An analysis of a deadly runway overrun

by Capt. G A Fernando, MBA

gafplane@sltnet.lk

RCyAF, Air Ceylon, AirLanka, Singapore Airlines and SriLankan Airlines
President Aircraft Owners and Operators Association, Sri Lanka

Former Chief Pilot Boeing 737
Former Deputy Chief Pilot Lockheed L 1011, Tri Star

Former Member Accident Investigation Team CAASL.
Former Crew Resource Management Facilitator SIA

On the night of 1st June 1999, an American Airlines Flight 1420, a MD 82 aircraft, was approaching Little Rock Airport, Arkansas, USA, carrying 139 passengers, with thunderstorms in the vicinity. They were over two hours late and the pilots were trying to beat the onset of weather ,which was already moving in creating intense precipitation (rain), reducing visibility and causing strong cross winds at speeds well beyond the limits imposed by the Company Operations Manual which the pilots had to follow. Little Rock is subjected to frontal weather. In the USA, cold air masses moves in from the north, literally ploughing under warm moist air from the south (Gulf of Mexico) and pushing upwards to create violent thunderstorms.

The resulting rain brings about down draughts of air which manifest themselves as wind after hitting the ground and spreading out. (Microbursts) causing a phenomenon known as low level ‘Wind Shear’ that can be extremely dangerous to aircraft approaching to land. It manifests itself as a sudden change of wind speed at low level which may make the aircraft fall out of the sky with insufficient height to recover!

Microburst

The pilots of American Airlines Flight 1420, had been awake for a long time and they were at the tail end of their fight duty period, after a long day. They were attempting to fly, looking for visual clues outside the aircraft, (they could see the lights of the airport occasionally), when it was really instrument flight conditions. Basically, there are two rules to fly by. Visual Flight Rules (VFR) or Instrument Flight Rules (IFR). After a mid-air collision over the Grand Canyon, USA, in 1956, where both aircraft involved were flying visually, it was required that all commercial airlines will file their Flight Plans in accordance to IFR until such time the pilots declare that they have the destination airport in sight. At this time, their flight is automatically considered a flight operating, in accordance with VFR. Trying to ‘eyeball’ known traffic even today is worse than looking for a needle in a haystack.

The two pilots of flight AA1420 had been aware of the forecast weather for Little Rock, before they departed on their short flight from Dallas-Fort Worth, Texas. Taking into consideration the speed of the moving weather fronts, it is relatively easier to forecast, accurately, expected weather at the time of arrival, in that part of the world, than in the weather in the Tropics. From the Cockpit Voice Recorder (CVR) the Crew were observed by the accident investigators, to be calm and collected till the actual weather at the airport was communicated to them by the Air Traffic Controller at Little Rock. They were fully expecting to get to their destination before the weather moved in. It looked as if the weather was closing in fast.

Then the ‘human condition’ kicked in and things happened fast. Through the years, while aviation technology improved and aircraft were more and more reliable, the human has remained basically in the Stone Age, fallible, unimproved and unreliable. (Essentially not supermen but of muscle, blood, skin and bone) and subject to fear and emotion. In reality, no flight is error free. Some observers, on safety audits, have detected over 300 errors made by a single crew on routine flights even in the best of airlines. Most individual crew errors are detected or are inconsequential. The few that filter through, gets picked up by the second crew member. If a serious error that gets through undetected, and results in an undesirable situation, that, too, could be corrected, even at the last moment. Thus saving the day. “To err was human” as said by Cicero. Through intense training and continuous evaluation, It is the role of the crew to avoid and trap errors, manage threats to air safety and mitigate their effects when necessary. Pilots don’t have control over threats, such as weather. That is how the system should work. As the aircraft gets closer and closer to the destination, the tolerance limits also narrows down. For instance, airlines fly along airways that are 10 miles wide at 30,000 feet and are expected to land on a Runway strip 150 feet wide, demanding greater flying accuracy from the crew resulting in greater stress. Greater the stress, greater the chances of making errors which are classified by the behavioural scientists as ‘Slips, Lapses, Mistakes and Violations’.

To illustrate the point, using the analogy of driving a car, if one is expected to drive at 100 kph in a freeway and the speed slowly creeps up to 110 kph, before one recognises the error it is considered to be a ‘slip’. If one forgets to wear one’s seat belt, the error is considered to be a ‘lapse’. If one attempts to overtake on a dual lane road, based on one’s judgement and then realises that there is a car coming in the opposite direction and one is forced not to overtake, that type of error is called a ‘mistake’. If one is aware that one is breaking the law and one continues to do so regardless, that becomes a ‘violation’. (Like crossing double white lines, when overtaking.)

