It only took 20 minutes from the time the pilots of Swissair Flight 111 noticed a strange smell in the cockpit to when it crashed into the Atlantic Ocean just off Peggys Cove, killing all 229 on board.
To this day it remains one of the deadliest airline crashes in history. The ensuing investigation took five years and cost millions of dollars, and resulted in 23 recommendations.
Even 20 years later, the crash attracts interest from the aviation world — in part because of its tragic consequences, but also because of what was learned.
Paul McCarthy is the former air safety chair of the Air Line Pilots Association, and was qualified to fly the U.S.-manufactured McDonnell Douglas MD-11, the same type of plane that crashed off Nova Scotia. McCarthy was involved in some of the oversight surrounding the crash probe.
As with most crash investigations, McCarthy said with Swissair 111 there was no “shiny object,” no one cause investigators could point to.
“Air safety is really a process of incrementalism,” he said. “There are so many things that I can take away from this accident (and) every one of those opportunities is a learning point.”
Remembering Swissair Flight 111
According to the final crash investigation report, a short circuit occurred in the plane’s in-flight entertainment system. This sparked a fire above the cockpit ceiling, which ignited flammable material that was used in the plane’s acoustic insulation blankets. There was some discussion between the flight deck and air traffic control about whether to revert to Boston or land in Halifax, but the blaze spread quickly throughout the plane causing a rapid succession of aircraft systems-related failures, and then, at 10:31 P.M. local time — 53 minutes after takeoff — Swissair flight 111 crashed into the Atlantic Ocean, disintegrating on contact.
McCarthy points to an old adage in the air safety world called the Swiss cheese model, that says an accident doesn’t happen unless you have a whole bunch of holes that line up perfectly.
“If they never put an in-flight entertainment system in, the accident doesn’t happen. If they land in Boston when it starts to smoulder, the accident doesn’t happen. If they did an emergency descent, which is very uncomfortable, they might have gotten it on the ground in Halifax before the lost control of the airplane,” he said.
But the Swissair 111 investigation did contribute to safer air travel, McCarthy said. For example, communication between pilots and crew is much better now than it was 20 years ago, he said. And Kapton insulation on electrical wiring, which made it easier for the wire to short circuit, is no longer used.
“The Canadian government did a first-class job of investigating a very difficult accident in horrific conditions. They took their time, they analyzed it properly and they put recommendations out that can be implemented in the field, and as a result of their efforts and the efforts of the people who were associated with the investigation air safety became better,” he said.
Kathy Fox, chair of Canada’s Transportation Safety Board, which led the investigation in collaboration with U.S. officials, said she believes a lot was learned from the Swissair accident.
“You can never say it’s totally safe, there’s always going to be risk, but a lot of the issues that were identified as a result of the Swissair accident have been corrected and that’s definitely reduced the risk of these kinds of fires,” Fox said.
Twenty years after the Swissair crash, out of the 23 recommendations, nine are considered fully satisfactory and marked as closed. Eleven are dormant, meaning some action has been taken in Canada but not enough that the TSB is willing to close them. Three are still active.
While each country has its own rules and regulations, Fox explains that all major airplane manufacturers and regulatory bodies such as Transport Canada and the Federal Aviation Administration communicate and generally attempt to follow safety recommendations in their own countries and harmonize with each other’s standards so that aircraft can be not only operated more safely, but can be flown, bought and sold around the world.
Of the Swissair recommendations, Fox there were some that have been universally followed, at least in the West, such as a ban on the use of metallized polyethylene terephthalate as covering on thermal acoustic insulation blankets, which is believed to have contributed to the spread of the blaze that led to the crash.
Safety procedures have also improved. Fox said in Swissair 111, the crew didn't realize the severity of the fire and had begun doing things to prepare for landing such as putting away trolleys and dumping fuel.
“Now people realize if there’s smoke you need get on the ground as soon as possible,” she said.
But Fox said there is still work to be done. One of the active recommendations focuses on the need for more realistic testing scenarios for airplane wiring. The others involve cockpit recording and the need to have a two-hour recording capacity and 10 minutes of backup power.
“The situation with Swissair is that because of the fire it basically deprived the investigators of cockpit voice recordings in the last six minutes of the event. We don’t know exactly what was going on at that time,” Fox said. “Having a better recording capacity isn’t going to prevent the accident but it’s going to help investigators determine what happened which can reduce the risk of future accidents.”
Later this year Fox said the TSB will examine a number of recommendations from Swissair and other incidents that have been active for 10 years or longer and assess the progress that has been made and what needs to be done to satisfy them.
Jürg Schmid is a pilot and air safety expert from Switzerland. He was the head of the safety department of the now defunct Swissair during the time of the crash. He said the crash has made air travel safer in many countries, including Switzerland, which he said has attempted to follow all recommendations out of the investigation.
But he has his doubts that they’ve been followed around the world, especially when it comes to replacing flammable MPAT material in aircraft, which was quite expensive.
“There was quite a resistance of change of the insulation blankets of thousands of aircraft because the industry said ‘Well we just can’t do it.’ My feeling is that it’s not done everywhere where it should have been done,” he said
On the whole, at least in the West, McCarthy said flying is much safer today than it was 20 years ago.
“Twenty years ago the pilot associations would staff for and budget for five major fatal accidents a year just within our own membership, and most of the time I was involved with it we pretty much hit on budget. Today you have to scratch your head to think of the last real passenger fatal accident in North America,” he said
“We have gotten so incrementally safer in what we do, and it’s the culmination of designing better airplanes, training better pilots, and giving pilots and air traffic control and mechanics better and better tools to be able to do their job safety, and we have done that because of all the accidents that came before.”