few minutes earlier. The GPS in the aircraft did not have vertical guidance capability. I was coaching the pilot on how to manage the aircraft configuration and speed while complying with the crossing altitudes. He had been maintaining 110 KTS indicated during the descent on the approach. Descending through about 2;400 ft the tower pointed out a cessna at 10 to 11 o-clock at 2;000; same direction of flight. I reported the traffic in sight. The tower informed the other cessna of our location and the pilot reported us in sight. As we continued to descend; it was clear we were on converging courses and our altitudes would merge. I was considering how to best resolve this when the other pilot asked the tower how he should cross the final approach paths for 27L and 27R. The tower instructed him to pass behind us. I saw the other cessna enter a bank; but the haze made it hard to see. I initially assumed he was banking left to do a 360 degree turn; given our close proximity. After a few seconds; I realized he was banking right toward us as our altitudes were converging. Since we were approaching the final approach fix; the pilot I was instructing reduced power and configured flap 10 to begin slowing to 90 KTS; per our SOP. I announced I had the flight controls; added full power and pitched for a maximum performance climb as the other cessna passed underneath us. Looking behind us; I saw the other aircraft was now at our 5 to 6 o'clock and still quite close. As our paths diverged; I returned control to the pilot I was instructing and he resumed the practice approach. I asked the tower for the cessna's tail number because I thought I recognized it and wanted to contact the owner/operator. The tower told me to ask ground after landing. Ground told us to call the tower and I did. The manager on duty said he couldn't tell me the tail number. I told the manager on duty that had the tower controller simply told the other cessna to make a left 360; the conflict would have been avoided. In the past; the oak tower controllers have given more explicit instructions to resolve conflicts between traffic watch aircraft that frequently transition oakland's airspace and other aircraft. I had assumed that with one aircraft conducting a practice approach; tower would have provided more explicit and timely separation. My impression was that the tower controller was a developmental controller or had not been working at oakland for very long. I suspect he assumed that it was enough for two aircraft to have each other in sight. Contributing factors were the haze and the other aircraft being a high-wing aircraft with limited visibility.

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Original NASA ASRS Text

Title: C172 Instructor reports a NMAC with another C172 during a practice approach to Runway 27L at OAK. Each pilot had the other in sight and the Tower Controller had them on Radar.

Narrative: I was instructing a pilot who was conducting a practice OAK RNAV Y 27L approach. The pilot was wearing a view-limiting device and we had been handed off to Oakland Tower from NORCAL a few minutes earlier. The GPS in the aircraft did not have vertical guidance capability. I was coaching the pilot on how to manage the aircraft configuration and speed while complying with the crossing altitudes. He had been maintaining 110 KTS indicated during the descent on the approach. Descending through about 2;400 FT the Tower pointed out a Cessna at 10 to 11 o-clock at 2;000; same direction of flight. I reported the traffic in sight. The Tower informed the other Cessna of our location and the pilot reported us in sight. As we continued to descend; it was clear we were on converging courses and our altitudes would merge. I was considering how to best resolve this when the other pilot asked the Tower how he should cross the final approach paths for 27L and 27R. The Tower instructed him to pass behind us. I saw the other Cessna enter a bank; but the haze made it hard to see. I initially assumed he was banking left to do a 360 degree turn; given our close proximity. After a few seconds; I realized he was banking right toward us as our altitudes were converging. Since we were approaching the final approach fix; the pilot I was instructing reduced power and configured flap 10 to begin slowing to 90 KTS; per our SOP. I announced I had the flight controls; added full power and pitched for a maximum performance climb as the other Cessna passed underneath us. Looking behind us; I saw the other aircraft was now at our 5 to 6 o'clock and still quite close. As our paths diverged; I returned control to the pilot I was instructing and he resumed the practice approach. I asked the Tower for the Cessna's tail number because I thought I recognized it and wanted to contact the owner/operator. The Tower told me to ask Ground after landing. Ground told us to call the Tower and I did. The manager on duty said he couldn't tell me the tail number. I told the manager on duty that had the Tower Controller simply told the other Cessna to make a LEFT 360; the conflict would have been avoided. In the past; the OAK Tower controllers have given more explicit instructions to resolve conflicts between traffic watch aircraft that frequently transition Oakland's airspace and other aircraft. I had assumed that with one aircraft conducting a practice approach; Tower would have provided more explicit and timely separation. My impression was that the Tower Controller was a Developmental Controller or had not been working at Oakland for very long. I suspect he assumed that it was enough for two aircraft to have each other in sight. Contributing factors were the haze and the other aircraft being a high-wing aircraft with limited visibility.

Data retrieved from NASA's ASRS site as of July 2013 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.