by | 2020-05-09

Paradigms or changing the way you see the environment.

This not about the loose change in your pocket. Paradigms are about ones narrow view of the world. They are the basis of systemic stagnation. The last place one wants to hear about paradigms is in the flight deck.

Cockpit resource management

Understanding paradigms and their influences and/or consequences is much of a cornerstone on the construction of sound CRM (cockpit resource management). I have been teaching CRM for quite a while so one figures I could be exempt from the ailing of paradigms. No such bonus exists for this instructor. I suppose perfection can never be attained unless spending enormous, read here disproportional, amount of time to get past 90% of said perfection.

Warning: if all you care about when flying is push-pull, slam, bang operation and what a beautiful sunset we have for landing … « Here is my selfie to prove it ». Take a break from this article. Others read on.

What the heck am I talking about? Well, first thing, a paradigm according to Webster dictionary is an example or a pattern. One can safely say that a paradigm is a functioning model with which the human brain functions. 

  • « Over the last 15 years, I have always operated into this airport this way. I am not about to change the operation ».
  • « New hires don’t have a clue ».
  • « If it ain’t broke, don’t fix it »… (a favourite of mine).


As pilots, we are required to employ rigorous discipline to fly safely. Rigorous discipline encompasses procedures, SOPs and certainly the memory of past experience (perhaps not so joyous) to avoid tunnelling ourselves into traps. So one may find excusable the three previous statements. Traps can be of all size. Much like the fabled James Reason model we use in basic CRM, the holes/traps can vary in geometry. 

Experience is a great instructor. Yet sometimes it can lead you the path of paradigms. Been there, done that? Anyone? 

I realize I am getting heavy on human factors theory. But here is my little story of getting caught in an « innocent » paradigm. For all sorts of reasons to be explained, it took me quite a while to realize the issue.

In a recent article, I was writing about a major refurbishing of the PA-30. Part of the project was replacing the venerable vacuum gyros with a set of Garmin G5s. Perhaps I am guilty of getting 330 home sick. Regardless, an « EFIS » is a nice way to help accurate flying. 

Be assured, on the other hand, that handflying anything with merely a stick and rudder (including that 330 mentioned earlier) is also my cup of tea. There is nothing like flying a conventional landing gear classic or glider with one’s seat of the pants and good total energy variometer (of course). 

I digress…

The long way to a paradigm

So back to this G5 thing set up in a PA-30 with some background info. Hey, paradigms require a lot of effort and reflection to ingrain itself into your flying life. It is worth explaining! 

The PA-30 is an old lady, yet the unsung heroine of the « well ahead of its time » category. A compromise for « fast » economical cruise you get a not so great manoeuvring or sightseeing visibility. The very docile 1G stall characteristic is superb but you do not get STOL performance at landing with 27 degrees of full flaps. 

Prior to acquiring the aircraft, I researched copiously on the aircraft and found that most owners/pilots found the aircraft to be on flare quite a floater. « Evidently », the contributing factors are a very clean laminar flow wing, not much flaps and quite a nose up stance required to maintain 3 points. This last point does fool the pilot to an extent during landing, negating a good complete flare (more floating) just to get the nose up to add that desirable drag in the process.

So this acquired « knowledge », let’s name it paradigm first phase contributed to a first impression of a floating aircraft. That was and still is fine in my book. The PA-30 is presently complying remarkably with personal major bucket lists items as far as destinations are concerned.

The paradigm second phase is more subtle. It fitted so well with the whole concept that it is worth our attention. 

Paradigms perhaps part of history

In the late 60s the PA-30 got some rather bad reviews when a sudden rash of stall, spin, crash accidents stained its reputation. Keep in mind the context: late 1960s. Considering all the knowledge we have acquired in the industry since then our view can be biased. Nonetheless, because of FAA requirements flying schools and a slew of operators started practising single engine stalls and Vmc (minimum control speed single engine) demonstration at close to 2000 – 3000 feet AGL. Really. The aircraft at 3300 pounds (not the max gross weight) will stall at 63 KIAS (clean) and Vmc being around 69 KIAS at those altitudes. Unlike late models light twins, this aircraft will snap on one engine in a way to make an Extra 300 pilot jealous (just a colourful metaphor here, please indulge me). Modern designs have the Vmc lower than the stall speed. You will technically stall the aircraft before the live engine will take you for a ride. 

