The Error Chain as described by James Reason is deeply rooted in aviation doctrine today. The “Swiss Cheese” model is part of every course in aviation safety and repeated hundreds of times before a pilot receives his/her Commercial Certificate. So rather than repeat the concept, it might be good to examine the Error Chain through a quintessential and flawless example of System Failure.
Recently a small commercial aircraft and an airline turbojet took off at the same time on converging runways. The smaller airliner took off after the Captain mistook a clearance for the larger aircraft. The resulting condemnation and shock by the media, public and uninformed blogger/twits-ter types was overwhelming. It did not help that the Contract Tower controllers jumped the gun (operating under different rules than government controllers) and called the FAA Region declaring the incident was the fault of the pilot in the smaller commuter aircraft. This self-serving maneuver was a defensive measure to cover ATC shortcomings. After which, the Regional FAA Spokesman in Los Angeles regurgitated the charge for all media and the world, without any investigation or verification. That gave it the force of gospel, if the FAA Spokesman declared it happened...it must be so. He went on to say, oh, by the way we are still investigating. In spite of the media frenzy on television and social media, the contract tower personnel tower nor the FAA Regional Office ever informed the local FAA Flight Standards District Office (FSDO) nor the Principal Operations Inspector (POI) for two days.
Bottom line; the Captain of the smaller commuter plane took off without a clearance. If that is true, what does that have to do with the Swiss cheese model? As it turns out this is a school-book example of the Error Chain and how it can lead to two aircraft taking off at the same time. The Captain of the smaller commuter was properly trained, qualified and on his second revenue flight with the company. The normally single-pilot cockpit was staffed with a second, high time Captain offering coaching and mentoring to the new pilot. It is assumed the Scheduled Air Carrier crew was equally qualified for their job, sipping coffee and discussing the merits of their 80% pay raise. So how can the two pilots mistake the takeoff clearance meant for the turbojet? As it turns out....easy. Guglielmo Marconi, an Italian inventor, proved the feasibility of radio communication. He sent and received the first successful transatlantic radiotelegraph message in 1902.
The National Airspace System in the year 2017 relies completely on technology dating from 1902. In spite of technology advances where dropouts hiding in their room in their parents’ home can hack into a DOD computer and steal national secrets, the FAA’s primary aircraft collision avoidance method is the human eyeball. “See and avoid.” In this example, it was the lookout by both pilots, not ATC which prevented an accident. All the hysteria about privatization of ATC, closing runway 4L at HNL, runway incursions and the like are a direct result of a system which relies completely on technology from the early 1900s. The safety of the traveling public and commercial aviation relies onradios, radio transmissions and the human ear. Forget GPS, TCAS, TAWS, TIS and other alphabetdevices. They are Situational Awareness Tools. Notwithstanding the use of the light gun, to get a pilot in his/her aircraft safely from the ground to the air and safely back to the ground is solely based on radio transmissions. This so-called “system” is prone to failure.
So where are the failures which caused this incident and how can the rest of us keep from making the same mistake?
- Numbering / Call sign
– The turbojet had a call sign 155
–The commuter had a call sign 865
–One runway was designated runway 5
Similar sounding numbers whether call sign, runway, heading, altitude and others are constantly misspoken, misunderstood and mistakenly used.
- Line of sight
–The turbojet was closer to, and in direct line of sight with the tower
–The commuter airplane was not in sight of the tower and airport buildings blocked radio transmissions
Radio transmission quality is directly related to line of sight between transmitter and receiver.
- Human performance
–The turbojet crew while still taxiing had an expectation of a takeoff clearance
–The commuter crew while holding short of the other runway had an expectation of a takeoff clearance
–The controller had an expectation of takeoff sequence for both aircraft
–The controller (assumedly) saw the turbojet aircraft take the runway for takeoff
–The controller did not see the commuter aircraft line-up and takeoff on the runway although it was visible for over a minute and a half
Expectation is an essential element of the movement of aircraft within the airspace system. Controllers have an expectation of what pilots will do; pilots have an expectation of what clearances they will be given. Since expectations are continually met for controllers and pilots flight after flight, there is an expectation bias on the part of every human in the airspace system.
- Radio Discipline
–The controller issued a takeoff clearance
–Both crews replied to the transmission simultaneously, the commuter pilot’s transmission slightly longer revealing that two crews responded to the same transmission
–The controller did not catch the simultaneous transmissions
–The turbojet crew properly understood the clearance for their aircraft
– The commuter pilot mistakenly believed the takeoff clearance was for his aircraft
–No one in this situationunambiguously heard any transmissions
The safety system is comprised of several elements and when one or more of those elements fail, there is increased risk and a possibility of an accident.The flight operations system is comprised of Pilots and Controllers.Although there is clear evidence the ATC element of this system is partially responsible, it must be remembered that the Pilot in Command is responsible for the safe operation of the flight.
YOU are the PILOT IN COMMAND of your aircraft; no one else. Not the Chief Pilot, ATC or the FAA! YOU are directly responsible for the safety of your passengers. Passengers expect that you know what you are doing and expect a safe flight. Many pilots understand the PILOT part of PILOT IN COMMAND but many do not understand the COMMAND part. You must be the master and commander of the entire flight. YOU are the onlyCommander of the flight, no one else. Only YOU can safely operate the aircraft.
There are two words which should be common in your radio repertoire. When used regularly, these words will help you maintain control over a situation where you are confused by an ATC instruction or unexpectedly placed in a compromising situation.
STANDBY – Use this term when ATC issues a clearance/instruction as you are actively operating the aircraft and cannot immediately reply, respond or unsure if you can comply. Sort out the issue and only after you are sure you can comply with the ATC instruction, you can then reply. When you try to comply without clear understanding and/or confused, you are exposing your flight to increased risk and almost certainly a Pilot Deviation.
UNABLE – There is no obligation to comply with an ATC directive if you or your aircraft are not in a position to fully comply within operational specifications. Ask for an alternative or hold, stop and clear up the confusing or contradictory instruction before acting. DO NOT accept a clearance simply because it came across the radio. ATC controllers are not experienced pilots and do not know the operational characteristics of your aircraft. Use it when necessary. The safety of your passengers is the most important thing you need to remember as the PILOT IN COMMAND.
In an effort to reduce risk and potential Pilot Deviations review the following to prepare for your next flight.
- Review AIM Chapter 4, Section 2, Radio Communications Phraseology and Techniques.
- Review AIM Chapter 5, 5-2-1 through 5-2-4, Departure Procedures.
- Get training in radio discipline during training events during next recurrent training evolution.
Do not forget that HNL is #1 in the U.S. for Operational Errors and Runway Incursions. Listen up on the radio, comply with appropriate instructions and maintain a high Situational Awareness. Do not rely on ATC or others for the safe operation of your aircraft. If you do not clearly understand an ATC instruction, do not guess. Keep asking for clarification until you are sure you clearly understand and only then act accordingly.
Don't learn safety by accident