How To Prepare For Pitch Trim Failures, Part 3

The NTSB investigation noted that the first officer of the Cessna 550 air ambulance that crashed in Lake Michigan, who was 65, was not a full-time professional pilot but rather was a businessman who flew part time.

Key red flags on the FO’s performance were noted during the review of the cockpit voice recorder (CVR). The FO was unaware that he had selected an improper standard instrument departure page, was confused about the taxi instructions, responded to an ATC communication for another aircraft, and misstated the accident jet’s call sign during three radio transmissions.  

Further digging into the FO’s background revealed other red flags in his training records. For example, records indicated a check ride flight time of 2.5 hr., however, the aircraft’s records indicated only 0.6 hr. flight time for the flight training and check ride.

A search of FAA incident records indicated that in December 2002 the FO inadvertently took off with the electrical generator switches in the “off” position and did not follow the approved emergency landing gear extension procedures, which resulted in a gear-up landing. 

Other pilots in the organization revealed to NTSB investigators that the pilot “had no idea how the airplane operated” and would often act without thinking.  Other deficiencies included his tendency to over load and difficulty flying a stabilized approach without coaching.

After consideration of these factors, the NTSB determined that the operator’s operational safety deficiencies, including inadequate check rides administered by the company check airman, and the FAA’s failure to detect and correct the deficiencies that placed a pilot who inadequately emphasized safety into the position of chief pilot and check airman, as well as placing an ill-prepared pilot into the FO’s seat, contributed to the accident.

Lessons From The 737 Max
The initial reactions to a pitch trim failure must be exactly correct for the specific make and model of an aircraft, otherwise the consequences of less-than-correct control inputs can allow further degradation in the control of the aircraft. Depending on the cause of the unexpected aircraft motion, the correct control inputs must be made immediately, or else the condition of the aircraft will exceed the limits for recovery. 

This point was illustrated by the Boeing 737 Max accidents in October 2018 and March 2019.

In the immediate aftermath of the two accidents, there were pilots with years of experience in the “classic” 737 who confidently proclaimed that they could have prevented these accidents through application of the standard corrective procedure. They had been trained to react to unwanted autopilot trim or manual trim runaway by holding against the trim. This would activate the column cut-out switch, shutting off the flow of electricity to the horizontal stabilizer trim motor.  

Further steps included counter-trimming or activating the CUTOUT switches on the pedestal. Colleagues with decades of experience in the classic 737 said that this training element was simple to accomplish and took only a minute in a simulator. In their words, this was a “simple, no-brainer” corrective procedure.

The woefully inadequate transition training packages given to pilots prior to the accidents did not adequately inform pilots on the important differences in the Boeing 737 Max’s flight control system. The trim system in the Max’s Maneuvering Characteristics Augmentation System (MCAS) was not stopped by simply moving the control yoke. Boeing bypassed this function because countering the MCAS by pulling back on the yoke could negate the system’s purpose.  

The MCAS could only be deactivated if pilots counter-trimmed the aircraft manually or hit the CUTOUT switches on the center pedestal to override the system’s attempt to automatically pitch the jet’s nose down.

A vital lesson for the industry to understand from the Max accidents is that one can’t assume that the corrective procedure for a variant of the make/model will be exactly the same. Applying “this worked in my previous aircraft” overlooks the important differences in an aircraft’s specific handling characteristics and flight control systems.

When pilots are transitioned into an aircraft with unique flight control characteristics, there needs to be adequate visual and audio descriptions for a pilot to understand the handling differences, and then sufficient hands-on simulator training to develop the proper primal inputs. This should also be emphasized during type-specific upset prevention and recovery training.

The recommendations from the accident investigations should be incorporated into aircraft guidelines and simulator training. The management of pitch trim failures deserves more attention. Instead of the monotonous hours in recurrent training spent re-drawing the electrical system, one could argue that a more worthwhile expenditure of that important time would be to explore pitch trim failure.

Similarly, for those of you who have to perform steep turns and every variation in approach procedures during simulator training and checking, perhaps a portion of that time should be spent getting exposure to challenges of handling a pitch-trim failure.

How To Prepare For Pitch Trim Failures, Part 1: https://aviationweek.com/business-aviation/safety-ops-regulation/how-pr…

How To Prepare For Pitch Trim Failures, Part 2: https://aviationweek.com/business-aviation/safety-ops-regulation/how-pr…