PG&E told the NTSB that it has enhanced communications with first responders and customers, but that has been since the September explosion. The NTSB is also interested in the situation before then.
Haag told the NTBS he thought small gas distribution lines to individual homes were all he had to worry about.
"We did not know that there was a transmission line through the city until after the incident," said Haag.
Line 132, a 30-inch natural gas pipeline, ran through a densely populated neighborhood, but the residents didn't know either.
"In my conversations with the residents, they had no idea they were on a pipeline," said Haag.
Yet there are regulations requiring utilities to inform first responders and warn residents.
"But the fire chief just said a few minutes ago that prior to September 9, he really wasn't aware of Line 132. So, how do you explain that?" asked a NTSB board member.
Aaron Rezendez from PG&E said, "I can't."
And the NTSB pointed to a June 2010 third-party audit of the effectiveness of PG&E's safety awareness mailers. Fifteen-thousand postcards were sent out to customers living near pipelines. Only 20 responded and of those, only half realized they lived near a transmission line.
"I think even the 20 people who did respond demonstrates you've got serious problems with people being aware of what's going on around them," said NTSB Chairman Deborah A.P. Hersman.
The NTSB says public awareness is important for accident prevention by, for example, educating people how to recognize a leak and what to do if they think there is one.
Carl Weimer is executive director of the Pipeline Safety Trust -- the nation's only non-profit devoted to pipeline safety. He told the NTSB that there's a conflict of interest when the industry is also the messenger.
"If you look through the PG&E brochure, the first things you run into is 'Safe, efficient, reliable, the popular choice, the safest choice, the safety commitment.' You go through all those kinds of things telling you things are good before you get to the safety messages," said Weimer.
"What we need to do is tell people if they live within 2,000 feet of a transmission line, and then provide the additional awareness and education," said Rep. Jackie Speier, D-San Mateo.
The NTSB acknowledges that public education is very hard to do well. Thursday's panel focuses on industry technology including remote and automatic shut off valves.