WASHINGTON – There’s a tragic parallel between Saturday’s crash-landing of a jetliner in San Francisco and the 2009 crash of Continental Connection Flight 3407 in Clarence Center.

In both accidents – and at least three other major aviation accidents in the last 11 years – it seems the pilots somehow didn’t notice that the plane was slowing, dangerously and fatally, toward an aerodynamic stall.

“Obviously the effect is the same: letting the airspeed get too slow, and there’s an accident as a result of it,” said Jeffrey B. Skiles, co-pilot on the USAir flight that landed safety on the Hudson River after a bird strike in 2009.

Aviation safety experts were left to ponder that parallel Monday as the National Transportation Safety Board reported that Asiana Airlines Flight 214 was traveling nearly 40 mph slower than it should have been, thereby scraping a sea wall and crash-landing at San Francisco International Airport.

While there are obviously huge differences between the crash of a foreign airline’s jumbo jet and the crash of a small regional commuter plane in a Buffalo suburb, it appeared Monday that pilot error was involved in San Francisco, just as it was in Clarence.

And that, aviation safety advocates and lawmakers said, makes the accident in San Francisco yet another argument for the pending pilot-training improvements mandated under law in the wake of the Flight 3407 crash, which claimed 50 lives.

Two people died in the San Francisco crash and several remained hospitalized as of Monday, but 305 people – including the four pilots – survived.

Briefing the media on the crash, National Transportation Safety Board Chairwoman Deborah A.P. Hersman said Monday that the agency is in the midst of a comprehensive investigation, including interviews with the four pilots.

While Hersman said the investigation is far from reaching a definitive conclusion, some things are already clear. Most notably, 3 seconds before impact, Flight 214 was traveling at 103 knots, or 118.5 mph, far short of a safe speed.

“One hundred and thirty-seven knots is the speed they want to have when they cross the threshold of the runway,” Hersman said. That would equal more than 157 mph.

Similarly, the target speed for Flight 3407, as it approached Buffalo Niagara International Airport, was 138 knots. But the NTSB found that the crew allowed the plane to slow to 131 knots, prompting the “stick shaker,” part of the stall-warning system, to activate.

But there are also some key differences between what happened in San Francisco on Saturday and in Clarence in 2009.

The pilots of Asiana Flight 214 allowed the plane to get dangerously slow at an altitude of 500 feet, just 34 seconds before the crash. Hersman said. And before that plane crashed, the pilots appeared to react correctly to the stick shaker stall warning by trying, unsuccessfully, to abort the landing by speeding up the plane.

In contrast, on Flight 3407, the stall warning sounded when the plane was at an altitude of 2,280 feet. And the plane crashed not because it was too late for the pilot to speed up and right the plane’s course, but because the pilot, Capt. Marvin D. Renslow, did exactly the opposite of what he should have done in reaction to the stall warning, the NTSB found.

In addition, the reasons the Asiana plane got dangerously slow are probably different from the ones that set Flight 3407 on its fatal course, Skiles said.

Yet the common element – pilots who endanger passengers by letting a plane decelerate too much and too quickly – seems all too common during an era that’s otherwise the safest ever for air travel.

For example, in addition to the San Francisco and Clarence crashes:

• In 2002, Sen. Paul D. Wellstone, D-Minn., and seven others died in a Minnesota small-plane crash that the NTSB blamed on “the flight crew’s failure to maintain adequate airspeed.”

• On Feb. 25, 2009, a Turkish Airlines jet crashed on landing in Amsterdam, claiming nine lives in an accident that investigators blamed on low airspeed.

• On June 1, 2009, Air France Flight 447 from Rio de Janeiro to Paris plummeted into the Atlantic, claiming 228 lives, and investigators said it happened because the crew let the plane fly too slowly and didn’t know how to recover from the ensuing stall.

While aviation safety experts stop short of saying that five such accidents make a trend, Skiles said that the string of pilot errors may be connected to an overreliance on technology in the cockpit and the ensuing deterioration of actual piloting skills – a problem The Buffalo News detailed in a 2009 series called “Who’s Flying Your Airplane?”

“It is true that by the use of automated systems, you tend to rely on them over time,” Skiles said. “And sometimes that can be a detriment to the overall operation.”

Another possible connection, at least between the San Francisco accident and the one in Clarence, involves pilot experience. Lee Gang-guk, the pilot of Asiana Flight 214, was a veteran pilot – but he had just 43 hours of flight time in the Boeing 777, just as Renslow was new to the Bombardier Dash 8 Q400, the type of plane that crashed in Clarence. Even so, aviation safety experts said the Korean pilot should have been able to handle a clear-weather daytime landing in San Francisco with no problem.

“This is really mystifying to me, though, how a highly experienced captain, even if not highly experienced in this particular airplane, let his speed deteriorate so much,” said Dan Morgan, former vice president of safety and compliance at Colgan Air, which operated Flight 3407.

One possible answer to that mystery involves pilot training, which is why Karen Eckert, one of the leaders of the Families of Continental Flight 3407, said it’s important that the Federal Aviation Administration finish new pilot training and experience regulations that Congress ordered in the wake of the Clarence crash.

“The things we have been fighting for – raising pilot qualifications, more robust and recurrent training, safety management systems and reducing pilot fatigue – are all focused on reducing pilot error and saving lives,” said Eckert, sister of 9/11 activist Beverly Eckert, who died in the Flight 3407 crash.

After the San Francisco crash, Western New York’s four House members and both of New York’s senators wrote a letter to FAA Administrator Michael P. Huerta, asking that the agency complete those regulations on time this year.

Also, Sen. Charles E. Schumer, D-N.Y., called Huerta, who reiterated the agency’s plans to implement the new safety regulations promptly. “He assured me unequivocally that that’s what’s happening,” Schumer said.

Then again, those regulations may not be enough to prevent another crash such as the one in San Francisco.

Robert A. Clifford, a prominent aviation attorney based in Chicago, noted that ever since the crash that killed Wellstone, the NTSB has been pushing – to no avail – for the installation of a low-airspeed alarm for pilots in all commercial aircraft.

Reflecting on what happened in San Francisco, Clifford – who represents several of the Flight 3407 families – said: “Once again, we’ve got another potential for graveyard engineering, where post-crash we fix things that we really knew about before the crash.”