Narrative:

While on a training flight involving navigation problems at a planned altitude of 1300 ft and while traversing under the 1500 ft floor of class C airspace, an inadvertent increase in altitude to approximately 1700 ft with unauthorized entry into class C airspace was discovered. The problem was discovered when checking vertical clearance to a nearby obstruction (radio tower). An immediate reduction in altitude was made to 1400 ft after visually clearing the area below. No other traffic was observed. Steps that will be taken to prevent a reoccurrence include: 1) minimize solo training activities while traversing under the floor of any class C airspace. Distracting activities such as navigation problems may usually be performed at another less critical location. 2) limit activity under the floor of class C airspace to traversing via the most direct pre-planned route. 3) investigation into GPS moving map technology in order to positively pinpoint boundaries of controled airspace.

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Original NASA ASRS Text

Title: STUDENT PLT OF A CESSNA 172 INADVERTENTLY CLBED INTO CLASS C AIRSPACE WHILE FLYING UNDERNEATH OF IT DURING A SOLO TRAINING FLT.

Narrative: WHILE ON A TRAINING FLT INVOLVING NAV PROBS AT A PLANNED ALT OF 1300 FT AND WHILE TRAVERSING UNDER THE 1500 FT FLOOR OF CLASS C AIRSPACE, AN INADVERTENT INCREASE IN ALT TO APPROX 1700 FT WITH UNAUTH ENTRY INTO CLASS C AIRSPACE WAS DISCOVERED. THE PROB WAS DISCOVERED WHEN CHKING VERT CLRNC TO A NEARBY OBSTRUCTION (RADIO TWR). AN IMMEDIATE REDUCTION IN ALT WAS MADE TO 1400 FT AFTER VISUALLY CLRING THE AREA BELOW. NO OTHER TFC WAS OBSERVED. STEPS THAT WILL BE TAKEN TO PREVENT A REOCCURRENCE INCLUDE: 1) MINIMIZE SOLO TRAINING ACTIVITIES WHILE TRAVERSING UNDER THE FLOOR OF ANY CLASS C AIRSPACE. DISTRACTING ACTIVITIES SUCH AS NAV PROBS MAY USUALLY BE PERFORMED AT ANOTHER LESS CRITICAL LOCATION. 2) LIMIT ACTIVITY UNDER THE FLOOR OF CLASS C AIRSPACE TO TRAVERSING VIA THE MOST DIRECT PRE-PLANNED RTE. 3) INVESTIGATION INTO GPS MOVING MAP TECHNOLOGY IN ORDER TO POSITIVELY PINPOINT BOUNDARIES OF CTLED AIRSPACE.

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.