In the wake of the turbulence that struck United Airlines Flight 767, injuring passengers and flight attendants, the question arises: is the airline industry and is the Federal Aviation Administration (FAA) doing everything possible to prevent mayhem from convective winds? The answer: probably not.
The reason: injuries and even deaths continue to occur on a regular basis. The Tuesday 20 July turbulence encounter of the United B777 wide body twinjet was reportedly the third such event for the airline this year. But who knows? At least six such airline encounters have occurred worldwide this month; the annual incidence is obviously higher.
And clearly something is amiss in turbulence avoidance and injury mitigation policies, because frightening and even deadly encounters with potentially bone breaking turbulence continue to occur.
Commercial airplanes run into turbulence 5,000 times a year, according to one account. Most of the encounters are above 10,000 feet. Injury claims alone track into the tens of millions of dollars annually.
The National Transportation Safety Board (NTSB) will be investigating the event. The NTSB will reconstruct the weather at the time, the actions of air traffic controllers and the pilots. Although the NTSB is known more for investigating crashes, this turbulence encounter put people in the hospital; thus, the NTSB is empowered to investigate and make recommendations to ameliorate the hazard.
At this point, general outlines of the accident can be reconstructed. United flight 967 was en route from Dulles International Airport near Washington DC, bound Tuesday night for Los Angeles International Airport. There were 255 passengers and 10 crewmembers aboard. Over Kansas, directly in the path of the westbound jet, a rapidly forming severe thunderstorm was boiling upward. The storm climbed from about 25,000 feet to 45,000 feet in 30 minutes. It produced large hail, indicating the presence of severe turbulence. Updrafts of 50-100 mph are not uncommon.
Radar image of Kansas about the time that United flight 967 enciuntered severe turbulence.
The plane was flying at 34,000 feet, directly into a wall of convective turbulence. Flying into this wall, the airplane jumped. The rapid change in altitude, as in previous turbulence encounters, caused everything not secured by straps, locks, latches and whatnot to be hurled about the cabin. This includes people.
One passenger described the encounter as “just a huge up and down.” She said her seatbelt was tight; the woman sitting next to her hit her head on the side of the cabin, and a girl across the aisle flew into the air and hit the ceiling.
It is not known how many passengers were wearing their seat belts; the seatbelt sign was illuminated at the time. It is not known if the word had been passed from the cockpit to be seated with seatbelts latched because of impending turbulence..
Four flight attendants were injured. It is not known if they were standing at the time or were strapped into their jump seats. Flight attendant jump seats, unlike 16G passenger seats, are only 9G capable and they have collapsed in previous incidents, injuring flight attendants.
Passengers screamed as the airplane bounced in the turbulence. The uninjured flight attendants calmed everyone down fairly rapidly.
Because of the injuries, the captain elected to divert the flight to Denver for immediate medical attention of those individuals who were hurt. The airplane landed at 7:45 pm and the injured passengers and flight attendants, about 25 in all, were treated by paramedics at the scene and then transported to hospital. About 19 were released from hospital the following morning.
The airplane was inspected and found to be structurally sound. Unknown, however, is the condition of the cabin. In previous incidents, sidewall and ceiling panels have been displaced, and overhead bin doors have popped open, spilling their contents and contributing to injuries and the general sense of mayhem.
At Denver, a few of the braver passengers boarded another United flight for Los Angeles.
Given that records exist of the upwelling thunderstorms along the airplane’s route, a number of pertinent issues are sure to be explored by investigators:
— Did air traffic controllers see the convective activity on their scopes? If so, what did they tell the pilots? Additionally, controllers would be in receipt of Pilot Reports (PIREP) which should generate a SIGMET (significant meteorological activity) that’s broadcast to all aircraft in the area.
— What did the dispatcher at United operations center know about the evolving weather, and did he do anything?
— Did the pilots see the convective activity ahead on their weather radar? If so, did they attempt evasive action or continue on their flight path? Did they make a public address (PA) announcement about the turbulence ahead? Were flight attendants ordered to be seated, or were they caught by turbulence while checking passenger seat belts?
— What is the United Airlines policy to flight crews regarding convective weather activity? Is at a 10 mile avoidance policy? A greater distance? Or is there no policy at all at United? It is clear that policies run the gamut from one airline to another; a more uniform avoidance policy – established by the FAA – may make for predictability and safer travel throughout the industry.
— The vulnerability of the cabin to damage and disruption caused by in flight turbulence is unconscionable, given that these events have been occurring for years. Every seat should be stressed for 16G. Every person should be strapped in, including so-called “lap children.”
— Perhaps overhead bin doors with their flimsy latches should be redesigned, to include an electric lock activated from the cockpit on pushback to secure the bin doors until landing.
— The in-flight safety video could include two crash dummies subjected to severe turbulence while seated. One dummy could be strapped in; the other not. Passengers would see the risk of not having the seat belt affixed immediately.
— Northwest Airlines employs a Turbulence Plot System that is regarded as the gold standard for turbulence avoidance. Based on FAA data from 1980-1996, Northwest had the lowest turbulence encounter rate among six major U.S. commercial carriers. Other airlines have purchased the system, but not – according to a 2010 report – United.
The issue is not who voluntarily adapts a proven system, but whether or not the FAA has evaluated the Turbulence Plot System, found it effective, and mandated its adoption across the industry.
This latest event may have been caused by rising turbulent clouds over Kansas, but the long miasma of complacency at the FAA about cabin structure and turbulence avoidance are the root causes of continuing injury.