Flight directors may cause more problems than they are designed to solve
Flight International 5-11 March 2013 has an editorial and and also an article by David Learmount on automation dependency. The editorial heading says "A decision by an airline several years ago to test empirically how pilots use flight instruments to monitor aircraft performance provided information that was unwelcome - and unexpected".
The editorial is then taken up at page 30 by David Learmount under the main heading "Dodging Disaster. Seems that after the Bournemouth close shave by the Thomson Airways 737 where the aircraft nearly went in during a go-around, the company arranged for eye tracking to be carried out in the 737 simulator to see how pilots scanned their flight instruments during a go-around.
According to the FI article, the investigation discovered that many pilots had a disorganised scan which frequently left out vital displays such as the airspeed indicator for critically long periods. Such a fundamental failure in the exercise of a skill which, it has always assumed, was basic to all licenced professional pilots was a shock, raising the question as to how widespread this failure is in the industry as a whole.
It would be interesting to know if these simulator go-around exercises were conducted using the flight director or were they done with the crews flying raw data?
Believe me there is a big difference in scanning between the two situations.
The very nature of flight directors require the pilot to concentrate squarely on the FD needles and normal flight instrument scan becomes practically non-existent. It is no wonder pilots instrument scan on the airspeed indicator and other flight instruments are "disorganised" when 99 percent of an airline pilot's flying in his career will be with reference to the flight director. That is dictated by company policy and recommended by the manufacturer.
The solution to the perceived problem of disorganised instrument scan is to encourage the switching off of the flight directors when not needed for critical parts of a flight. But manual flying would also be needed to keep current on basic instrument flying skills. Pilots scan would soon revert to that taught when they first learned to fly on instruments. The perceived danger involved with IMC go arounds would be a lot less. Flight directors are fine in most circumstances but have proved to be distracting during critical events such as low altitude go-around where trim changes and altitude captures require fast scanning of all the flight instruments - not just the flight director needles. Many pilots find it difficult to `look through` flight director needles in an attempt to see the little aeroplane symbol behind the FD needles.
Last edited by Tee Emm; 21st March 2013 at 08:10.