Turn onto xwind and final at 500' - why 500'?
 

Just was thinking on the way back from flying lessons the other day about why we make the turn from upwind to xwind at 500' and not at say 300' or 800'?

I should of asked him there and then, but is it correct to say that the reasons are that 500' gives the standard aeroplane enough time to get the best rate of climb speed and to check that we are tracking on a straight upwind?

And what about landing......why do we turn from base to final so that on final we are at 500'........why is there this general rule and how did they arrive at the number 500'?

Might seem like a pretty silly question, but I always like to know the reasons behind the theory or in this case the numbers!


Thanks all.........


MK

I've answered your same question elsewhere. It's considered bad form to cross post in these forums. How about deleting your copies?

quote:
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Oz rules specify that the turn after take-off must not be lower than 500'
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and at non-towered airports the first turn should be within 300 ft of circuit height (with one exception).

djpil,

manakim asked WHY the turns at 500'. We all know what is written in the books. I think the question why is a interesting one.

Does anyone know why, 'it is written' ?

Tinstaafl,

where did you answer manakims' question? I would like to read it.

Cheers, Z.

Hey guys,
Could it be something to do with the CAR Reg 157 - minimum height in flight of 500ft - with one of the exceptions being if taking off or on final approach....
Just a thought

Cheers

Good one whaet!

That sounds very logical to me. Quite unlike CASA regs to be like that!

Anyone else have any ideas?

Thanks, Z.

Nope, he asked "We" make the turn there coz of the rules. Same reason I try to drive on the left side of the road in this country. However, DFC has a good go at a rationale for some of the rules here. There are still only two reasons why I fly the approach in a Pitts the way I do - coz of the rule, and other traffic, if any.

Because its halfway between runway elevation and circuit height.
First 500' on Upwind, turn left, second 500' on Xwind, turn left, fly downwind etc...

Any higher or lower than 500' and the circuit dimensions get skewed, and you dont fly the 1 : 1.14 rectangle pattern.... which gives good circuit area for traffic separation, but keeps you close enough to make the runway if the hamster up front dies on downwind.

There is no good and valid reason that the 500' turn should be law. It should be a standard procedure, not law. There are times when it is not suitable.

When you are flying out bush (and I mean right out bush, not an ALA used by flying schools in farmland) and operating in a single with nowhere safe to forced land except the runway clearing behind you, take off and begin a climbing turn. This reduces the time you won't be able to make it around the 180 to land.

Is this legal? Probably not, but turning below 500' is sometimes safer. For some reason Australian aviation has incredibly restrictive laws (as opposed to procedures). Sadly this is to the detriment of safety and operation.

Hi people,

thanks for the replies.....its been an interesting read for me. From what can be read from people's replies, it is a combination of legal and practical/logical reasons why the turn at 500'.

But thinking about it.......when this rule was invented, pilots and authorities probably sat around when deciding on the height for this rule and decided on 500' for another reason which is that within the first 500', it gives the pilot enough time to establish the Vy or Vx attitude for climb, clean up the aircraft (flaps and ldg lear) whilst maintaining a lookout for other traffic. If a turn was allowed earlier, then un-necessary distractions could occur and maybe more incidents/accidents could be predicted.

MK.

Your reasons might be right re the bush lawyer who sat around thinking about how to put it into legislation to irritate pilots.

However, one can get permission for early right turns (I have forgetten the reg :confused: ) when twr is operational, so the argument for wrapping the pilots in cotton wool so they keep themselves out of some perceived trouble does not hold water.

As for when is a suitable time to turn, the pilot's ability and the complexity of the aircraft will dictate when the aircraft is tidied up to start turning.

Having said that, I do not mean flying like the C172 turn near the start of the 007 film "The Living Daylights"! Must be a 60deg AOB turn seconds after rotation with the wingtip about 1 foot off the deck :eek: .

Re: Turn onto xwind and final at 500' - why 500'?
 

