Pilot Decision-making: Background

Had you taken Groundschool for a pilot licence fifteen years ago, this section in this course would not have appeared.  At that time, decisions made by pilots was not considered to be a “technical” component of aviation safety.  Fifteen years ago, however, commercial aviation—and in particular large commercial “transport” aviation—was just coming to terms with an extremely unfortunate incident that occurred in the Canary Islands, a small group of resort islands located off Morocco; this incident would forever change the way pilots, and especially air transport pilots, would be trained.  Transport Canada, like all civil aviation regulators world-wide, quickly instigated a program to train pilots that sound decision-making skills were fundamental to aviation safety—so much so that pilot decision-making became a mandatory component for recreational, private, and commercial groundschool training.

What happened in the Canary Islands off Spain is now legendary in the aviation community.  At about 5 p.m. on the afternoon of March 27, 1977, two Boeing 747s collided on a runway at Los Rodeos Airport on the island of Tenerife.  Within seconds, the lives of 583 people were extinguished.  The cause—a Senior Captain with KLM Royal Dutch Airlines—with an astounding 30-years experience with that Airline—was in a hurry.

Airlines served the heavy tourist traffic in and out of the Canary Islands by way of Las Palmas Airport on Grand Canary, but in the early afternoon of March 27th a terrorist bomb exploded in the terminal.  Shortly after the explosion a bomb threat was received by the airport authorities regarding a second bomb, and Las Palmas Airport was quickly closed, forcing in-bound traffic to divert to the much smaller and ill-equipped Los Rodeos Airport on Tenerife.  By the time the KLM 747 arrived at Los Rodeos, the ramp and apron facilities were crowded aircraft bound for Las Palmas Airport, and conditions became even more difficult when a Pan American 747 arrived a half-hour later after being diverted on its trip from New York.

As flights became diverted, the facilities at Los Rodeos became overtaxed, and the pressure began to mount on the shoulders of Captain Jacob Veldhuyzen van Zanten, KLM’s chief training captain on the Boeing 747s.  Captain van Zanten’s responsibilities included ensuring that he and his crew’s “duty time”—the time that a flight crew remains at work without rest—did not expire.  If the duty time reached the allowed limit established by KLM, the crew would not be able to leave Los Rodeos until after an overnight rest.  He would have to find short-notice accommodation for his 234 passengers at considerable expense and inconvenience for the airline; Las Palmas Airport might not be re-opened before his crew’s duty time expired at 6 p.m. that afternoon.

The two 747s were parked tightly together on ramp bay near the threshold of the one runway that served Los Rodeos; when Las Palmas airport did re-open and aircraft began to depart, the positioning of the two 747s was such that the PanAm 747 could not taxi for takeoff until after KLM 747 taxied.  Earlier that afternoon, Captain van Zanten made the decision to refuel his aircraft, anticipating that there would be delays later when back-logged aircraft converged on Las Palmas.  As a result, when Las Palmas did re-open and aircraft began departing from Los Rodeos, the PanAm crew had to wait an additional 35 minutes while KLM aircraft was refuelled.  To add to the strain situation, the weather at Los Rodeos began to deteriorate as fog began to move in from off-shore.

At 4:30 p.m. the KLM requested a taxi clearance, but by this time the runway was almost entirely obscured by the fog with visibility fluctuating around 900’.  Because of the taxiway configuration, the PanAm 747 would have to follow the KLM 747, requiring that both would have to back-track (taxi) on the active runway.  When the PanAm crew contacted the tower controller as instructed, the visibility was such that the tower controller could not see the runway, and the PanAm crew cold not see the KLM aircraft which they were instructed to follow.  Now language became a factor as no longer could the crews and the controllers co-ordinate with one another using visual information.  While the controllers spoke English with heavy Spanish accents, the KLM crew spoke English with a Dutch accent.

While the controller instructed KLM to taxi back to position on the far end of the runway, the PanAm crew was instructed to leave the runway on the third taxi-way exit on the left.  The PanAm crew, however, was having difficulty identifying the taxiway intersections in the fog, not being sure of the number of taxiways they had passed.

At five minutes after 5 p.m. the KLM crew had reached the far end of the runway and had turned to position the aircraft for the takeoff roll.  As evidenced in the Cockpit Voice Recorder and the Flight Data Recorder, Captain van Zanten inexplicably advanced the thrust levers as soon as the First Officer completed the pre-takeoff checklist and the KLM aircraft began to move in the direction of the departure.  The PanAm 747 was still taxiing up the runway, but was now obscured from the view of the KLM crew owing to the fog.  “Wait a minute . . we don’t have an ATC clearance,” responded the KLM First Officer.  “No . . I know that,” responded Van Zanten, holding the 747 back with the brakes, “Go ahead and ask.”

