Narrative:

Mmu cleared my plane (C172RG) (with private pilot on practice flight) to depart runway 5, maintain 1300 ft, before on course, turn northwest. No other aircraft communications were heard. However, mmu tower, on our takeoff roll, advised another aircraft that the active was going to be changed. At 1100 ft, while climbing straight-out prior to left turn, I saw a gulfstream at my immediate 11 O'clock position, on a right base to final in a severe short approach. It was difficult at first to determine proper evasive action, but I determined an immediate left climbing turn. The gulfstream was within 100 yards. Upon querying tower, gulfstream pilot came back with 'if you had mode C on, we would have seen you.' we had proper mode C on. The gulfstream never looked. Tower had no comment. The gulfstream wasn't on 118.1 when I departed, or at least I never heard his communication with tower. The gulfstream made an inordinately short approach without looking outside the plane -- as is his responsibility. Callback conversation with reporter revealed the following information: the reporter stated that the initial tower clearance to climb to 1300 ft before starting a turn was unusual, but no reason was given. While he heard the tower advise someone that a change in active runway was forthcoming, he never heard the gulfstream iv on the frequency. The reporter took control of the aircraft to make the evasive maneuver when the traffic was sighted. He also indicated that the gulfstream iv flight crew did not have his aircraft north sight until the last min due to their comment regarding having the mode C on. The reporter is quite familiar with the operation at mmu and stated that the traffic pattern altitude for jet traffic is 1500 ft, suggesting that the gulfstream iv should have been above him had they been flying a normal pattern.

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Original NASA ASRS Text

Title: C172 CFI AND STUDENT AVOID NMAC WITH GULFSTREAM IV DEPARTING MMU.

Narrative: MMU CLRED MY PLANE (C172RG) (WITH PVT PLT ON PRACTICE FLT) TO DEPART RWY 5, MAINTAIN 1300 FT, BEFORE ON COURSE, TURN NW. NO OTHER ACFT COMS WERE HEARD. HOWEVER, MMU TWR, ON OUR TKOF ROLL, ADVISED ANOTHER ACFT THAT THE ACTIVE WAS GOING TO BE CHANGED. AT 1100 FT, WHILE CLBING STRAIGHT-OUT PRIOR TO L TURN, I SAW A GULFSTREAM AT MY IMMEDIATE 11 O'CLOCK POS, ON A R BASE TO FINAL IN A SEVERE SHORT APCH. IT WAS DIFFICULT AT FIRST TO DETERMINE PROPER EVASIVE ACTION, BUT I DETERMINED AN IMMEDIATE L CLBING TURN. THE GULFSTREAM WAS WITHIN 100 YARDS. UPON QUERYING TWR, GULFSTREAM PLT CAME BACK WITH 'IF YOU HAD MODE C ON, WE WOULD HAVE SEEN YOU.' WE HAD PROPER MODE C ON. THE GULFSTREAM NEVER LOOKED. TWR HAD NO COMMENT. THE GULFSTREAM WASN'T ON 118.1 WHEN I DEPARTED, OR AT LEAST I NEVER HEARD HIS COM WITH TWR. THE GULFSTREAM MADE AN INORDINATELY SHORT APCH WITHOUT LOOKING OUTSIDE THE PLANE -- AS IS HIS RESPONSIBILITY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THE INITIAL TWR CLRNC TO CLB TO 1300 FT BEFORE STARTING A TURN WAS UNUSUAL, BUT NO REASON WAS GIVEN. WHILE HE HEARD THE TWR ADVISE SOMEONE THAT A CHANGE IN ACTIVE RWY WAS FORTHCOMING, HE NEVER HEARD THE GULFSTREAM IV ON THE FREQ. THE RPTR TOOK CTL OF THE ACFT TO MAKE THE EVASIVE MANEUVER WHEN THE TFC WAS SIGHTED. HE ALSO INDICATED THAT THE GULFSTREAM IV FLC DID NOT HAVE HIS ACFT N SIGHT UNTIL THE LAST MIN DUE TO THEIR COMMENT REGARDING HAVING THE MODE C ON. THE RPTR IS QUITE FAMILIAR WITH THE OP AT MMU AND STATED THAT THE TFC PATTERN ALT FOR JET TFC IS 1500 FT, SUGGESTING THAT THE GULFSTREAM IV SHOULD HAVE BEEN ABOVE HIM HAD THEY BEEN FLYING A NORMAL PATTERN.

Data retrieved from NASA's ASRS site as of July 2007 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.