I was never taught to turn at 500 feet. In fact I usually turn much higher, 600-700 feet and make a steeper approach. That way you aren't so dependent on the engine 'dragging' you in to the threshold, but using your altitude to glide. The only reasons I can think for teaching a 500 foot turn are that it makes the circuit simpler for students to remember and more symmetrical. YMMV.

Re: Turn onto xwind and final at 500' - why 500'?
 

Is there a correlation between the 500ft turn,a 3 degree glidepath and the expected touchdown point of the a/c????

One would think this altitude is/was designed to give the pilot the "normal approach"profile for landing....

On Departure,500ft would be sufficent to recover from a departure stall

Re: Turn onto xwind and final at 500' - why 500'?
 

I am curious...

Is there a reference for this? I am aware of the AIP entry to be inserted

from SUP H51/05, but is SHOULD a requirement or a suggestion? Or is there a CAR reference I have missed?

Re: Turn onto xwind and final at 500' - why 500'?
 

Final at 500'... simple maths generally at the correct circuit spacing for a 3 degree approach when considering a stabilised approach..... now whether this can be placed in practise is a different question.

Consider rolling onto final a 1.5 nm from the threshold.. that places you on the 3 degree profile at around 450'. NOW.. all well and good for an aircraft travelling at 120kts in the ciruits as this final segment will be convered in less then a minute howvere for your typical C152 this appraoch is a bit long winded... approax 2 min for this final leg which is kinda rediculous. I mean there is such a thing as a stabilised approach and then there are redicously stabilised appraoched that become unstable because it takes to long at a slow speed.

Now final will actually be a little less then 1.5nm as you conder the threshold at 50' and 1000' markers for your touchdown zone BUT once again people teach the threshold when the 4th centerline marker is about 1000' and 50' over the threshold. BUT practicle for a short field... not really... but why would you be going there in the first place if you are worried your aircraft will not pull up in time? All you single drivers out there just remember that alot of the higher performance singles will not make the runway.. even the lower performance ones will not make the runway.. so consider your aircraft type when considering the runway as an option in training (i'll get crucified for that comment).

I dont agree with people trying to teach airline profiles to someone who will be flying a cropduster in GA for 2000 hours BUT when they come accross higher performance aircraft this will surely come in handy....

As for turning crosswind at 500 and not before.... why not?... especailly as a abinitio pilot. As for the more experienced guys complaining... just remember expereince is just as dangerous as inexperience in many accidents.

Re: Turn onto xwind and final at 500' - why 500'?
 

From my experience of instructing in both NZ and the UK the 500' is just a function of the circuit height. I have used several airfields in the UK where circuit altitude is 1500 agl and therefore the turn onto x-wind and final is made at 800'. I would think that the general rule is that these turns are a function of half the circuit height i.e if circuit is 1000 then 500 is appropriate, it circuit is 1500' then 800 feet is the next appropriate level. This ensures that the circuit is evenly spaced and should allow glide back to the field should the donkey quit.

Re: Turn onto xwind and final at 500' - why 500'?
 

On behalf of brianh who is unable to post here.

Re: Turn onto xwind and final at 500' - why 500'?
 

so if im doing a 500ft circuit, or a 500ft departure (bungles) - which are all legal as far as i know, can i turn at 200ft?

Re: Turn onto xwind and final at 500' - why 500'?
 

I think CAR166 takes precedence here, unless terrain dicates an early turn onto x-wind or base. Again with low level circuits I was taught not to descend until on final.

Re: Turn onto xwind and final at 500' - why 500'?
 

Depends on Where You're Doing the Circuit

If you are not conducting legal low level ops such as training or aerial work in an approved area, (CAR's 141,. 157), then my understanding is that you cannot make turns below 500 ft as these constitute low flying. Yes, you can descend below 500 ft legally [I]on approach to land[I], where on approach means on final approach - not elsewhere.

So, if you were training at a CTAF/CTAFr, and making 500 ft circuits,then you should be 500 ft at the turn to x/w, and 500 ft at the turn onto final.

