By Ron Lundquist
There’s an old saying that goes something like this, “Learn from the mistakes of others; you won’t live long enough to make them all yourself.”
I’m not quite sure who said this first. Some say it was Oliver Wendell Holmes, others attribute it to First Lady Eleanor Roosevelt. I’ve even heard that the late great Bob Hoover used the phrase to remind us to learn from those who have had incidents or accidents, so we don’t repeat them. I think it’s solid advice. Aircraft accidents have been around since the Wright brothers, as they are an unfortunate consequence of aviation. It’s both what we learn from them and how we improve that makes these accidents not in vain.
I’d like to highlight several accidents (most in the airline world) that helped in part change the way we do things, or have in some part dictated the equipment we are now used to. My goal is to bring awareness to the crash itself and how it helped change aviation. It may not have been the sole reason things changed, but they certainly helped. My intent is not to trivialize anyone’s misfortune. These all happened, were horrible, and people died. They did, however, help prevent future disasters by what we learned from human behavior and helped develop technology, which did the same. That being said, just because an accident happens and we require a change of some sort, there’s nothing that says the same exact event can’t happen again.
So, let’s get started. On July 19, 1989, United Flight 232 had an uncontained failure of the #2 (tail) engine, which severed the lines of all three hydraulic systems, rendering the flight controls unresponsive. Controlling it with thrust from the #1 and #3 engines, the crippled aircraft made its way to Sioux City, IA, and crashed landed on closed runway 22. A few of the ways this accident contributed to aviation safety:
- It was a fine example of Crew Resource Management (CRM) and illustrates the need for crews to train for it. It’s still used today as a case study in CRM.
- It reinforced the need for emergency response plans. Sioux City Airport had been perfecting theirs for several years before the event, but it really pushed other airports to rewrite their own.
- Mechanically, it forced McDonald Douglas to rework the hydraulic systems in the DC-10 (and the MD-11.) Fuses were installed, to isolate sections of the hydraulic system if they were punctured, to prevent a total loss of fluid.
- A crack in the fan blades on the #2 engine was initially the culprit for the engine coming apart. After the crash, General Electric developed new inspection processes for these fan blades. They also started to use a higher temp and vacuum process for the titanium from which the blades were made.
For the next one, we go back to December 29, 1972, when Eastern Airlines Flight 401 crashed in the Florida everglades, while on approach to Miami, FL. The Lockheed 1011 had a burned-out light for one of the landing gear. While circling west of the airport, the autopilot became disengaged and the aircraft entered a slow descent. While all three crew members were focused on the light, no one was watching the airplane, which subsequently crashed. It helped coin the term Controlled Flight Into Terrain (CFIT).
- This accident continues to send the message that someone has to fly the airplane at all times. This is a major component of CRM and continues to be highlighted in CRM training.
- Not in 1972 but today, Part 121 aircraft have Ground Proximity Warning Systems (GPWS). If the L-1011 would’ve been equipped with this, it’s quite possible the crew would’ve been alerted to the impending impact with the terrain and could have arrested the descent.
- The approach controller at Miami did see the L-1011 deviating from its altitude, but the type of radar he was using was ancient by today’s standards. The controller testified that his radar would indicate incorrect information for up to three sweeps, but instead of directly asking them about their altitude, he asked them, “How are things coming along?” After this, air traffic procedures were developed to aid flight crews, when marked deviations in altitude are noticed by the controller. It also kept the push going for development of more accurate and timely radar.
- While waiting for rescue after the crash, many of the flight attendants were trying to help passengers evacuate the aircraft but couldn’t see, as it was night and they did not have flashlights. A recommendation from the National Transportation Safety Board (NTSB) was to have flashlights at all flight attendant stations. Also, the shoulder harnesses from the rear facing flight attendant seats had been removed, as it wasn’t a requirement at that point. It is now.
September 25, 1978, a Boeing 727 operating as Pacific Southwest Airlines (PSA) Flight 182 crashed northeast of San Diego’s Lindbergh Field while on approach to runway 27, after colliding with a Cessna 172. There are many facets to this crash, but essentially the PSA jet was talking to San Diego tower and the 172 was talking to nearby Miramar approach control. Both aircraft were on roughly the same heading, with the 172 climbing and the 727 descending for landing. The PSA crew thought they had spotted the Cessna but then either lost it or had mistaken another airplane for the Cessna. Blame for the accident is still being argued, but it did yield some high profile recommendation from the NTSB,
- Air traffic procedures were extensively overhauled at San Diego and a terminal radar service area (TRSA) was installed at Lindbergh Field.
