Where? + How? + When? + How much? + How fast? = the 5 Simple Keys to the Jacobson Flare

Where? + How? + When? + How much? + How fast? = the 5 Simple Keys to the Jacobson Flare

Our www.jacobsonflare.com home page describes The Jacobson Flare:

Precisely. In just 3 simple sentences:

1. The Jacobson Flare uses a logical, geometric visual ‘framework’ to guide the pilot from final approach to a perfect touchdown – in the right place.

2. This framework confirms to the pilot exactly what is happening at every stage, dispelling the myths that ‘trial and error‘, ‘developing a mental picture‘ and ‘feel‘ are the only ways to master the landing.

3. Since the development of The Jacobson Flare from 1985, pilots are presented with a fully-defined visual eye path, determined by the airplane type – making the landing safe, sure, simple and universal.

The page continues:

‘Accounting for all – even self-compensating for many – of the variable parameters that have distracted the attention of pilots away from the 5 essential elements of all landings: Where to aim; How to aim; When to flare; How much to flare; and How fast to flare?, the Jacobson Flare explains landings as never before.

Flown initially at a constant angle, the eye path translates to the classic exponential flare curve that generations of pilots have attempted to execute by judgment alone. The flare is initiated from a visual fix, derived from the cockpit lower visual cut-off angle (the lowest angle visible ‘over the nose’) and the flight path angle, offering a precise and visible model for both student and instructor.

The improvement in confidence, competence and progress of pilots – at all levels – is not only breathtaking: It’s consistent and it’s measurable.’

So far, so good, you say, but you are well entitled to ask: OK, but what’s so different from what I’ve just been taught?” … or … “Why would I need it?  I’ve been landing airplanes for 20/30/40 years?” These are fair questions but, in a truly honest moment: Do you fully understand, can you explain, can you determine how and why you can perform a ‘greaser’ of a  landing on most occasions and then a ‘howler’, the very next time? We can blame a gust or some inattention or distraction; but are these reasons, or just excuses?

 

DISCLAIMER:

The following material is descriptive, only, to provide a simple discussion to offer an initial understanding of the principles that underpin The Jacobson Flare. It is not intended to to provide flight instruction advice to individual readers. The fully comprehensive and illuminative description of The Jacobson Flare is contained and presented in The Jacobson Flare App (see further details, below).

 

Let’s take a simple look at the 5 simple pillars that underpin the Jacobson Flare: Where to aim; How to aim; When to flare; How much to flare; and How fast to flare? For these are the keys to understanding the vast differences from the conventional, non-standardised methods, that derive from the pioneering aviators of World War One, passed down without serious challenge or development, for over 100 years.

Where to aim?

Conventionally drawn, a final approach elevation profile diagram, published in text books and manuals, then depicted on whiteboards and flight training software, will usually display just one sloping line to depict the approach path angle. This line is generally never defined and these depictions never explain, or nominate the development of an aim point, let alone offering any method to calculate an appropriate aim point for every airplane type (size). This is critical, to assure runway threshold clearance by the landing gear, yet still maximise the landing distance available.

The minimum number of lines needed to depict the approach path profile is two: one line to represent the pilot’s eye path and a second – lower than and parallel with the first – to represent the main wheel path. It should be appreciated that the bigger the airplane, the deeper the aim point must be, in order for the main landing gear to clear the runway threshold safely.

The Jacobson Flare treatise starts with an understanding of the runway threshold landing gear clearance height, appropriate for the airplane type, projected down to a runway ‘impact point‘ (assuming, for the moment, no flare). The upper and parallel pilot’s eye path is projected down to a runway ‘aim point 1‘. The aim point 1 location, in relation to the runway threshold, is simply the sum of the distance to the impact point, plus the additional longitudinal distance from the impact point to the aim point 1. This latter distance is a simple function of the flightpath angle (usually the standard 3º), the vertical height of the pilot’s eyes above the main wheels and the horizontal distance from the pilot’s eye back (or forward, in a small tail-dragger) to the main wheels. It is not a complex calculation.

The Jacobson Flare App describes the method simply and factually.

How to aim?

