An Asian airline's wide-body slams into a sea wall. A 737 with 150 people aboard hits the runway so hard its nose gear buckles. A cargo plane barely misses houses before plowing into a hillside short of the runway.
These recent accidents, marking the deadliest period for airlines in the US since 2009, have something in common: had the pilots aborted their landings at the first sign of trouble - a move known as a go-around - they might have avoided tragedy.
"They'd all be walking, talking and alive if they went around," Patrick Veillette, a pilot who teaches and writes about aviation safety, said in an interview.
The three US air crashes since July 6, which killed five people, spotlight the difficulty in getting pilots to abort touchdowns if they haven't made safe approaches to the runway.
It's "the largest, lowest hanging piece of safety fruit" to make flying less hazardous, according to research sponsored by the US Flight Safety Foundation.
Crashes that occur during approach or touchdown are the world's leading category of aviation mishaps and deaths, according to data compiled by Chicago-based manufacturer Boeing.
The biggest risk factor for such accidents is failing to approach a runway at the proper speed, altitude and heading, known as an unstabilised approach.
If safety regulators can persuade pilots to conduct more go-arounds, lives may be saved and costs to airlines in damaged equipment and liability may be lowered.
Computerised flight-track records and a survey of 2340 pilots sponsored by the safety foundation found that crews have a long way to go to comply with airline requirements to abort landings if their approaches were unstable. Almost all pilots, or 97 per cent, continued to land in spite of the rules that they climb away from the runway and circle around to try again, according to the research.
"That's a risk factor that we really need to work on," Rudy Quevedo, director of global programs at the foundation, said in an interview.
The issue isn't simple or new, Quevedo and Veillette said.
"There isn't a commercial pilot who can say, 'Shame on you. You should have gone around,"' Veillette said. "We've all been in situations where in retrospect, we should have gone around and didn't."
In some cases, rules may be overly rigid, akin to imposing a highway speed limit that is so low drivers routinely exceed it, Quevedo said. Violating the rules has become so ingrained that airlines don't enforce them and pilots don't recognize when they are taking unnecessary risks, he said.
Setting up a proper approach to a landing is critical to safety, according to the US Federal Aviation Administration, which regulates the aviation industry, and the United Nations' International Civil Aviation Organisation.
"It's really all physics," Quevedo said. "You want to be centered on the runway on the correct trajectory, the correct descent rate and the right speed."
If that happens, a plane will almost always cross the start of the runway at a height of about 15 metres, which is optimal for a safe landing, he said.
Airlines typically require that a plane be stabilized at 1000 feet (305 metres) above the runway in poor visibility and at 500 feet in clear weather. Pilots must also have performed required checklists, extended landing gear and configured the plane for landing, according to the foundation.
"If not - GO AROUND!" an FAA advisory to pilots and airlines says.
While the National Transportation Safety Board hasn't said what caused the three recent crashes, information it has released shows evidence of the aircraft being unstable at points within a mile or two from the runway or of pilots perceiving they were off course.
Pilots on an Asiana Airlines Boeing 777 that hit a seawall short of a San Francisco runway on July 6 said they had indications once they reached 500 feet altitude that they weren't properly set up to land, according to NTSB Chairman Deborah Hersman. The crash killed three passengers and injured dozens as the plane broke apart and slid to a stop.
One pilot told investigators the Asiana plane was below its optimal glide path at 500 feet, Hersman said July 9. Shortly after, the plane veered off the runway centerline, Hersman said.
The pilots told investigators they failed to notice other warning signs, including that their speed had slowed so much that the wings were in danger of losing lift. When they recognized what was happening, they attempted a go-around, adding power too late to avoid the accident, Hersman said.
A Southwest Airlines plane landed nose-first at New York's LaGuardia Airport on July 22, breaking the landing gear and skidding across the runway.
The NTSB hasn't said whether the Boeing 737-700 was on a stable approach. The captain took control of the plane from the first officer below 400 feet altitude, according to the NTSB. In previous NTSB cases, such shifts in control occurred after an emergency or because the captain thought the approach needed correcting.
Nine people suffered minor injuries, according to the NTSB.
The pilots of a United Parcel Service Inc. freighter that crashed in Birmingham, Ala., on Aug. 14 received a cockpit warning that they were descending too rapidly 7 seconds before they hit trees, NTSB member Robert Sumwalt said last month.
Whether the pilots also knew they were too low for their approach, which should have triggered a go-around, hasn't been released. The Airbus SAS A300-600F hit a dark hillside before dawn and broke apart, killing both pilots.
The NTSB has investigated at least 21 cases since 1999 in which pilots could have prevented accidents or incidents if they had aborted landings that ran afoul of airline rules, according to the agency's case files.
In an attempt to discover why such accidents continue to occur, the Flight Safety Foundation hired Martin Smith, a former pilot and psychologist who operates Presage Group Inc. in Mississauga, Canada. Smith oversaw the survey of pilots that found many weren't following airline rules.
The pilots who didn't go-around after an unstable approach tended to have a dulled sense of the risks and didn't communicate as much with fellow crew members, Smith said the survey showed. They also believed they wouldn't be reprimanded for attempting to land in those cases. A similar survey of airline managers is under way to determine why the rule is so widely overlooked, he said.
At the same time, some pilots said the criteria for a stabilised approach weren't realistic, Smith said in an interview.
Researchers are attempting to design new standards that require aborting landings only in dangerous situations, improving safety without unnecessarily boosting go-arounds, which can create their own dangers, Quevedo said.
"We should expect that if we have a policy, the people should follow the policy," he said. "But that being said, we need to make sure that the policy is good before we make people follow it. I don't think we're there yet."
- Bloomberg News