Use of Flaps on Takeoff...?

[RadioSaigon]

OK, here's something for you guys who slavishly adhere to every word written in your AFM.

First, it's based on the BN-2 Islander which has been previously mentioned in this thread. It's slightly off-topic, but given that the discussion is now on the veracity of the AFM, it's still topical. These will be just a couple of examples I can think of that may illustrate the "less than complete" document the current AFM's have become. I don't have either an AFM or an Islander Pilots' Handbook to hand, so this is written entirely from memory -feel free to challenge my figures if you have the documentation to support your contentions.

First, the Islander AFM states the engine sump-capacity (Lycoming O-540's) to be 12 US quarts. That is a figure that is entirely accurate, but it doesn't tell the whole story.
Those engines will run happily anywhere between 6-10 quarts. If you have to, 4 quarts will not cause any problems for a short flight.

We had 2 Islanders, 2 Islander pilots, 1 each -a nice symmetry. The other pilot was also of the opinion that the AFM was infallible, sacrosanct.
Every day, religiously, 1st flight of the day, he'd top his sumps off to 12 quarts -then at every pause in operations have to spend substantial periods of time cleaning oil blown out of his engines off his cowls, legs and fuselage. So, every day he'd top those sumps off with 2 quarts each... that's 4 quarts every day going into the aircraft. He also flew the aircraft strictly in accordance with AFM figures. His cruise was never any better than 120KIAS. He pretty regularly cracked cylinders and his brake pads might last 50 hrs. His fuel burn never any less than 60lph.

My machine: I ran my sumps at no more than 8 quarts, very rarely had to add any between 50hr inspections and a quick wipe once or twice a day was as much as she needed. I expected (and got) 120KIAS cruise-climb and 140KIAS in the cruise. My engines went TBO+10% effortlessly with the engineeer pulling them down asking "what the hell are they doing out of the airframe?". Fuel burn averaged around 56lph. Yes, I did run the engines over-square -until about 6,000' AMSL anyway

At another place I was lucky enough to have a CP that had something around 5,000hrs in the BN-2. You could say he had some idea of what he was talking about -and incidentally was the guy that trained me. We worked together for about 5 years, during which time he trained quite a few pilots on the BN-2. I remember walking out of the hangar after putting my machine away for the day and seeing the CP get out of another (we had 4 at that place) looking rather pale after a training flight. I said something fairly cheeky to him, which I won't repeat here, which prompted him to ask me if I'd ever done a VMCA roll -which of course, at that point I hadn't. Apparently he'd pulled one on his candidate during the cruise, the candidate either hadn't realised or just brain-farted and kept pulling back-pressure to maintain his cruise level. The CP let him go to see how long it would take before he realised. Long story short, he didn't; she entered a VMCA roll and the CP recovered the aircraft. The candidate didn't get his rating. So off go the CP and I into the books to find the numbers for VMCA -nada. There was mention of VMCA, but no numbers. So after the discussion and research, we're still going "what-if"... so we hop into one, get plenty of altitude and discover that she'll enter VMCA roll 2-3KIAS before she'll stall whatever the configuration. Handy information to have, don't you think?

Yes, some of the places I've flown are a little more demanding than YSBK-YCNK-YSBK VFR and yes, I do listen to the people that have the experience I would like to have. If that makes me a "cowboy" -as it seems I have been tagged in another thread, then that is a tag I'll wear with pride. From what I can see, many "urban" pilots seem to perceive "country" pilots as cowboys -it strikes me that that may be because you have little if any idea of what we do, how we do it or why we do it. As I've said in other similar threads, none of us set out to cause harm to self, pax or airframe. Our best protections are knowledge, practice, professionalism, skill, care and attention -which must underpin every flight. Just because someone does things a little differently to the way you consider "proper" doesn't make them an idiot, a test pilot or any other disparaging tag you may care to hang on them. In many cases they are extremely thoughtful, careful, professional pilots that care enough to find out the information their AFM simply does not provide.

[RadioSaigon]

If there are any current Islander pilots following this thread, how many of you know why when fully Up, your flaps still have a 2-3deg 'droop'? Or why your elevtor trim-tab is split? These too are things you should know -but I'll guarantee they are not in your AFM.

[glekichi]

R.S.

Do you fly in Australia?