If one can visualise the main wheel path as a virtual ‘wet concrete ramp‘ that we are trying to ‘roll‘ down, on the main wheels, it becomes very clear that using the elevators to control airspeed simply won’t achieve the aim: to leave a continuous ‘tyre tread impression‘, down the imagined ‘wet‘ surface. Pitching for airspeed results in a roller-coaster path that would oscillate all the way down the approach, necessitating constant changes in engine power/thrust and the imagined tyre impression would be in-and-out of the ‘wet‘ concrete. The threshold crossing height is inconsistent, resulting in differing height cues and erratic landing consequences. That is why it is essential to select a suitable aim point and then ‘fly our eyes‘ accurately towards that selected aim point on as straight a line as possible, using the elevators and controlling the airspeed with the throttle(s). That is to say, using the primary effects of the controls, instead of the secondary effects.  (The obvious and rare exception, these days, is when engine power is unavailable, such as in the case of total engine failure; this then becomes the subject of a non-normal forced landing procedure.) On most approaches flown today, reliable and variable power/thrust is a given. When the power or thrust value is fixed, such as on take-off, then airspeed is controlled with the elevators.

Flying a ‘path-based’ approach, rather than a ‘speed-based’ approach has several key advantages, the most important one being that it obviates the need to retrain pilots transitioning to more advanced operations:

It is vastly more stable – therefore much safer – than pitching up and down, chasing airspeed; a stable approach is essential – in any airplane.

The technique is equally applicable to both visual and instrument approaches;

The technique is standard and mandatory on heavier and/or high performance airplanes;

It minimises the two common student pilot errors of becoming ‘high and fast‘ or ‘low and slow‘ on final approach; and

It eliminates the need to ‘convert‘, at the worst possible time (the flare point) from flying a ‘speed descent‘ down final, to a ‘path descent‘ through the flare, to touchdown.

When to flare?

Historically, the decision on when to flare has been no better than an ‘educated guess‘ of vertical height, above the runway. The word ‘educated‘ is really no better than a euphemism for trial-and-error, repetition, judgment and experience, none of which can be taught; these each come at some indeterminate time, for each individual pilot. Some pilots take longer than others, in ‘getting the hang of it‘. Even after they first solo and consolidate their competency, it all starts again on, at the next airfield, or the next airplane conversion. Moreover, flare height is invisible to the pilot; without a radio altimeter and GPWS computer-generated height callouts, as in modern airliners (“100”, “50”, “40”, “30”, “20”, “10”), it can only be a subjective guess, the consistency of which wears off, anytime ‘absences from our comfort zones‘ occur.

Worse, the approach path angle depicted in just about all flight training books, manuals and briefings, is misrepresented, exaggerated at approximately 25-30º. The actual standard approach path angle is just 3º. This significant error, perpetuated for more than 100 years, has masked the fact that using a guess of vertical height to determine when to flare is further flawed, mathematically. A 3º path angle is a slope of about 1:20. This means that a 1ft error in that guess of flare height compounds x 20-times, longitudinally, along the runway.

Thankfully, triangles have had 3 sides for very long time and we can utilise the hitherto-unused third side, which happens to be the runway centre line. Not only is this side visible; it is, if sealed and painted, a calibrated ruler (with 100ft/30m centreline marks and spaces between). With the stable (and straight) pilots eye path and a second position line, projected at the lowest visible angle over the nose, from the pilot’s eye to the runway centreline, short of the aim point, an accurate visual fix can be derived, accommodating both the flight path angle and the appropriate flare height for the subject airplane. It is 400 times more accurate than a conventional guess of flare height, alone, because instead of the vertical height error compounding x 20-times, any longitudinal error diminishes x 20-times.

This vastly improved tolerance to error facilitates application of the Jacobson Flare fix to unsealed grass and gravel airstrips. It is without peer – any  longitudinal error in assessing the flare fix diminishes to a 1/20th error, vertically.

How much to flare?  

The ‘how much’ and ‘how fast’ to flare questions are closely inter-related, so it is useful to link them, to simplify the explanation of the landing flare manoeuvre. First, the Jacobson Flare does not reflect the conventional and misleading terms, ‘round-out‘ and ‘hold-off‘. In my 50-yrs’ experience, they confuse and misrepresent what we are meaning to achieve:

A pilot, attempting to ’round-out’ often achieves exactly that – pitching up too quickly and then ends up flying straight and level far too early and, as a direct result, too high above the landing surface. Complex corrections are then required.

