Post from David Jacobson

‘We’ve always done it this way! … What’s wrong with that?’ – 13 November 2018

‘We’ve always done it this way! … What’s wrong with that?’ – 13 November 2018

“We’ve always done it this way.”

The ‘Law of Primacy’ in education is very powerful:  What we are first taught on any given subject often creates a strong, almost unshakable impression. We believe it, implicitly. Perhaps that’s why generations of flight instructors have resisted looking at landings in other way than the 100-year-old ‘conventional wisdom’: that pilots develop landing judgment and proficiency only by ultimately ‘getting the hang of it’, though repetition and practice. And again and again, on every subsequent aircraft conversion.

This is time-consuming and can be unnecessarily stressful and very expensive – for the student – and for the operator, in terms of wear and tear and damage to aircraft.

30 hours to first solo is not unusual. It is, however, unnecessary and quite harmful to a pilot’s confidence. If this sounds familiar, please read on.

When the elements of this ‘conventional wisdom’ are examined, they don’t stack up very well:

What’s wrong with conventional methods?

Simply stated,

  • Triangles have had 3 sides for a very long time.
  • We only ever used 2 of them – the hypotenuse for the pilot’s eye path (correct) – and the opposite side to guess the flare height for each type (highly inconsistent and mathematically flawed).
  • The opposite side (flare height) is invisible to the pilot (forgetting radio altitude call-outs); the conventional wisdom is to develop landing judgment by repetition and trial and error; this height changes with every aircraft conversion.
  • Because the final approach flight path angle (FPA) is exaggerated in books and manuals and all training aids and depicted at around 25-30°– instead of the normal – the actual FPA has been masked; 3° is near enough to a 1:20 gradient, a very flat gradient. The significance of this exaggeration is crucial:
  • It means that every vertical error in flare height judgment or control compounds, one way or the other along the runway, by 20 times  that vertical error.
  • Until the Jacobson Flare, no-one thought of using the 3rd side of the triangle: the adjacent side.
  • This is the runway centreline – effectively, a calibrated ruler (consistent centreline markings) and fully visible to the pilot (under most conditions and where not, options are available).
  • A visual fix (based on the RAF 617 Sqn ‘Dambusters’ operation of 1943) becomes available, using a ‘flare cut-off point’ on the runway centreline, short of the initial aim point, to identify the flare point, rather than a haphazard guess of flare height.
  • Any longitudinal error is reflected as only 1/20th, as a vertical error, making the technique extremely tolerant for use on grass and gravel airstrips, (without any central line calibration).
  • The Jacobson Flare addresses all aspects of the approach and landing, including where to aim; how to aim; the key difference – the use of a visual fix to identify the flare point, rather than a haphazard guess of flare height; how much to flare; and how fast to flare.

Captain David M Jacobson FRAeS MAP

The Jacobson Flare App for iPad

Simple, Unassailable Aerodynamic Logic