There seems to be a disproportionate number of those blind followers over here, and even more that are eager to criticise anyone who does things slightly different to them.

Oh to work for P.K again... if only GA paid better in NZ.

[RadioSaigon]

doing a little glekichi -and yup, you busted me

[Chesty Morgan]

The pilot in command (PIC) of an aircraft is the person aboard the aircraft who is ultimately responsible for its operation and safety during flight

The PIC must be legally certified (or otherwise authorized) to operate the aircraft for the specific flight and flight conditions

The PIC is the person legally in charge of the aircraft and its flight safety and operation, and would normally be the primary person liable for an infraction of any flight rule.

Serving as "Pilot in Command"
Under U.S. FAA FAR 91.3, "Responsibility and authority of the pilot in command", the FAA declares:[2]

(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.

(c) Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator.

ICAO and other countries equivalent rules are similar.

Especially interesting is FAR 91.3(b) which empowers the PIC to override any other regulation in an emergency, to take the safest course of action at his/her sole discretion. It essentially gives the PIC the final authority in any situation involving the safety of a flight, irrespective of any other laws or regulations.

You make your own mind up. But I would suggest that if you can't take off within the limitations of the POH and SOPs then you don't do it as it does not constitute an emergency.

Is the safest course of action to use a non standard flap setting ignoring all the numbers in the take off performance?

Just some food for thought.

[Joker 10]

Quantity of oil in sumps as justification for test flying, get a grip.

How about the Baron some years ago that took out all its passengers because the PIC on a flight to the Snow Fields for a weekend with his friends loaded aft of rear limit and over weight then took off burnt some fuel = aft Cof G lost control all lives lost.

Test pilot anyone ?????

[RadioSaigon]

Seems that I'm not the one in need of "getting a grip" Joker 10: nowhere have I said "ignore the AFM limits" as you seem to be implying with your crash example -quite the opposite in fact. remoak stated quite clearly that AFM limits must be adhered to -that's why they're called limits. Exceed them at your peril.

My examples are provided to illustrate my contention that whilst your AFM provides what may be termed factual information, it does not provide you with all the factual information. Challenge that, if you can.

A sensible pilot knows that and actively participates in the learning process. If you, Joker 10, want to stick your head in the sand, go hard. You are still not a pilot with whom I would choose to fly.

[remoak]

Actually it does rather make you wonder about how some of these guys are being trained. They are all talking like newly-minted PPLs, just repeating the mantra that their instructor told them and not bothering to think for themselves. In particular, it makes you wonder if the "stick-to-the-AFM-or-you-will-surely-die" crowd have ever even read their AFM and discovered just how much isn't in there.

What RadioSaigon is talking about is becoming intimately acquainted with your aircraft, as any craftsman would with his tools. Find out how it works, what it needs, what you can do with it and what you can't do with it. It has nothing to do with being a "test pilot", as you don't need to (and never should) go beyond any limit placed in the AFM. However, what he and I are both saying is that only a fraction of the information you need to operate safely and efficiently is found in the AFM, particularly the utterly inadequate AFMs found in most light aircraft.

At the end of the day, a C172 is an exceedingly simple machine, several orders of complexity simpler than virtually every car being made today. it is very, very difficult for any reasonably competent pilot to get into trouble in one unless you stall it at low level or exceed Vne in a dive. You would have to badly mishandle the aircraft to get into any trouble at all using the first two flap settings for takeoff. Going back to earlier in the thread, I have accidentally taken off in one with 40 degrees of flap and guess what, the experience was a non-event. Maybe if I had been able to raise the flaps all at once, I might have been able to stall it, but I doubt it. I'm not suggesting anyone should try it, I'm just saying that I've been there and it didn't hurt.

Also on the subject of flap settings in the C172, how many know that the reduction from 40 degrees of flap to 30 degrees was made, not for safety reasons, but in order to raise the MTOW to make the aircraft more attractive to buyers? So, if I were to find a C172 made before 1981 and re-enable the flaps to go to 40 degrees, I would be, according to Joker 10, a test pilot! But in actual fact, I would simply be doing what the aircraft was originally tested and certified to do. Of course, such an action is not allowed by the AFM, so I would surely die if I tried it...

