PALM SPRINGS, Calif. -

Investigators are still trying to determine what caused the crash of a vintage airplane during a stunt at a Northern California air show that killed a pilot. The NTSB will examine the wreckage and ground scars. 

"We're looking at the wreckage, the ground scars.," said NTSB Investigator, Howard Plagens. "That's the stuff we have to focus on today."

Sunday's show became the last of nearly 1,000 performances for stunt pilot, 77-year-old Edward Andreini. Andreini began flying as a teenager. The crash happened when something suddenly went wrong. 

"He was flying upside down, close to the ground," said Kent Thomas of Palm Springs Biplanes. "Flying close to the ground is of course more dangerous."

Thomas has been flying the same biplane for four years. It is the exact same make and model as the aircraft that Andreini was flying Sunday.

According to Thomas, crashes like Sunday's don't happen all the time. 

"You take people that are pushing themselves to the absolute peak of their performance abilities and they're driven to get better and better and more and more exciting," said Thomas. "So, I'd say the probability is good that something could happen at any air show, at any car race, motorcycle race."

Thomas says knowing your own capabilities is important, as well as staying within the perimeters of those capabilities. Andreini was a very experienced pilot, who flew for more than 60 years.

"The gentleman who dies in the plane crash was very qualified to do what he did, just in life something went wrong," concluded Thomas.