NEW YORK -- The head of the Federal Aviation Administration said Wednesday the agency has taken steps to avoid a repeat of the technology failure last month that briefly halted all flights nationwide, but he said he couldn't promise there won't be another breakdown.
Separately, acting FAA administrator Billy Nolen defended the safety of airline travel in the United States after recent incidents at John F. Kennedy Airport in New York, in Austin, Texas, and off the coast of Hawaii. Still, Nolen said, he is putting together a team of experts to review airline safety.
"We are experiencing the safest period in aviation history, but we do not take that for granted," Nolen said during testimony before the Senate Commerce Committee. "Recent events remind us that we cannot become complacent."
The committee's hearing was billed as an examination of the failure of an FAA system that provides safety alerts to pilots, but lawmakers were most animated when they quizzed Nolen on the recent flight scares.
The move follows two runway incidents that could have been catastrophic and a deep dive that brought one plane alarmingly close to slamming into the ocean.
"In the past few months there have been several incidents that could have cost a terrible loss of life," said Col Steve Ganyard, USMC (Ret.), ABC News Contributor.
A midair scare in December just recently came to light in which a United Airlines plane departing Maui took a nosedive. It plummeted more than 1,400 feet in about 20 seconds, coming within 775 feet of the Pacific Ocean.
Passengers say they "were praying for a miracle" while others were screaming. The pilots regained altitude and flew on to San Francisco.
United says the pilots are receiving additional training.
Another recent close call was at New York's JFK Airport.
A Delta plane nearly collided with an American Airlines flight that was crossing an active runway.
"This could have been the worst aviation disaster in U.S. history," Ganyard said.
The American Airlines pilots are now complying with subpoenas from the NTSB after they initially declined three requests to be interviewed as part of the investigation.
There is likely no cockpit recording from either of the American or United close calls. That's because both planes continued with their flight plans and the cockpit data recordings only last for two hours.
"If an airplane takes off and flies a long distance, it gets overwritten and data is lost," Ganyard said. "The FAA is pushing for longer 25-hour recorder so even if a plane is on longer flight, we'll be able to look at what went wrong and create steps from it happening again."
The FAA says the new safety review will "examine the U.S. aerospace system's structure, culture, and processes."
Most recently, the FAA and NTSB are investigating a close call involved a United Boeing 777 and a Cessna in Honolulu that came within 1,170 feet from each other when the 777 crossed the same runway where the Cessna was landing. The United plane crossed the runway without ATC clearance. FAA and NTSB statements below. United is referring all questions about the incident to the NTSB.
Nolen pointed out that the U.S. has not had a fatal crash involving an airline plane since 2009. Still, he said, he is forming an expert panel to review the aviation system and hold a safety summit next month to determine what steps are needed to maintain the record of recent years.
(The Associated Press contributed to this report.)