We could talk more about how much of the AFM is written not from a safety standpoint, but from a commercial one; how conservative P-charts are; and how, often, the data in the AFM bears little relation to what was found in flight testing. But those who think that the AFM is a Holy Thing wouldn't be interested... and it is that inability to see beyond what is written in the book that is most worrying.

[RadioSaigon]

Originally Posted by remoak

...make you wonder about how some of these guys are being trained....just repeating the mantra that their instructor told them and not bothering to think for themselves....have ever even read their AFM and discovered just how much isn't in there.

I wonder if therein lies the answer?

I've been giving this whole thing a lot of thought over the last few days (too much time on my hands at present... but that's another story) and -at risk of perhaps displaying some preconceptions and prejudices of my own- wonder if the training system these newer people are being exposed to is entirely appropriate to the realities they'll face upon graduation?
My perception of the training facilities currently available -variously known as "pilot mills" or "sausage factories" or whatever you will- is that they train their candidates solely towards an airline career. This is in part at least driven by the airlines telling the trainers what they want in a candidate. Fair enough -but it ignores the fact that a 150-200hr candidate has (potentially) quite a few thousand hours to do in a totally different environment before the airlines will even consider looking at their CV.
So the trainers emphasise the importance of the comprehensive AFM's and QRH that the candidates may expect to be using in their airline careers -a dependence that is then ingrained and never questioned, carried into the 40+ year-old GA airframes upon which they'll build their experience and again never questioned, despite the sheer paucity of information available in those AFM's.
This issue is exacerbated by the fact of many of their instructors having been in industry only a matter of months longer than the candidates themselves, with no experience of the commercial realities of GA, and little experience of the airframes. The blind leading the blind.

If you read that carefully, you'll start to understand why I personally seek new experiences and challenges in my GA flying -but in doing so, 1st seek an instructor I know either personally or by personal recommendation with whom to train. I want the guy that has spent a lot of time thinking about what he's teaching and is able to impart knowledge not found in the AFM.

It disappoints me tremendously that people place so much faith in a poorly prepared document like the average GA AFM. The limitations section is the bible, the rest of it best taken with a large grain of salt, best thought of as the manufacturers' wish-list or what their lawyers tell them will provide the least exposure to frivolous suit.

Here's another one for the GA AFM bible-bashers: what sort of magnetos are on your engine(s) -do you know? Is it in your AFM? Is what's on your engine(s) the same as what your AFM says??? (You'll probably have to ask you LAME to get the good oil on that one). Do you have Slicks, Bendix, Shower of Sparks or something else? Which one's the impulse? What are your cold-wx, flat-battery start procedures (with no external power-source available) in terms of the mags that are actually on your aircraft? Do you know? Is it in your AFM? Does your engine have generator or alternator? What does your AFM tell you?

No, I'm not pulling these out of my arse and yes, I can provide the answers for aircraft I'm familiar with. Can you? I'll guarantee you'll have trouble providing empirical information and answers to those based on your AFM. For example, every Islander I've flown (there's been few) has told me in the AFM that the engines have generators -there's even a big 'ol light or 2 on the panel placarded 'generator'. Every Islander has had alternators. Same with the mags. Every AFM stated either Slicks or Bendix, impulse L only. Most of them have had Shower of Sparks -and yes it makes a huge difference when you're at a remote location trying to start an aircraft with a cold-soaked battery. You have to know what you have got!

I'll give you one of those very rare 'absolutes' in aviation that I mentioned several posts ago: your learning never stops; certainly not upon graduation with a bright & shiny CPL, certainly not at the back-cover of your AFM -it is not a complete document. Anyone that believes it to be so is seriously naive.

[john_tullamarine]

It appears that we should reflect on the differences between

(a) a Flight Manual - which prescribes essential information only and has little to do with the "how" of flying a particular machine .. and

(b) the Operating Manual (by whatever name it might be titled) - which gives OEM guidance information on the "how" of flying. As to whether this manual is exhaustive in its content is a moot point and varies greatly from example to example.

The GAMA style manual confuses the issue by having the flight manual embedded within the operating manual .. bits are (typically) FAA-approved and associated with the certification while the bulk is OEM generated.

