Narrative:

My student and I were in the traffic pattern at montgomery field airport. Weather was clear and visibility was great; it was a typical san diego morning with visual conditions everywhere. The tower controller was getting loaded with aircraft; and at the time of the incident there were 6 or 7 aircraft waiting to take off from our runway. There were also a number of aircraft coming in from the east to land or enter the traffic pattern. Congestion was apparent on the radio. The controller's voice did not sound panicked; but it seemed the controller was struggling to handle the number of aircraft on frequency.montgomery field has a crossing runway 5/23 in addition to the 10/28 parallels. Two helicopters were doing touch and go practice from the numbers of 23; remaining north of runway 28R at all times. Their pattern is below and well within the fixed wing pattern of 1;227 ft MSL for runway 28R.the incident helicopter is black or dark colored; difficult to see against the shadowed mountainous terrain in the local area. While on the crosswind with wings level; I had seen the incident helicopter and announced its position to my student. We then banked into the turn to downwind and I lost visual with the helicopter which was at low altitude. The tower controller came on frequency to announce the position of a helicopter at unknown altitude (due to a faulty mode C transponder signal) at our 12 or 1 o'clock position; estimating their altitude to be 1;000 ft MSL. I knew where to look based on my previous sighting of the traffic and located it at our altitude and in our 12 o'clock position. The helicopter also called us in sight to the tower. Immediately I realized that we needed to take evasive action because the helicopter had turned around and was now heading the wrong way on the downwind leg at our altitude and was on a direct collision course. We banked the airplane steeply to the left (north) and distanced ourselves from the runway.during this time the helicopter passed roughly 15 ft above us and off our right wing at a distance of less than 200 ft horizontally. I elected to end the lesson as both myself and my student were shaken by the event. After landing; I spoke with the tower chief and we discussed the situation. I believe there are a number of factors which led to the incident; including but not limited to: 1) poor communication between the tower and the incident helicopter regarding the helicopter's departure from the airport 2) poor communication between the tower and myself alerting me to the helicopter's planned departure from the airport 3) the faulty mode C information the tower received from the incident helicopter's transponder 4) the tower controller being stressed by a large volume of traffic at the time 5) temporary loss of situational awareness on the part of the incident helicopter pilot.given the early morning light; it would have been difficult to locate the incident helicopter if I had not made visual contact with it before entering the downwind leg of the traffic pattern. Had we not made the immediate decision to turn north away from the airport; the risk of mid-air collision would have been extremely high. Together; the actions of my student; myself; and the incident helicopter resulted in increased separation between the aircraft involved and everyone is alive to learn from the experience. Proper rest; proper attention; and proper reaction time on the part of myself and my student definitely contributed to the positive outcome of the situation.

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Original NASA ASRS Text

Title: C172 Instructor reported NMAC with a helicopter in the traffic pattern at MYF; citing Tower Controller workload as contributing.

Narrative: My student and I were in the traffic pattern at Montgomery Field Airport. Weather was clear and visibility was great; it was a typical San Diego morning with visual conditions everywhere. The Tower Controller was getting loaded with aircraft; and at the time of the incident there were 6 or 7 aircraft waiting to take off from our runway. There were also a number of aircraft coming in from the East to land or enter the traffic pattern. Congestion was apparent on the radio. The Controller's voice did not sound panicked; but it seemed the controller was struggling to handle the number of aircraft on frequency.Montgomery Field has a crossing Runway 5/23 in addition to the 10/28 parallels. Two helicopters were doing touch and go practice from the numbers of 23; remaining north of Runway 28R at all times. Their pattern is below and well within the fixed wing pattern of 1;227 FT MSL for Runway 28R.The incident helicopter is black or dark colored; difficult to see against the shadowed mountainous terrain in the local area. While on the crosswind with wings level; I had seen the incident helicopter and announced its position to my student. We then banked into the turn to downwind and I lost visual with the helicopter which was at low altitude. The Tower Controller came on frequency to announce the position of a helicopter at unknown altitude (due to a faulty Mode C transponder signal) at our 12 or 1 o'clock position; estimating their altitude to be 1;000 FT MSL. I knew where to look based on my previous sighting of the traffic and located it at our altitude and in our 12 o'clock position. The helicopter also called us in sight to the Tower. Immediately I realized that we needed to take evasive action because the helicopter had turned around and was now heading the wrong way on the downwind leg at our altitude and was on a direct collision course. We banked the airplane steeply to the left (north) and distanced ourselves from the runway.During this time the helicopter passed roughly 15 FT above us and off our right wing at a distance of less than 200 FT horizontally. I elected to end the lesson as both myself and my student were shaken by the event. After landing; I spoke with the Tower Chief and we discussed the situation. I believe there are a number of factors which led to the incident; including but not limited to: 1) Poor communication between the Tower and the incident helicopter regarding the helicopter's departure from the airport 2) Poor communication between the Tower and myself alerting me to the helicopter's planned departure from the airport 3) The faulty Mode C information the Tower received from the incident helicopter's transponder 4) The Tower Controller being stressed by a large volume of traffic at the time 5) Temporary loss of situational awareness on the part of the incident helicopter pilot.Given the early morning light; it would have been difficult to locate the incident helicopter if I had not made visual contact with it before entering the downwind leg of the traffic pattern. Had we not made the immediate decision to turn north away from the airport; the risk of mid-air collision would have been extremely high. Together; the actions of my student; myself; and the incident helicopter resulted in increased separation between the aircraft involved and everyone is alive to learn from the experience. Proper rest; proper attention; and proper reaction time on the part of myself and my student definitely contributed to the positive outcome of the situation.

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.