Narrative:

During a local training flight in VMC; we had been participating in flight following with joshua approach and were squawking a discrete transponder code. After completing several training maneuvers; at approximately 13 miles northwest of wjf; we advised joshua approach that we were proceeding to william J. Fox field for some touch and go's with information alpha; and they acknowledged. We began a descent from 4500 ft MSL to traffic pattern altitude and completed the descent checklist. At this point; we were inbound to the airport on a 45 entry for runway 24. At approximately 5 DME (GPS) from the airport; still squawking our assigned code; joshua had not yet told us to contact the tower; so we requested the switch. Joshua simply advised us to contact the tower. The trainee changed frequencies and attempted to contact fox tower; and when we received no reply; I noticed that she had set the frequency incorrectly. She then set the correct frequency and contacted the tower. At that time; our DME read 3.2 miles from the airport. As tower was responding to her contact to verify our position; the TCAS system alerted us to traffic at 12:00; same altitude; one mile. As we did not have the traffic in sight; we executed a climbing left turn to avoid the downwind leg. The tower then instructed us to make right traffic for runway 24 and we re-entered the pattern. After several touch and go's; we made a full stop and taxied back to runway 24. I contacted ground and explained the sequence of events during our arrival and asked for their advice. When the controller learned that we were with joshua on flight following; he explained that; unlike IFR; VFR aircraft must avoid class delta airspace until contact with the tower has been established. Having done much of my flying and instructing in and around class charlie airspace; I had incorrectly assumed that; since we were in contact with approach control and on a discrete transponder code; we were legal to enter class delta airspace. I now understand the difference between IFR and VFR arrival procedures; and will be sure to ask for the change to tower frequency at a distance that will allow for the switch before the airspace is encountered.

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Original NASA ASRS Text

Title: An Instructor reported entering Class D airspace before contacting Tower after TRACON VFR flight following. The Tower Controller counseled the pilot about who is responsible for Tower communications while VFR.

Narrative: During a local training flight in VMC; we had been participating in flight following with Joshua Approach and were squawking a discrete transponder code. After completing several training maneuvers; at approximately 13 miles northwest of WJF; we advised Joshua Approach that we were proceeding to William J. Fox Field for some touch and go's with information Alpha; and they acknowledged. We began a descent from 4500 FT MSL to traffic pattern altitude and completed the descent checklist. At this point; we were inbound to the airport on a 45 entry for Runway 24. At approximately 5 DME (GPS) from the airport; still squawking our assigned code; Joshua had not yet told us to contact the Tower; so we requested the switch. Joshua simply advised us to contact the Tower. The trainee changed frequencies and attempted to contact Fox Tower; and when we received no reply; I noticed that she had set the frequency incorrectly. She then set the correct frequency and contacted the Tower. At that time; our DME read 3.2 miles from the airport. As Tower was responding to her contact to verify our position; the TCAS system alerted us to traffic at 12:00; same altitude; one mile. As we did not have the traffic in sight; we executed a climbing left turn to avoid the downwind leg. The Tower then instructed us to make right traffic for Runway 24 and we re-entered the pattern. After several touch and go's; we made a full stop and taxied back to Runway 24. I contacted Ground and explained the sequence of events during our arrival and asked for their advice. When the Controller learned that we were with Joshua on flight following; he explained that; unlike IFR; VFR aircraft must avoid Class Delta airspace until contact with the Tower has been established. Having done much of my flying and instructing in and around Class Charlie airspace; I had incorrectly assumed that; since we were in contact with Approach Control and on a discrete transponder code; we were legal to enter Class Delta airspace. I now understand the difference between IFR and VFR arrival procedures; and will be sure to ask for the change to Tower frequency at a distance that will allow for the switch before the airspace is encountered.

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.