[Double Wasp]

I know I am wading into this discussion in the late stages of it however I have to agree with remoak and RS on this. I have seen it too many times training people and flying the line with them that people follow their SOP's blindly as well as their AFM's. The documents can not cover all situations, it would be impossible to do so. While 99% of the time they are right there are occasions where they are not the right way to do things, and not recognising when those situations are is equally if not more dangerous.

If there is only one way to operate an airplane why would CASA authorize different Operations Manuals for different operators. The POH is a general guide to operate an airplane but as previously stated there is a lot left out. The limitations are as previously stated, limits, but P charts are full of padding and there are different operational situations not covered under these charts where the aircraft can operate safely. Unfortunately the average private individual does not have the benefit of an operations department behind them and they have to use their better judgment. Some judgments are better that others however.


What I would like to see is pilots that learn their aircraft, learn their SOP's and then look logically how their procedures are constructed. See under what conditions they are based on and what the logical outcomes are for them. If you understand this process for the standard situation you can use the same logic, in most cases, for the non standard ones.


Lastly for anyone who doesn't think the "popping" of a notch of flaps doesn't work they obviously haven't flown out of a truly soft strip or on floats in an airplane at max weight on "glassy" water.

Now lets hear what the experts have to say...
DW

[remoak]

To follow on from that, here's something that every pilot should do.

1. Book an aircraft for an hour, and find the P-chart takeoff distance required for the aircraft you are flying.
2. If you are flying from a relatively quiet place, place a marker at the point by the side of the runway which equates to the P-chart takeoff figure - sandbag wrapped in a hi-viz vest or whatever. If you can't do that, work out how many runway lights have to pass by before you get to that point - centreline lights should be 15m apart (probably different in Oz, everything else is).
3. Do a series of takeoffs - standard technique, short-field technique, and if you are really really brave and the feds aren't looking, you could try using flaps. I promise you won't die. If you are really really really brave you could try using a second flap setting.
4 Compare the book figure with the actual distances you achieve.

Every pilot should do this because it is the ONLY WAY you will ever know what the performance of your aircraft really is.

If you don't better the P-chart figures by at least 30% I will be truly amazed.

P-charts are great for PPLs who don't want to have to think about performance, but if you tried to use them for commercial ops, you would probably never go anywhere.

[Joker 10]

Radio Saigon Likewise I certainly don't want you in command of anything that flies if I am in it !!

Having had 46 incident free years since 1st licenced and an ATP I certainly don't need to experience home grown test pilots.

[FGD135]

Joker 10,

I am not acquainted with RadioSaigon, but from his apparent approach to his flying and his machine, I would suspect that I would have no objection to him being the pilot of an aircraft on which I was a passenger.

But you, however, with your blinkered views, would cause me some concern, should an unusual situation (something requiring the possession and confident application of knowledge) arise.

I am curious as to just what you mean by "test pilot". To me, a test pilot is somebody that flies an aircraft before it has been certificated - and before the AFM has been written.

I once chose to takeoff - in a piston twin - with FULL flap. The field wasn't short but was particularly rough, with patches of deep mud. I knew that I would be in trouble should an engine fail immediately after lift off, but the overwhelmingly important consideration was for getting the weight off the wheels as rapidly and effectively as possible - and for a short takeoff roll. (Commercial considerations precluded repair of the strip, or for waiting a few days).

Was I a "test pilot" for that takeoff? I don't believe so, as I wasn't doing anything the aircraft hadn't been certificated to do.

Of course, there was no published takeoff data for a full flaps takeoff, but this doesn't mean the takeoff was somehow "illegal".

Only if the AFM had expressly forbidden it would it have been illegal. You can't break a law that doesn't exist.

How about the Baron some years ago that took out all its passengers because the PIC ... ... Test pilot anyone ?????

That accident was the result of simple incompetence. I don't see the relevance to "test pilot". I wonder if you know the difference between error, incompetence, disobeyance of the AFM, and the doing of something for which there is no, or poor, guidance in the AFM?

A great many pilots don't possess the aeronautical knowledge they should. Many of these tend to "hide behind" the AFM as a way of masking their lack of knowledge.

How's your knowledge? We know that flaps increase lift but also drag. What sort of drag would that be? (i.e parasite drag, form drag, skin friction). You don't have to name it - just a brief rundown of how it happens will suffice.

