Can External Pressure Impact Pilot Safety?

A case study highlighting Business Aviation’s existential risk…

The loss of a Lockheed JetStar modified with 731-turbofan engines illustrates the pressure to perform that still exists today in Business Aviation, notes Jack Olcott in his summary of an accident that occurred decades ago.

Business Aviation provides transportation that is unique. Unconstrained by the volume of passengers desiring to reach popular destinations, a company with its own Flight Department can select when and where its aircraft should fly. Executives of companies using business aircraft expect their flight crews to perform, and flight crews want to satisfy their passengers’ needs.

While no one wants to incur inappropriate risk in achieving the company’s mission, often the lead passenger on a flight is incapable of appreciating why certain decisions must be left to the flight crew when communicating their travel request. Subtle, and at times not-so-subtle pressure to reach a destination is conveyed to the crew, often out of a lack of aviation knowledge by the travelling executive.

Hence most Flight Departments establish a safety protocol that clearly state decisions regarding flight are the sole discretion of the pilot in command and that passenger pressure to complete a mission will not be tolerated. Nevertheless, crews want to satisfy the boss. And risk increases exponentially with that desire to please.

Precursors

As flight departments transitioned to more fuel-efficient business jets in the late 1970s and early 1980s, aircraft such as the four-engine L-1329 JetStar were stripped of their thirsty turbojet engines and fitted with Garrett TFE-731 turbofan powerplants.

A flight department located at Westchester Country Airport (KHPN), situated about 20 miles north of New York City, operated two JetStar L-1329-731 models, and one had recently undergone a major modification to its electrical system and the replacement of its four carbon-pile Generator Control Units (GCUs) with solid-state units at a major service center on Long Island, south of KHPN.

During ground and flight tests of the modified JetStar following its GPU maintenance, several electrical anomalies were observed and not resolved.

Various GPUs were tripping off line for no apparent reason. While they could be reset without difficulty, the interruption of electrical power resulted in loss of certain avionics and flight instrumentation until electrical feed was restored. Obviously the electrical problems were a distraction and required the crew to focus on correcting the situation. Nevertheless, the JetStar was returned to KHPN.

Subsequent maintenance and testing by the Flight Department’s staff was unable to isolate the intermittent nature of the GPU problem between the aircraft’s return to its home base and a scheduled trip to Toronto, Canada (CYYZ) 12 days later. In the meantime, one flight between KHPN and Chicago’s Midway Airport (KMDW) had been flown during which several electrical interruptions were experienced.

The Flight

En route to Toronto, the aircraft’s GCUs suffered several electrical interruptions and were reset by the crew prior to landing at CYYZ and discharging passengers. Waiting for their return, the aircraft’s captain and co-pilot (who was also type rated in the JetStar and a certified Airplane & Powerplant Mechanic) spent much of their time communicating with their maintenance department at KHPN and with experts involved with the GPU installation, but nothing definitive was forthcoming.

According to personnel who met with the co-pilot while the crew waited in Toronto, the JetStar had lost electrical power for about nine minutes, during which time the cockpit had been without normal lighting and instruments. Pilots privy to the co-pilot’s conversation were inconsistent in their recall, but they all agreed that the JetStar had experienced electrical issues.

When passengers returned for the flight back to Westchester Country Airport as the business day concluded, the JetStar departed CYYZ a few minutes prior to sunset.

Before leaving Toronto Tower’s frequency, however, the crew reported a problem with the aircraft’s landing gear and requested clearance to return to CYYZ.

Shortly thereafter the crew stated that their problem had been resolved and that the flight would proceed to its destination, KHPN. (It was assumed that the gear and electrical problems were related.)

About 45 minutes after departing Toronto, the crew contacted Approach Control for the Westchester Country Airport area and was cleared to the Brews Intersection in anticipation of holding prior to receiving a clearance for the ILS approach to Runway 16.

Weather at KHPN at that time was very poor: 15 minutes prior to the crew’s initial contact with Approach Control, ceiling was reported as indefinite, 0 feet obscured, visibility 1/4, light rain and fog, wind from 200-degrees at 12 knots gusting to 21 knots, reflecting the effects of a rapidly moving cold front approaching the East Coast. Several pilots reported experiencing significant wind shear and turbulence while tracking the ILS to KPHN’s Runway 16.

Apparently the JetStar crew was experiencing electrical problems as they approached the Brews Intersection. Observing the aircraft significantly east of its required location, Approach Control issued specific headings to prevent encroachment into unapproved airspace and to reposition the JetStar in the hold at Brews. The co-pilot apologized for the lack of position, following shortly with a notification that “We’ve just lost the right side radios. That’s what presented us a problem there”.

Radar returns from the JetStar were intermittent, also indicating electrical problems consistent with the GPU issues experienced since the solid state units were installed several weeks earlier. The aircraft’s transponder was inoperative for 77 seconds approaching the Runway 16 outer marker.

Acknowledging the JetStar’s last transmission, Approach Control advised that Runway 16 RVR (Runway Visual Range) was varying between 3,500 and 4,000 feet, and visibility was 1/4th mile in light rain, adding “If you’d like, you can try it and see what happens”. The co-pilot responded “Sounds great, thank you” as the crew accepted vectors to the final approach course for the ILS to Runway 16.

When situated on the localizer, the JetStar crew was instructed to contact KHPN Tower and was cleared to land.

Weather at that time was reported by the Tower to be 5,500 RVR, and pilots were experiencing severe turbulence and wind shear on final.

One aircraft reported a 20-knot increase in wind-speed while approaching minimums. A Gulfstream that landed about 25 minutes prior to the JetStar’s approach encountered moderate to severe turbulence with large wind changes near the ground. The pilot of a Boeing 737 that followed the Gulfstream reported a 15-knot loss of airspeed, and similar reports continued until the weather front passed later that evening.

As the ill-fated JetStar descended on its final approach—its crew facing the demands of an intermittent electrical system and extreme weather conditions—local controllers at KHPN noticed the aircraft was deviating to the right of course and informed the crew that winds were from 200 degree at 23 knots.

But there was no acknowledgement. The aircraft impacted trees in a heavily wooded area about 6,000 feet from the approach end of Runway 16, about 2,000 feet right of the localizer centerline. There were no survivors.

The National Transportation Safety Board determined that the probable cause of the accident was a distraction to the pilot at a critical time as a result of a major electrical system malfunction which, in combination with the adverse weather environment, caused an undetected deviation of the aircraft’s flightpath into the terrain.

Why?

What would cause an experienced crew to dispatch in an aircraft with known electrical problems at night and elect to attempt a challenging ILS approach to an airport with reported severe turbulence and wind shear?

The rapidly moving cold front most likely had cleared or soon would clear the weather behind it, so that the crew could have landed west of Westchester County Airport or possibly delayed their flight.

Clearly they felt pressure to complete the trip as scheduled.

While not discussed in the NTSB accident report, local sources who were familiar with the ill-fated JetStar claimed that the lead executive being transported between Toronto and Westchester County that evening had an important appointment the next morning at the Memorial Sloan Kettering Cancer Center. That scenario may or may not have been at play.

Furthermore, the individual involved may have not exerted any pressure on the crew to perform. The motivation to complete the flight might have been entirely the crew’s desire to complete the mission. Professionals are motivated to succeed.

Success, however, is fundamentally about managing risk and getting all passengers home safely.

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