- Traffic Collision Avoidance System (TCAS) was recommended to be installed in all Part 121 aircraft. Had the 727 been TCAS equipped, it certainly could have alerted the crew to the Cessnas altitude and track.
- Sterile Cockpit: a requirement for pilots to refrain from any nonessential activities during critical phases of flight. This includes taxi, takeoff, landing, and while in flight below 10,000 feet. An off-duty PSA pilot was catching a ride to San Diego on the accident flight and was in casual conversation with the flight’s crew for much of the approach into San Diego. While this may not have been a cause, it certainly took the crew’s attention away from effectively scanning for the Cessna. This was yet another accident that would show the need for sterile cockpit procedures.
Korean Air Lines Flight 007 was shot down when it strayed into Russian airspace on September 1, 1983. The 747 was enroute from Anchorage, AK, to Seoul, Korea. It is believed that the aircraft’s autopilot was operating in ‘Heading’ mode versus ‘INS’ or Inertial Navigation System mode, which sent it on a slow diverging path that would cross over the Russian Kamchatka Peninsula.
Until this time, the Global Positioning System (GPS) was controlled by the military. Long-range navigation in the civilian world was done with an INS, which is a device that uses accelerometers, gyroscopes and a computer to continuously calculate the position, orientation, and velocity of an object. It’s fairly accurate but does have limitations and doesn’t compare to GPS.
- The Flight 007 event changed long range navigation in several ways. It forced a protocol that required long-range military radars to assist in managing civilian air traffic. Three years after the shootdown, the United States and Russia established a joint air traffic system that would aid in preventing future tragedies.
- Two weeks after the tragedy, President Ronald Reagan announced the release of GPS technology to use in the civilian world. This fundamentally changed not only aviation but nearly every person’s life on the planet.
Pilots that have learned to fly in the last 30 years are no doubt very familiar with the term “microburst.” Before that, it was probably referred to as a downdraft, but the seriousness of them were really brought to light after Delta Airlines Flight 191, which crashed short of the runway at Dallas/Fort Worth International Airport (DFW) on August 2, 1985. The L-1011 had been skirting thunderstorms on their approach to the airport and were configured for landing, when they encountered a microburst they couldn’t out fly.
- After the investigation, the NTSB recommended that onboard windshear detection equipment become required on all airliners and were by the mid 1990’s.
- Low Level Windshear Alert Systems (LLWAS), a series of censors stationed around the airport to detect wind direction and velocity, were installed at DFW but were very basic in their ability. They could only detect changes close to the ground, not up in the air 1000 feet, where Delta Flight 191 was. After the crash, updated versions of LLWAS were developed and continue to be improved today.
- Terminal Doppler Weather Radar (TDWR): TDWR has the ability to “see” turbulence, cloud rotation, etc. Almost every weatherman on television today has access to TDWR. The technology was in its infancy in 1985, but by 1994 was in service and now protects at least 46 high capacity airports (and cities) in the U.S. It’s worth mentioning that the last accident attributed to windshear was July 2, 1994.
The last one wasn’t an accident and no one was hurt, but it could’ve been one of the biggest disasters at Chicago’s O’Hare International Airport. On July 23, 2006, an Atlas Air 747 had just landed, while a United 737 was departing on an intersecting runway. Too late to abort its take off, the United aircraft cleared the tail of the 747 by 35 feet. The incident was attributed to many things but ultimately blame was given to the tower controller, who did not monitor both aircraft with respect to them using intersecting runways.
- Runway Status Lights (RSL) had been in development for a few years, but after this incident, the number of towered airports that saw the implementation of RSL’s increased dramatically. They are used at busier airports, so depending on where you fly, you may or may not have seen one. It is important however to know what they mean if you do. RSL’s are fairly simple in their operation. The system communicates with Airport Surface Detection Equipment (ASDE) and warns runway users that a runway is occupied, either by another aircraft or ground vehicle. Red lights will illuminate, indicating to not cross a hold short line, a runway intersection or not to take off if you were on a line up and waiting for clearance. You will see more of these as airports become busier.
When we discuss accidents/incidents that contribute to safety and technology, these are just the tip of the iceberg. There are many more advances in aviation, whether in mechanical or human factors that have come from unfortunate events. Remember that rarely does any one thing cause a crash. It’s normally a chain of events, so the reasons for an event can vary from a few to many. I try to learn from every single one and become a better pilot from them. In no way am I second guessing crews, controllers, or investigators when highlighting what happened. I’m merely mentioning them in an effort to bring awareness.
Blue skies and tailwinds!