write your opinion and thought of this article. please DO NOT just repeat the information the author have already mentioned. be creative in your answer. thank you.
—————————————————————–
There are three different pitch modes built into an auto-flight system. They are vertical speed, flight level change (speed mode), and vertical navigation mode. In vertical speed mode, the aircraft will climb or descend at a rate specified by the operator. For example, the pilot can command the aircraft to climb at 1500’ per minute or descend at 2000’ per minute to the desired altitude. This mode is advantageous when air traffic controllers request to be at or go through an altitude by a specified time.
In flight level change mode, also known as speed mode, the aircraft will climb or descend at an indicated airspeed selected by the pilot to the desired altitude. For example, if in a climb and at a chosen airspeed of 250 knots, the aircraft will pitch for and maintain 250 knots. If the pilot increases the power, the aircraft will climb at a greater rate. Conversely, if the pilot decreases power, the aircraft will climb at a slower rate.
In vertical navigation mode, the aircraft will climb and descend as commanded by the flight management system. For example, let’s say the aircraft is descending on an arrival procedure. Furthermore, the arrival procedure states to cross WLMAN at 24,000’, TPGUN at 14,000’, and HLIWD at 10,000’, with the altitude preselector set at 10,000’ and the aircraft in vertical navigation mode, the autopilot will command the aircraft to descend and will cross all those waypoints at the specified altitudes.
Pilots of aircraft must be cognizant of which mode the auto-flight system is active due to inherent dangers. For example, on December 31, 2013, a Citation CJ2+ was in a climb to 43,000’. The pilot was climbing in vertical speed mode; the pilot stated he used this mode to climb because the aircraft tended to “hunt” in flight level change mode. The pilot lowered the rate of climb in increments of 500’ per minute as the climb continued. While passing 41,000’, the rate of climb was 1000’ per minute, but the aircraft’s airspeed was decreasing. The pilot noticed this and reduced the climb rate to 500’ per minute. The pilot diverted his attention to another task and didn’t notice the aircraft’s airspeed continued to decline; the aircraft stalled soon thereafter. The pilot did not perform the appropriate stall recovery technique, which resulted in the aircraft rolling five times and exceeding the wings’ load forces which caused substantial damage. Luckily, all aboard survived (Lacagnina, 2018).
A single pilot was operating the aforementioned Citation. The pilot stated in a subsequent interview, “the selection of a vertical speed of 500 fpm should have managed the aircraft’s energy sufficiently to achieve FL 430 without incident”(Lacagnina, 2018). Thus, he did not monitor his low energy state and decided to change his attention to looking up the forecasted winds aloft he had saved on his electronic flight bag (Lacagnina, 2018). It appears that complacency and single-pilot operations played a role in this incident.
Terry Tolleson, a writer for the Aviation Pros, identified three primary causes of complacency – “fatigue, too many things happening simultaneously, and too few things happening” (Tolleson, 2007). In the Citation case, it appears that too many things were happening simultaneously, and the pilot lacked prioritization of tasks.
Pilots need to prioritize the tasks at hand. A common practice at my company is always to have someone “flying the plane” during climbs and descents to ensure the aircraft’s performance is maintained and the aircraft performs as commanded (i.e., captures the altitude selected). This means we are not both eating or doing paperwork. Someone is always left to “mind the store.” Had the pilot reviewed the winds aloft forecast after the plane had leveled off at FL430, he would have most likely noticed the deteriorating low energy state of his aircraft and prevented the stall from occurring.
References
Lacagnina, M. (2018, November 19). A Moment’s Inattention. Flight Safety Foundation. https://flightsafety.org/asw-article/a-moments-inattention/
Tolleson, T. (2007, September 7). The Curse of Complacency. Aviation Pros. https://www.aviationpros.com/aircraft/maintenance-providers/mro/article/10381353/the-curse-of-complacency
