Narrative:

I was departing whp runway 12; right downwind; and at pattern altitude. Tower handed me off to socal early (still in class D; or at least very close to it) and I requested flight following and had received a squawk code; still very close to the airport; if not in whp class D at pattern altitude (level at 2;000 feet; since 3;000 feet is the bur class C).a few seconds after receiving the code; a helicopter; climbing fast and at same altitude; appeared on a direct collision path with my plane. We saw each other; turned abruptly; and avoided a collision.I informed ATC of my abrupt turn and near-encounter with what appeared to be a helicopter. ATC confirmed radar contact with both planes and apologized. They said the target was flying low under radar; climbed quickly; and then dove down low again after the near miss.importantly; ATC said they saw him on radar suddenly; but he was so close to me that we merged into one image on the radar screen. He did not know there were two aircraft until I reported the near-miss.ATC was not talking to the helicopter. ATC offered to try to track down the helicopter; since he was near or in class D space; not talking to anyone; and in and out of radar. ATC called kwhp; kbur and kvny and no one could identify the helicopter.while I was able to see and avoid; this reiterates what instructors have long told me; don't assume anyone has your back; even in controlled; busy airspace. Don't assume other pilots use flight following. Keep your eyes out the window. If I hadn't had my eyes outside the window; this situation could have had a very different outcome.

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Original NASA ASRS Text

Title: General aviation pilot reported an NMAC with a helicopter in WHP Class D while receiving flight following from SCT. Evasive action was taken by both pilots to avoid collision.

Narrative: I was departing WHP Runway 12; right downwind; and at pattern altitude. Tower handed me off to SoCal early (still in Class D; or at least very close to it) and I requested flight following and had received a squawk code; still very close to the airport; if not in WHP Class D at pattern altitude (level at 2;000 feet; since 3;000 feet is the BUR Class C).A few seconds after receiving the code; a helicopter; climbing fast and at same altitude; appeared on a direct collision path with my plane. We saw each other; turned abruptly; and avoided a collision.I informed ATC of my abrupt turn and near-encounter with what appeared to be a helicopter. ATC confirmed radar contact with both planes and apologized. They said the target was flying low under radar; climbed quickly; and then dove down low again after the near miss.Importantly; ATC said they saw him on radar suddenly; but he was so close to me that we merged into one image on the radar screen. He did not know there were two aircraft until I reported the near-miss.ATC was not talking to the helicopter. ATC offered to try to track down the helicopter; since he was near or in Class D space; not talking to anyone; and in and out of radar. ATC called KWHP; KBUR and KVNY and no one could identify the helicopter.While I was able to see and avoid; this reiterates what instructors have long told me; don't assume anyone has your back; even in controlled; busy airspace. Don't assume other pilots use flight following. Keep your eyes out the window. If I hadn't had my eyes outside the window; this situation could have had a very different outcome.

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.