The expression, ‘holding off’, misrepresents the aim, completely. The aim is really not to attempt to fly straight and level, as long as possible, as low as possible, swapping increasing angle-of-attack for decreasing airspeed (as I thought it was, for many years). The objective should be to execute a manoeuvre that transitions the flight path from a constant 3º path angle to the flare fix, to an exponential curving path that reduces both the flight path angle and rate of descent, each part-second throughout the flare, yet never actually reaches 0º or horizontal (except, perhaps, when executing a 3-point landing in a tail-dragger (tail-wheel landing gear configuration).

There is a actually a very simple answer to the ‘how much‘ question. We’ve done a great job flying an accurate eye path to the appropriate aim point, so why not utilise a second aim point and transition our line of sight progressively along the runway to that pre-determined point? On runways of approximately constant slope (not necessarily level), the optimum position to locate this aim point 2 is at the end of the runway centreline at the upwind (far) threshold. It is not the fence, or the horizon, but on the ground, at the far end of the runway. This will ensure that the final flight path angle is not level, but converges with the runway surface, at an optimal angle of approximately 0.5º.

If the landing surface is undulating, then a simple correction can be made, as follows:

Uphill landing zone: Select aim point 2 at the ‘top’ of the up-sloping landing zone, where it starts to level off; anything beyond this point is not usable.

Downhill landing zone: Select aim point 2 at the ‘bottom” of the down-sloping landing zone, where it starts to level off, to prevent a very deep touchdown.

How fast to flare?

The Jacobson Flare model utilises a 4-second flare (a simple, mental count of 1 .. 2 .. 3 .. 4” secs), through which the pilot transitions his/her line of sight  from the original aim point 1, to the supplementary aim point 2, usually at the upwind threshold, as described, above. Assuming that the Vapp airspeed is within limits (+/- 5kts) at the the flare point, the power or thrust is generally reduced towards idle, during the flare, as usual, with the throttle(s) fully closed just prior to touchdown.

The ‘4-second’ flare derives from actual observations, taken by the author, over no less a period than 30 years. From the moment that ANY pilot, in ANY airplane type, commences the flare, the average elapsed time through to touchdown was observed to be 5-6 seconds. Allowing 1-2 seconds for variables such as slightly excessive airspeed, control inputs or environmental factors, such as a wind gust, 3-4-seconds has been proved to be the optimal timing for the flare – for a normal landing – in ANY airplane type. (The 6 enhanced videos in the JF App Preview 190814 and in the JF App, clearly illustrate this point, in actual C172 and A380 airplanes and in B737-400 and B777-300ER full-flight simulators.)

By the end of the 4th second, the pilot’s line of sight should normally be ‘locked-on‘ to aim point 2, at the upwind threshold, with the throttle(s) closed. The airplane is now in a perfect position and attitude to touch down safely and smoothly – and in the right place: on, or very close to the original aim point 1.

Finally, it should be noted that this discussion has not been confined to any one type or class of airplane, for The Jacobson Flare is universal in its application.

Summary

To reiterate, the material above is descriptive, only, to provide a simple discussion to offer an initial understanding of the principles that underpin The Jacobson Flare. It is not intended to to provide flight instruction advice to individual readers.

You now have a better understanding of the 5 keys to The Jacobson Flare. How about a test drive?

The 6 enhanced videos in the JF App Preview 190814 (and in the JF App, itself) clearly illustrate The Jacobson Flare in practice – in actual C172 and A380 airplanes and in B737-400 and B777-300ER full-flight simulators. Similar videos could be produced for ANY airplane that is flared, to land.

The full, comprehensive and definitive description of The Jacobson Flare is contained and presented in The Jacobson Flare App (see further details, below).

 

 

Would you care to experience that unsurpassed sense of accomplishment, derived from executing consistently beautiful landings, more often?

Read what pilots of all levels of experience have to say about the Jacobson Flare technique and the App, on our Testimonials page.

Then download the COMPLETE Jacobson Flare app – for iOS or Android. You’re already possibly paying $300+/hour to hire an airplane : You’ll recover the cost of the app, in just ONE LESS-NEEDED CIRCUIT.

We invite you, also, to download our new, FREE companion app : the Jacobson Flare NEWS.

** NEW ** The Jacobson Flare Apps – for iOS

Download The Jacobson Flare for iOS devices now.

 

** NEW ** The Jacobson Flare Apps – for Android

Download The Jacobson Flare for Android now.

David Jacobson