The First Officer contacted the tower, reporting the KLM 747 was ready for takeoff.  Recordings of the transmissions indicate the Tower Controller responded by providing the KLM with its IFR routing clearance, but did not clear the KLM for takeoff.  But as the First Officer was reading back the routing clearance, van Zanten released the brakes and again advanced the throttles—this time to the takeoff-power setting.  The KLM was six seconds into its takeoff roll when the First Officer added: “. . we are now at takeoff.”  The Tower Controller responded: “Okay . . standby for takeoff . . I will call you.”

The PanAm crew heard the KLM transmission and sent out a desperate transmission—“We are still taxiing down the runway”—but their fate had been sealed.  The transmission of the PanAm crew was blocked.  While accelerating down the runway, van Zanten saw the PanAm blocking the runway, and he apparently made a desperate attempt to rotate prematurely and climb over the PanAm 747.  His last-minute effort to avoid the collision is thought to have saved the 70 people on board the PanAm 747 who survived, but only the nose of the KLM cleared PanAm, and the KLM fuselage and wing cut though the PanAm passenger compartment.  All persons on board the KLM were killed.  What was the cause?  Faulty pilot decision-making.1

After Tenerife, the astounding trend became evident.

  • Back in 1970 an Overseas National Airways DC-9 ran out of fuel over the Caribbean and was forced to ditch at night—22 died; the cause was the crew’s miscalculation of fuel consumption.
  • In 1972 an Eastern Airlines DC-10 descended inadvertently into the Florida Everglades while distracted by a cockpit light bulb that failed to indicate the landing gear was down, killing 99 people, but leaving 77 survivors (see P. 131).
  • In 1978 a United Airlines DC-8 ran out of fuel while making an approach into Portland International Airport.  The crew elected to circle south of the airport for almost one hour attempting to deal with a faulty landing gear problem.  Only 10 of the 189 occupants were killed, primarily because the cabin crew was already prepared for the planned emergency landing on the runway.

These are all but a few of the more dramatic cases of faulty pilot decision-making.

What about you?

If you have not previously noticed local aircraft accidents reported on TV news or in newspapers, your decision to pursue a pilot licence will certainly change all that.  Stories or reports of missing aircraft or aircraft “crashes” have little meaning for the public (although they certainly grab the public attention—at least initially).  For you, however, this will change.

As you hang out at airports, and develop your friendships with other pilots, you will eventually observe that pilots spend a lot of time doing “armchair” analysis of aircraft accidents and incidents; at the root of this is their desire to know about an unfortunate event so as to educate themselves.  They seek to ensure by casual, informal analysis that they do not suffer the same fate.  They use these occasions “gossip” and “hearsay” to reaffirm among themselves their safety practices, and to learn about what Donn Richardson2 calls the “gotchas” (hazards) of flying.

It is said by old pilots that, if you hang around aeroplanes long enough, you will see one bent.  Anyone who has seen a bent aeroplane knows how oddly “unrecognizable” they look, how they appear as tattered sheet metal, with little semblance of order and structure.  So if the old pilots are true, what can we do to stay out of trouble?  The solution is simple—learn from the mistakes of others, and never let it happen to you.  Is it really possible to ensure it doesn’t happen to you?  You bet it is.  A safe pilot is a pilot who is in control of every aspect of a flight.  He or she is the Pilot-in-command, and the command authority is rooted in the basic rule that the pilot can take whatever action is necessary for reasons of safety.  In developing your command authority as student pilot, assert command and control authority.  Practise your ability to effectively analyze situations related to flight operations, and develop your sound decision-making skills.  Take control aggressively to avoid potentially hazardous situations.

With command authority, there is privilege; but with this privilege there is responsibility.  You will learn the safety rules and rituals of flying—always get a weather briefing, always dip your fuel tanks prior to flight, always use a pre-takeoff and pre-landing checklist, set and never violate personal weather minimum, etc.—and these rules are crucial.  But the question remains—what happened to van Zanten?  And what could have caused all those other professionals to make simple errors in predicting fuel consumption.  Were they aware of the dire consequence of their decisions?


1 My comments on the Tenerife are based on the descriptions and analysis made by Macarthur Job in his excellent and highly recommended Air Disaster, Volumes 1 & 2 (1996, Fyshwick: Aerospace Publications Pty Ltd); there were many factors attributed to this infamous event at Tenerife and they are well documented and discussed by Job (see pp. 164-180 of Vol. 1).

2 Donn Richardson is a Flight Instructor, a professional aerobatic pilot, and a former DC-3 pilot; he was also Langley Flying School primary Pilot Examiner from 1994 to 2007.