Once untrained pilots begin making 250 ft turns, or lower, then there is a very good chance of them suffering the wind illusion, and for this reason I'd recommend against it. If you do this stuff for a living, then the compensation is made instinctively. If you don't - then get some training in it first.

Yes, there is a certain logic about beginning your descent to land from the base turn, but I'd suggest that at lower levels, you should be flying a racetrack circuit - so that you make 180 degree turns from upwind to downwind, and a descending 180 from late downwind onto final. This pretty much ensures that you don't overshoot final, and it also keeps you 'in sight' of the threshold when in gloomy wx.Once you get down to 200 ft circuits, it must be racetrack or you can lose contact very quickly.

I'd therefore be thinking that the 'new' 500 ft circuit for light and slow aircraft is very likely to bring them onto final at the very same point as for the 1000 ft circuit. In practice it seems to be well inside the 'normal 1000' circuit, probably due to the lighties beginning a descent on the base leg rather than after turning final.

happy days,

Re: Turn onto xwind and final at 500' - why 500'?
 

Dont think this is the kind of thing that should come down to law.

In NZ we are taught not to make the first turn until after 500agl.... but it is not a law.

I think the grey area between law and practice needs to be as wide as possible.... and not just in aviation.

Standard procedure should not be on the same boundary as the law..... you need room to move.... Same in all aspects of life.

For some reason the law keeps re-adjusting itself to the norm, and the norm keeps having to be moved away from it... Once again, not just aviation Im talking about,

One day we wont fly anymore..... just stay at home in padded cells because its so much safer.:yuk: :yuk: :yuk:

Re: Turn onto xwind and final at 500' - why 500'?
 

The trouble is that if it isn't law, three things will happen.

1) You will never know what the guy in front of you in the circuit is going to do.

2) There will be more accidents caused by people emulating James Bond on takeoff.

3) There will be more accidents caused by unstabilised approaches.

As the saying goes, "rules are for the obedience of fools and the guidance of wise men" or whatever. As a student and as a low time pilot, I appreciate the existence of the rules because it helps reduce uncertainties - both in terms of expectations of what others are going to do, and what I myself am going to try and do, in other words, mental discipline.

For an idiot like me, starting a climbing turn at say 250 feet, while cycling gear up, setting climb MP, RPM, fuel pump off and engine instruments scan is asking for trouble. The 500 foot stipulation gives me TIME to get things done in an orderly manner - and then start the turn.

Same on final. I like the time to sort things out and make a mental decision about the stability of my approach. My decision to land is at 300 feet with a PUF check, carb heat off (if fitted), or go around.

I've done a few glide approaches where I've still been turning final at 100 feet or less, but that is under instruction.

Turning early after takeoff.
 

Sunfish,

The turn at 500 should be procedural, not mandated by law, except possibly in GAAPs/CTR. Yes it might lead to illusions in the inexperienced, but why do we need rules against it? Black hole approaches and Somatogravic Illusions (night) also catch out the inexperienced, but there are no laws against a new night VFR pilot flying out the back of Bourke.

There are circumstances where it is safer to turn prior to 500', but the law won't allow that. That I cannot get airborne in a single from an ALA in upper kumbutka west, and commence a gentle climbing turn to increase my chances of making it back if all goes quiet is ludicrous and a degredation of safety.

It should be up to the pilot to decide when it is safe to turn. You state that you are still getting the aircraft sorted at that height and you wouldn't turn prior. That is the normal thought process of a trained pilot. Such decision making should be part of the pilot's training.

One of the issues in Australian aviation is that there is a want to remove any form of decision making from the pilot; to have everything SOP'd and done to exacting spelt out procedures. That is fine for Airlines and some GA, but once you are out in the real bush, there are many other factors to consider and where it would be nice to be able to use our judgement without fear of transgressing some regulation. There are so many variables in remote area flying that are unquantifiable, and for that reason there should be fewer laws.

Re: Turn onto xwind and final at 500' - why 500'?
 

