In this edition of Sydney Flyer resident Flight Instructor and Flight Examiner Bill Cooper reflects on the importance of acting with discretion while pilot in command.
Information based on an NTSB report:
In 1973, an Arab oil embargo threatened our carbon-based travel systems: In the US, a 55-mph car speed limit was introduced; people everywhere were focussed on getting along with less fuel.
A Boeing 727 Domestic flight crew, enroute with a full cabin, were indulging in the newly popular game of attempting better GNMPG (Ground Nautical Miles per Gallon) during cruise by trying small changes to flap setting. As cruise speeds were well above the wing slat (leading edge device) speed limit, they had been disabled by pulling the circuit breaker. A crew member, on re-entry to the cockpit, noticed the popped breaker and reset it. Major mistake!
As the slats deployed, one failed on the right wing. The airliner began a sharp, uncommanded roll to the right and entered a spiral dive from autopilot ‘Altitude Hold’ mode. From F390, despite the best efforts of the flight crew, the aircraft spiralled out of control, diving about 34,000 ft (10km) in just 63 seconds, rolling through 3600 twice and exceeding the aircraft’s structural Mach limit. Control was regained at about 5,000 ft (1.5km) after the gear was extended to slow the aircraft. Substantially damaged structurally, the aircraft made an emergency landing at a nearby airport. All lived, though there were 8 high-g injuries (‘When seated, wear your seat belt!’).
Early press reports of this very close shave lauded the crew for saving everyone’s life, but that faded when the real story came out. Though the cockpit voice recorder had been erased (which can only be done after landing and with the park brake on), the flight recorder held unambiguous evidence of what happened. Deep poo for the crew. The aircraft was repaired and returned to service.
All beings make decisions: ‘yes, maybe, no’.. ‘What’s for lunch?’ .. A zebra contemplating a crocodile-infested river .. Habit and instinct can usually guide such decisions, but this RPT crews’ decision making was of a different order. What was missing? Discretion. I.e., the limit of prudent judgement.
Flight crew should only make decisions during the flight related to minimising risk whilst moving payload expeditiously to the destination. Though no doubt unconscious of its consequences, this crew should not have attempted a risky, unplanned flight-test procedure during RPT flight. Discipline must have been lax anyway, as the returning crew member reset a breaker just because it was open. Even if the Flight Engineer (as carried on B727s) had done it, it should have been queried with the Captain before acting. The sad fact is that even mature, competent crew members with good safety records can make decisions that a well-trained student pilot would know not to.
Skilful decision-making is fundamental to safety. Multi-crew operations should be safer than single-pilot ops as opinions are shared, but in either case the choices made must be in the light of discretion, ie, judge what is prudent, wise and mitigates risk in the existing circumstances. No mad schemes (unless all else fails)!