Flying ILS Approach: Glass cockpits Vs Steam Gauges

Being an Instrument rated pilot and having flown both 'round dials' or 'Steam gauges'(C172) and glass cockpit(DA42) aircrafts, I was analysing what are the differences between the two/which is better. But sitting idle at home whilst preparing for job interviews, I decided to take this seriously to help me, keep in touch with the subject. Going by my background of being a software developer in my recent past, I would have a leaning towards glass cockpit.

To be honest, I was not very accurate with my ILS flying on glass cockpits as I was with steam gauges. I decided to dig deep, to understand my fallacy and concluded that ILS representation of glass cockpits, DO NOT enhance the Pilots experience of flying vis-a-vis Steam Gauges. It’s a very strong conclusion to make considering my software background and only over 50 hours of instrument flying (Actual aircraft and simulators) up my sleeve. Let me elaborate my view and would be happy to be proved right or otherwise. I could also be blamed as ‘making an excuse’ for being a lousy pilot 😆.

First let me explain ILS for all: ILS or Instrument Landing System is ground based instrument aimed at facilitating an aircraft to precisely be guided to the runway, specifying the direction and height to be followed. Aircrafts have instruments to read the data offered by the ground based equipment and these instruments guide pilot to fly left/right (Localiser Indicator) and Up/Down (GlideSlope Indicator). The aircraft equipment in older aircrafts was by a single instrument (round dial - ILS) and in newer aircrafts by modern software User Interface (UI) representation.

First the software approach: During my software development days, I was not well versed with UI front end development - however, here I am commenting on experts UI! From a software development perspective, the current representation of having a localiser needle associated with direction indicator and GlideSlope indication associated with the altimeter tape makes great sense. Wow! It meets the functional requirements - Yay! Let’s Implement! - Really?

Though it makes great sense and looks perfect on FRD documents, I don’t think it does meet the end user - Pilot's requirement - in terms of change or added complexity to the pilot’s actions.

Now Pilots perspective: During final approach, 1st task would be aligning directionally as directed by localiser then latching onto glideslope and descending as per profile. While descending, the actions of pilot, which differ with respect to both steam gauges and glass cockpits, that I am unhappy about and hence this rant.

During the final stages of descent, the pilot must scan the crucial instruments of Localiser, glideslope, altimeter and ASI besides a lookout for horizon/runway, approaching the decision altitude. The workload on Pilot is immense at this stage - his bodily organs/parts like eyes, ears, hands, feet, nervous system and brain have to process and act with utmost precision. 

In glass cockpits, the scan of instruments, as shown in the picture below of Garmin G1000 cockpit display, follows the pattern of GlideSlope(scan gathers more information like height and ROD too – In Image below represented as 1) then localiser (scan gathers more information of direction – In Image below represented as 2) then Speedtape(In Image below represented as 3) and finally the horizon looking out for Runway(In Image below represented as 4 but is actually beyond the image). The eyes follow a quadrilateral scan pattern (In Image below – 1to2to3to4and1). Even a minimalistic scan would need a scan of GlideSlope then Localiser and the horizon - here the eyes follow a triangular scan pattern (In Image below – 1to2to4and1).

In Steam Gauges, The scan of instruments in C172 traditional cockpit, The glideslope and localizer(In Image below represented as 1) are covered in single instrument scan, then a straight line scan to left towards altimeter(In Image below represented as 2) and ASI(speedometer, In Image below represented as 3) followed by horizon scan(In Image below represented as 4). The eyes follow a triangular scan pattern (1to2to3to4and1) instead of a quadrilateral scan pattern, because the need to scan DGI, is avoided with localiser needle incorporated in the ILS instrument along with GlideSlope needle.

Even if theoretical experts argue that I may be following a wrong scan pattern, practising pilots on steam gauges even just follow a straight line scan (In Image above 1to4and1) of ILS instrument and the horizon which is bare minimum scan. More tolerance towards varying behaviors should be considered while designing any product. In reality though the pilot flying would be following the straight line pattern, the Pilot monitoring does scan all the other instruments and calls out the necessary information.

The scan pattern differences, in my opinion, add to the complexity of brain processing as well as a few extra micro seconds of time required to perform the actions on glass cockpits. Careful experts of Human factors Ergonomics practitioners might see the merit in my argument and request them to conduct studies around the same and publish data along with findings.

Feel free to comment.

Notes:

1. The scan of all important AI, is not mentioned as the attitude for descent is finalized when established on glideslope and aircraft is trimmed in that position.

2. G1000 Image obtained online from the link: http://krepelka.com/fsweb/learningcenter/navigation/usingtheg1000.htm - a good learning source. Unfortunately could not find - ‘contact me’ address on the page.

3. C172 Image obtained online from the link: https://flyawaysimulation.com/media/images6/images/Panel-And-FDE-For-Default-Cessna-172SP-fsx2.jpg . Flyawaysimulation is a great place for simulator software downloads.

4. Please excuse my poor Paint skills😞.

Disclaimer:

As it’s a personal opinion of interest to pilots interaction with systems and scope of learning involved, It should not be viewed in legal or commercial angles.