Skyhawk 172/Cutlass 172
Flight Crew Private
Flight Crew Last 90 Days 40; Flight Crew Total 290; Flight Crew Type 40
Situational Awareness; Other / Unknown
Aircraft Equipment Problem Less Severe
Flight Crew Took Evasive Action
Aircraft; Weather; Human Factors
I had forgotten my GPS NAV cards after bringing them home to update; but had an iPad for current charts. I was heading south along the coast. I was watching the coastline for distance and clearance from the SNA [Charlie] airspace. [Because of] the haze around me I realized I felt too close to the shore. The iPad said it had lost the GPS signal. I immediately descended and turned away from shore fearing I was inside the [Charlie] airspace. I switched my radio to the guard frequency (121.5) and listened; but did not broadcast. I heard nothing. I believe the haze contributed since I was focusing on the immediate space around me and watching for traffic versus head in cockpit watching the iPad. I continued south for the flight and eventually turned to CRQ. On the return I made very sure I had plenty of space to land. I almost went all the way to Catalina (SXC) and then turned towards TOA. I landed without incident. I have two GPS units onboard and the iPad is the backup. I learned to only update one GPS at a time and I added an item to my checklist to confirm I have at least one operational GPS. I am not sure I violated the SNA [Charlie] airspace as I had no DME and did not trust the iPad but felt I should file this report in case. The distance and radials are approximate.
C172 pilot reports a possible Class C incursion due to loss of GPS signal to his iPad at 3;000 FT south of SNA.