Aerodynamically speaking there was no big surprise. There was no design flaw in the aircraft. But the FAA decided in an effort to reduce divots around airports to increase Vmc by 8 knots along with dire warnings and expensive airspeed indicators scale mods. Piper, to calm the situation even produced an « airflow kit » to improve low speed manoeuvring characteristics (without the possibility to maintain original and true Vmc). They eventually produced counter-rotating engines, thus eliminating this condition.

The classical approach speed for most general aviation aircraft is about 1,3 Vs. No problem, except that kind of speed got you « dangerously » too close yet to that new Vmc. So let’s add 5 knots here to be sure plus the wind. Yicks, now you got yourself a real floating machine as stall speed remained unchanged by paperwork, no kidding!

If you have questions about Vmc calculations used for certification purpose, do not hesitate to contact me.

A US Navy study on pilot experience and proficiency states that 500 hours are a minimum in order to reach good competence on any new aircraft on your licence.  It does not matter how much experience you log book declares.

Always learning

Being well aware of this fact, keep in mind that I teach this stuff, I have so far always flown very nimbly this light twin. So what if its floats? I am not running a DHC-6 operation in the arctic here, only flying out of « long » runways. Yet, even while making maximum effort braking for landing, meeting the POH section 6 numbers was very difficult.

Dear reader, if you held on right up to this point, this is where this paradigm thing was observed.


The G5s provide very accurate air data. Sure enough on the inauguration flight, pardon test flight, « the » snag made itself observable.

While on climb out (clear day) there was an airspeed discrepancy of about 6 to 7 knots between the legacy IAS and the new guy (G5). The « old » one was showing slow in reference to the new. In cruise 4 to 5 knots difference. And on approach the discrepancy got wider by 8 to 9 knots.

So far from what I saw, I was hoping to fly an approach at about 75 to 80 KIAS calm conditions but in reality according to the new IAS I was in effect flying at least 83 to 88 KIAS near the threshold. Having enough spreed was a safe understatement. While testing stalls the old IAS was off the clock nowhere to be useful. Yet the G5 was bang on when the NACA 642A215 said: « thats it ». 

So, it never occurred to this pilot during the whole time prior installing the G5 and flying happy as a clam and floating like a magic carpet to cross-check the groundspeed on the GPS! Done that all my career on jets, yet it never crossed my mind to question deeper this floating thing. It was a given due to what was acquired during « phase 1 ». The (fortunately) not so fatal trap was laid, I knew the aircraft floated and I accepted the fact.

I got the IAS indicator sent to overhaul. By the way, it was last done 13 years before! Would it not be great that auto parts or home appliances to be that reliable? According to the AME, airspeed indicators equipped with a TAS scale selector like the one on this PA-30 are prone to leaks.

Evidence strikes back

The newly overhauled instrument was re-installed. Both the static and dynamic tubing tested for leaks. Like a sore thumb hit by a rogue hammer, authentic airspeed revealed itself along with bells and trumpets! The aircraft on approach became a totally new machine. Landing on the numbers with a normal GA aircraft flare. No effort braking humbly meeting better than the book landing performance, GPS data to confirm. I had to wonder: what was I doing all that time?

Paradigm: the model was set. I never taught of checking further or even checking the GPS groundspeed. Heck, all this was safe albeit a bit funky. Counter arguments can be heard from here. All the guy had to do is fly the G5 and forget about the analog airspeed. Why even bother trying to fly with the old instrument? Accident reports are ripe with situations where pilots are flying with non MEL items unserviceable. 

Finally, a word of caution: there is a remarkable difference between paradigms and time proven or manufacturer issued procedures. My experience and knowledge require flying proper procedures in this case, for what was an unreliable airspeed condition. In this personal anecdote despite the fact that when the G5s were installed and certainly showing accurate air data on approach, the brain was unable to fly the proper approach speed shown on the G5. You ask me why? Well during the course of flight (3 simulated IFR approaches in clear conditions) I was indeed exposed to an unreliable airspeed condition. I did not even feel good to tickle lower speeds – near Vs – on approach with arguably false airspeed information. By doing so, I was wilfully avoiding a known risk. Flying conservatively the old IAS indicator was the proper thing to do. Many accidents occur with airspeed unreliability issues.

When the proverbial hits the fan, stick with SOPs, procedures and checklists and always take time to think outside the sandbox.

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