Here's another question. Should you use the flaps to give drag assistance in a descent? What if you were in a piston aircraft, approaching the aerodrome to land, but thanks to ATC, now found yourself in a postion where a much steeper than normal descent was required?

Would you use flaps and/or undercarriage to assist the descent? I doubt the AFM would have any guidance for that situation.

What about if you needed to fly as slowly as possible? Any guidance in the AFM? Would you be a "test pilot" if you extended the flaps?

remoak,
Always a pleasure to read your posts. Yours is truly a voice of great wisdom and experience - a pity that others here cannot see that. I - and many others, I'm sure - greatly appreciate the time and effort you have put into this thread.

[remoak]

FGD135

Many thanks for the kind words... but what I really like is this:

Only if the AFM had expressly forbidden it would it have been illegal. You can't break a law that doesn't exist.

Precisely, and that is what RadioSaigon and I are saying. There is stuff the AFM forbids, and stuff it tells you how to do, but between those two points there is a vast gulf of information that makes no appearance whatsoever in the AFM. Your examples are particularly pertinent - many thanks.

Another point you made that is worth thinking about is what a "test pilot" actually does - which is to take a machine with unknown flight characteristics and find out what happens when you fly it towards it's limits. Every conceivable manoeuvre is covered during certification, including aeros and other unusual manoeuvres. You can bet your boots that anything particularly dangerous about the flight characteristics of a particular aircraft would result in a big red "DO NOT..." in the AFM. It is almost inconceivable that the average pilot could do anything with the aircraft that had already not been done during certification testing. The lack of info in the average AFM is frustrating, but it is not a prohibition unless specifically stated as such.

[Dog One]

Tell us, FGD135, in contemplating the full flap take-off, you took into account the OEI performance of the aircraft. No doubt, in your endorsement training on the type, your instructor had demonstrated an engine failure with the aircraft configured with full flap, gear down, max t/off power and speed at V lift off. Was this why you felt confident in attempting the take-off?

[FGD135]

Tell us, FGD135, in contemplating the full flap take-off, you took into account the OEI performance ... Was this why you felt confident in attempting the take-off?

Perhaps you had difficulty reading my post. This is what I said about the OEI possibility:

I knew that I would be in trouble should an engine fail immediately after lift off ...

[Joker 10]

There is a real danger that young inexperienced pilots developing their operating style will read this and believe it is OK to ignore the POH/AFM and experiment.

The training for a Test Pilot approval is rigorous and exacting, testing is flown to very disciplined planning and engineering/areodynamic expert approvals.

It would be tragic if someone really believed some of the scribblings in this thread, went out and tried and came unstuck.

Inculcating bad habits early in the development of skills inevitably leads to bad things happening sooner or later.

The old wise folk are generally conservative people who don't take unnecessary risk to see what might happen.

Experimentation is an uncertain science and there is no way every experiment will work, to fool around whilst close to the ground in the slow phases of flight essentially totally dependent on 100% power plant delivery is fraught with to many things that can go wrong.

Are the POH/AFM complet documents, no they are not, but they do take into account differing skill levels ( as opposed to the skill of the test pilot team certifying the aircraft), ageing of airframes, the fact that the powerplant is not always capable of 100% rated power.

The manual / handbooks job is to keep us all alive, to suggest that one ignores parts of it or re writes it to ones own criteria is just not smart.

[remoak]

Joker 10

There is a real danger that young inexperienced pilots developing their operating style will read this and believe it is OK to ignore the POH/AFM and experiment.

That's right... which is why NOBODY is suggesting they do so. Why don't you open your eyes a bit and read what is written, rather than jumping to ill-informed conclusions? As we have said... many times... if the AFM prohibits it, you shouldn't do it. If the AFM doesn't specify one way or the other, there is NO SUCH PROHIBITION, either in law or in fact.

And I really hope that young, inexperienced pilots DO read this, and DO decide to get to know their aircraft properly in a controlled and safe environment. Nothing being suggested in this thread will put them at any risk whatsoever, assuming they apply basic airmanship principles.

Inculcating bad habits early in the development of skills inevitably leads to bad things happening sooner or later.

And a refusal to learn how your aircraft performs in the real world has a similar effect, usually when the weather is bad and the pressure is on.

The old wise folk are generally conservative people who don't take unnecessary risk to see what might happen.