Just for interest's sake, the Concorde made its departure turn immediately airborne... makes for a pretty impressive takeoff! (in addition to the reheat and speed) ;)

Re: Turn onto xwind and final at 500' - why 500'?
 

compressor stall is absolutely right. Sunfish: I took a Cessna 150 out yesterday - takes over a minute to get to 500 ft on a warm day - plenty of time to read the POH to see what I need to do after take-off. Last time I launched off in a Pitts S-1-11B it took about ten seconds to get to 500 ft and I was ready to rock and roll. I'm not James Bond, just doing a steady climb at speed for best rate of climb.

Re: Turn onto xwind and final at 500' - why 500'?
 

I learnt that the reason was similar to what djpil earlier said.

Typically, on the climb out, and the late base, airspeeds are low. When you make a banked turn, stall speed increases.

The 500' is there to give you time to recover if you were to get into a stall or an incipient spin.

I also understand that at GA strips, or at an aerodrome without PAPI/VASIS, the idea is to get between a 4-5 degree approach, not 3 degree.

Then the other trivial reasons follow on from that, stucture, procedure, law etc.

Re: Turn onto xwind and final at 500' - why 500'?
 

Compressor Stall has it in one.

There is no way that we can possibly create a rule for every senario. Thats just crazy. Being an instructor myself I am sick and tired of students asking me for the answer to every senario. "what if this happens, what if that happens"

I can't tell them the answer all the time, there has to be a point where they start to apply what they've learnt and think outside the box as opposed to the robot attitude "The regs say this therefore they are correct in all situations" Wrong.

Now I've vented my spleen, wheres my beer!

Cheers
370

Re: Turn onto xwind and final at 500' - why 500'?
 

Sunsnapper,

!Think Compressor and Angels have you there. Too much regulation is crap! Pilots are trained to and have a responsibility to THINK and apply SOUND JUDGEMENT. There are many airports/situations/conditions where you WILL endanger yourself and the aircraft by complying with a min. 500ft turn after take-off. As Glekichi said it is not a law in NZ and we don't seem to have had your doomsday predictions dogging aviation over here!

Was this one old Dick's ideas? He made a nice impact with the turf at Harihari the other day-there were even reports of a small earthquake along most of the West Coast!:ok:

Re: Turn onto xwind and final at 500' - why 500'?
 

From what I've seen with instructor students 500 ft is not enough. One comment in the debrief - "Does it often do that?" "Nope, generally only once in your lifetime because if that happened turning final you would have hit the ground." The young lads generally swear at me once they realise that what they took for a clearing turn prior to a routine stall exercise had suddenly turned into the exercise that I'd briefed. Not uncommon to go around twice in the Cessna 150/152 before they manage to stop it.
I recall that the PPL/GFPT test form used to have a climbing, turning stall on it but removed now! I can remember doing it in my RPPL test many years ago. Some-one told me that it was not within flight manual limitations of the trainers - can't believe that. Be good for everyone to experience a stall from a skidding turn.

Re: Turn onto xwind and final at 500' - why 500'?
 

I don't think there's anything wrong with teaching a student to make those turns at 500 feet. It gives him/her something to focus on, at the very early stage when they need some form of guidance. After the trainee becomes a pilot and is, perhaps, placed in a situation similar to the one that stallie has been describing for the last few years ( :D ), the pilot should have enough training and education to be able to arrive at an appropriate command decision.

After all, isn't it all about survival out there? What price "command judgement" and "command decisions" these days? :ooh:

I'll complicate the issue even further now by saying that a newly minted CIR pilot can use a SID that requires a turn off RWY HDG at 400 feet AGL. How is this different to a VFR pilot, with similar flight hours turning at 500 feet? :confused:

Re: Turn onto xwind and final at 500' - why 500'?
 

In Ag' we can legally turn after T.O. at 200ft and fly a 500ft circuit at any aerodrome provided appropriate calls are made, however from an Ag' strip it's a whole different ball game.

Re: Turn onto xwind and final at 500' - why 500'?
 

DjPil, I'll never forget the "climbing turning stall" you made me do in the Decathlon! Hope to catch up soon.