With AA1420 the presence of thunderstorms in the immediate vicinity and associated lightning, turbulence, air speed fluctuations of the aircraft, provided distractions, there is a possibility of self-induced stress. This is exactly what happened. While attempting to align the aircraft on the runway, in strong cross wind condition, they landed a bit deep. Being too busy (task overloaded) on the final approach, both crew members forgot to arm the automatic Ground Spoilers, resulting in an overrun of the wet runway. The Ground Spoilers are the devices on the top surface of the wing that pop out and literally spoils the lift of the wings a few seconds after touch down. The spoilers operate automatically when armed, pressing the wheels to the ground to improve braking action. If that didn’t happen either crew member could, reach across and physically pull a handle that can deploy the spoilers manually.

There was another human consideration known in the industry as ‘Intra Cockpit Authority Level’, between the Captain and the First Officer. The Captain, in this case, was a 10,000-hour, former US Air Force Veteran and Management Pilot, while the First Officer was a new hire with low experience, who may not have wanted to suggest that the Captain aborts the landing approach and goes around or interfere with the controls, as it would be misconstrued as ‘mutiny’. The million dollar question is, why he keep quiet when it also involved preservation of his own life?

Usually, it is left for the Captain (the team leader), at the initial briefing, to set the tone, by saying something like “if you see me do something unacceptable or dangerous, please sing it out loud even at the risk of being embarrassed”, because the Captain may sometimes give a logical explanation for his actions afterwards. Unfortunately, from what we could gather from the Cockpit Voice Recorder (CVR) that didn’t happen. There wasn’t time for even a proper briefing which should have been done before the top of descent, covering all options including a possible diversion to an alternate airport with better weather, or to their departure airport, which was Dallas-Fort Worth where the weather was good. That could have been a far safer option than landing on a wet runway with high cross winds. While continuing the landing in high winds was a ‘violation’, in certain countries, the Captain and Crew are allowed to proceed down to a minimum altitude and ‘take a look’ and abort (go around) the landing, if the situation is deemed to be unsafe. To some airports, like London, England, it is illegal for the crew to even commence an approach if the landing conditions are unacceptable. This regulation was imposed after an Ariana Afghan Airlines approached in bad weather, with 62 people on board, to London Gatwick, England, 51 years ago, and crashed.

Anyway the final result with flight AA 1420 was that the aircraft couldn’t stop, skidded sideways, overran the runway and hit a man-made obstacle that was not frangible (Breaking on impact), destroying the aircraft, killing the Captain instantly and 10 other passengers. The wreck caught fire. The crash was avoidable if the pilots delayed their approach to land or diverted to another airport and if that killer obstacle had been removed by the airport authorities. After the accident, the Captain’s wife took the Airport Authorities to court and was awarded damages of 2 million US Dollars, against the authorities, for not having frangible obstacles in the Runway End Safety Area (RESA). A long day, Pilot fatigue and a behavioural phenomenon called ‘get -there-a–ritis’ (also known as get-home-a-titis) where the pilots were intent at landing at any cost, under self-imposed pressure may have been contributing factors. In the opinion of the Accident Investigating team, the thunderstorms were far too close to the airport and recommended that aircraft should not commence an approach for landing, if the thunderstorms were closer than five miles from the airport. It was also recommended that arming of the Ground Spoilers be included in the ‘Before Landing Checklist’ The Accident Investigation team took over two years (in the comfort of quiet, air conditioned command centre) to analyse the case of American Airlines 1420 and quite rightly stated that it would be unfair to solely blame the crew who had less than two minutes, in demanding conditions, to make crucial decisions between life and death. Their objective was to find the cause behind the cause

As a standard practice, the aviation industry learns from crashes that occur in any part of the world. Pilots in our part of the world are as human as anywhere else. It is very easy to imagine that a similar scenario could happen in Sri Lanka, where similar weather patterns are encountered during the Inter-monsoon seasons (evening thunder showers). I am sure we have all seen the mighty power and devastating effects of the wind just before the onset of a storm. They blow down trees and damage roofs. Doppler Radar, capable of spotting wind shear is still a dream. Obstacles at the end of the runway should be identified and removed because aircraft can be at the wrong place at the wrong time. It is a case of evaluating the risks, by the operating crew.

That is what Safety Management is about. According to the International Civil Aviation Organisation (ICAO), being proactive, predictive and preventive is the name of the game. Unfortunately, many want to be in the spotlight as ‘movers and shakers’ of the a Aviation Industry but wouldn’t give two hoots to make the system safer. We have seen in the past that It is difficult to hold anyone accountable after an accident. The easy way out is to blame the pilots.

Perhaps. as Anton Jones in his popular ‘Baila’ about the Martinair crash at Maskeliya, says “Kageda warada notherai” (We don’t know whose fault it is).

That is the stark reality.