Every time you step into an aircraft you are taking an "unnecessary risk". You reduce that risk by knowing your aircraft intimately and ensuring that you know what it can (and can't) do.

Experimentation is an uncertain science and there is no way every experiment will work, to fool around whilst close to the ground in the slow phases of flight essentially totally dependent on 100% power plant delivery is fraught with to many things that can go wrong.

That is so brainless a statement as to be almost amusing. There is very little that is uncertain about taking off with differing flap settings. You know what your stall speed will be (or at least the maximum value that it will be), there are no CG or weight issues to consider, and the very worst that can happen is that you may have to close the throttle and re-land. Luckily, you will be closer to a landing configuration than if you had taken off with zero flap and experienced an engine failure, with a lower stall speed and a lower nose attitude, so in every measurable way you are safer taking off with more than zero flap. As we know that we are exploring performance, we will always be ready to get the nose down and maintain flying speed, right? And before you start bleating on about the dangers of re-landing, I have already stated that you should only do this on a nice long runway.

The manual / handbooks job is to keep us all alive, to suggest that one ignores parts of it or re writes it to ones own criteria is just not smart.

Another utterly brainless statement. The only reason the POH/AFM exists is to satisfy a certification and regulatory requirement, and to cover the manufacturers arse. In many ways it is no different to a placard in the cockpit. You would be amazed at how these documents differ in different countries, under different regulatory systems.

But more to the point, you have once again completely twisted what is being said here. Nobody is suggesting ignoring the POH/AFM, or re-writing it. We are suggesting filling in the gaps that these documents leave in our knowledge.

If you want to continue flying with the degree of ignorance of your aircraft's performance that you clearly aspire to, then be my guest... but it is neither smart nor safe to do so.

Dog One

No doubt, in your endorsement training on the type, your instructor had demonstrated an engine failure with the aircraft configured with full flap, gear down, max t/off power and speed at V lift off. Was this why you felt confident in attempting the take-off?

I can't speak for FGD135, but in most multi training, just such a manoeuver is demonstrated and taught - it is called an engine-out go-around or baulked landing. Maybe it isn't taught in Australia, but it is in NZ, Europe and the USA. Admittedly it isn't done at "V lift off", which isn't actually a real V-speed in any case. If the failure happened at Vr (which is what you are really talking about, and on which performance figures are based), you just close the throttles and hit the brakes. In the case FGD was talking about, you would stop pretty quickly. It doesn't really matter as the difference between Vr and Vref is minimal in any case(by design).

Again, I can't speak for FGD135, but if it was me, I would have accepted the possibility, before departure, that if an engine failed I may have land straight ahead. That is, in any case, true of many light twins if they are anywhere near their gross weight (ie the Apache, Aztec, and other older twins would fall into that category).

All flying is a risk, it is how you manage the risk that determines your skill as a pilot.

[Joker 10]

So now we are in our FAR 23 certified twin doing full flap takeoffs and we suddenly lose one engine and we are now into a ful flap demonstration of how to avoid a VMCA incident with max drag , low airspeed close to the ground and only 2 hands to complete all the drills, fly the aircraft and stay alive.

FAR 23 was never intended to certify for this, good idea to read the FAR.

The coroner in W.A. recently dealt with an incident/accident involving a FAR 23 twin flown by a very experienced pilot who lost an engine shortly after takeoff in conditions with a relatively high density altitude, the aircraft crashed parallel to the runway trying to make it back, the takeoff was in accord with the AFM flapless, the engine lost a fuel pump and quit, the aircraft was within W/B limits but close to gross.

There are 2 certain ways to meet the Coroner, one as a witness the other as the subject of the Inquest, neither way is good.

If one takes a position say to advocate experimenting with flap in the takeoff phase and then one really doesn't want to lose the argument by way of reason then one descends into specious reason to defend one's position.

Yes most of this thread has said one should read and indeed understand the AFM/POH but then in part by a number of posters the position is put that if the AFM/POH is silent on a point it can be read as that might be acceptable to experiment with because the author/certifying authority has not prohibited the activity on which the AFM/POH is silent. This legally a very difficult position.

One can only assume that part of a professional pilots training would be an understanding of the limits of the various levels of certification and how those limits are applied in day to day operation, FAR 23 is very restricted.