The flying skill was based on the T-scan & reference parameters

Scan patterns and human factor

The human factor behind pilots losing their flying skills is their instrument scan slowing down considerably. For the benefit of the millennial’s, there used to be an instrument scanning technique called the T-scan. Before the advent of the electronic displays, there was an emphasis on adopting a specific instrument scan pattern which formed the letter ‘T’. Ever since the advent of the electronic displays, it has ceased to exist.


Human factor behind basic Instrument Flying
T scan

There was no transition to a new scan pattern or mnemonics. The so-called loss of flying skill is attributable to the damage of a scan pattern and thus, loss of reference parameters. In fact, the reference parameters are no longer a part of flight training. Automation is now expected to maintain the settings with precision. The disconnect happens here.

Human factor behind T-Scan instrument scan pattern flow during ILS approach
Manual & Coupled ILS approach

Advantage of the “T” format

T-scan enabled the pilot, who was manually flying the aeroplane, to concentrate primarily on the major performance indicator – the attitude indicator (or artificial horizon) and scan out and back to the secondary instruments, such as
the speed and altitude.

Transition to electronic flight display

Humans generally do not like change especially human factors in the workplace. If they are set in their ways, there will be resistance. Primarily, the resistance is to accepting anything new especially if it involves the use of cognitive skills.

The aircraft back in the days had the cockpit crowded with instruments. There was a constant competition between the instruments and pilots gaze/attention. NASA did research on displays that could process the raw aircraft system and flight data into an integrated, easily understood picture
of the aircraft flight situation, culminating in a series of demonstration flights to demonstrate a full glass cockpit system.

NASA’s success led to glass cockpit work. Acceptance of electronic flight displays is reflected in the total. It begins with the introduction of the Boeing 767 in 1982. Safety and efficiency of flights have been increased with an improved pilot understanding of the aeroplane’s situation relative to its environment.

Scan pattern on the EFIS?

The standardised practice used around the globe was T-scan. Transition to the EFIS aircraft was full of challenges of the new concepts of instruments and the automation philosophy. In the process, neither was a new scan pattern developed nor was it taught during training.

Human factor in Radial scan pattern no EFIS equipped aircraft
Credit: flightliteracy

The objective of the scan in a radial pattern is to maximise the focus at the center. The most important flight parameter, the pitch. It is important for the pilot flying to scan the instruments but it is equally important for the co-pilot to scan the instrument. A French investigative authority study on approach and go around aircraft state awareness has stated that during go around in most of teh cases the co-pilot does not know where to look.

Human factor on EFIS aircraft scan pattern and dwell time
Dwell time & percentage (NASA 1981)

Airplane state awareness during go-around.

Trainers and training centers have stopped training pilots on this essential survival skill set.

mindFly analysis

A pilot is a pilot first and a cockpit manager later. Increasing automation has affected the flying skills of the pilots. First and foremost, the pilots have not been trained on the instrument scan pattern and reference flight parameters. The types of human factor include cognitive primarily function with emphasis on heuristics. Pilots make their thumb rules and develop scan patterns which help them increase the arousal factor.

Retina tracking is one of the means that a few airlines have incorporated in their training and feedback process. The gaze, blinking rate, retina dilation etc. give an accurate indication of what is going on in the pilot’s mind. After all the eyes are the gateway to the mind.

About Capt. Amit Singh

I think therefore I am Airlines Operations and Safety balance expert. A former head of operations/training and safety of successful LCC's in India. An experienced member of the startup teams of these airlines has hands-on experience in establishing airlines systems and processes.

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