Turn onto xwind and final at 500' - why 500'?
Thread Starter
Join Date: Jun 2005
Location: Australia
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
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 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
quote:
--------------------------------------------------------------------------------
Oz rules specify that the turn after take-off must not be lower than 500'
--------------------------------------------------------------------------------
and at non-towered airports the first turn should be within 300 ft of circuit height (with one exception).
--------------------------------------------------------------------------------
Oz rules specify that the turn after take-off must not be lower than 500'
--------------------------------------------------------------------------------
and at non-towered airports the first turn should be within 300 ft of circuit height (with one exception).
Last edited by djpil; 3rd Jan 2006 at 10:43.
Join Date: Mar 2004
Location: Perth
Posts: 214
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Join Date: Jan 2006
Location: Sydney
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
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
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
manakim asked WHY the turns at 500'.
why we make the turn
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.
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.
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.
Last edited by compressor stall; 1st Jan 2006 at 13:51.
Thread Starter
Join Date: Jun 2005
Location: Australia
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
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.
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
) 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
.
However, one can get permission for early right turns (I have forgetten the reg
) 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
.
Join Date: Apr 2004
Location: Fantasy Isthmus
Age: 51
Posts: 224
Likes: 0
Received 0 Likes
on
0 Posts
Re: Turn onto xwind and final at 500' - why 500'?
157 Low flying
(1) The pilot in command of an aircraft must not fly the aircraft over:
(a) any city, town or populous area at a height lower than 1,000 feet; or
(b) any other area at a height lower than 500 feet.
(1) The pilot in command of an aircraft must not fly the aircraft over:
(a) any city, town or populous area at a height lower than 1,000 feet; or
(b) any other area at a height lower than 500 feet.
(4) Subregulation (1) does not apply if:
(e) the aircraft is flying in the course of actually taking-off or landing at an aerodrome; or
(e) the aircraft is flying in the course of actually taking-off or landing at an aerodrome; or
166 Operation on and in the vicinity of an aerodrome
(1) The pilot in command of an aircraft which is being operated on or in the vicinity of an aerodrome shall:
(f) before landing, descend in a straight line commencing at such a distance from the perimeter of an aerodrome as is common to the ordinary course of navigation for the aircraft type concerned, the commencement of that straight line not being nearer the perimeter of an aerodrome than 500 metres; and
(g) after take-off, not alter heading from the take-off heading at a height less than 500 feet above the terrain, if the alteration was not:
(i) directed by air traffic control; or
(ii) necessary due to the terrain.
(1) The pilot in command of an aircraft which is being operated on or in the vicinity of an aerodrome shall:
(f) before landing, descend in a straight line commencing at such a distance from the perimeter of an aerodrome as is common to the ordinary course of navigation for the aircraft type concerned, the commencement of that straight line not being nearer the perimeter of an aerodrome than 500 metres; and
(g) after take-off, not alter heading from the take-off heading at a height less than 500 feet above the terrain, if the alteration was not:
(i) directed by air traffic control; or
(ii) necessary due to the terrain.
Join Date: Feb 2000
Location: with the porangi,s in Pohara
Age: 66
Posts: 983
Likes: 0
Received 0 Likes
on
0 Posts
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
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
Join Date: Feb 2004
Location: Melbourne
Posts: 120
Likes: 0
Received 0 Likes
on
0 Posts
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?
at non-towered airports the first turn must now be within 300 ft of circuit height
ENR 1.1 57.1.4 Pilots remaining in the circuit should climb to within 300FT of circuit height before turning crosswind
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.
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.
Join Date: Nov 1999
Location: The Land Downunder
Posts: 765
Likes: 0
Received 0 Likes
on
0 Posts
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.
No one has covered the most significant reason why the turn onto final should be by 500' minimum. It is because this turn is the regular cause of stall/spin accidents due to crossed controls in an overshoot past centreline while on base. The danger of crossed controls is exacerbated by the "proximity to ground" effect on pilot mindset, therefore the pilot tends to cross control to track back to centreline rather than make a steep turn near the ground.
500' minimum gives some small chance of recovery, and less chance of ground proximity illusion creating the problem in the first place.
Unfortunately, this situation is not well covered in most pilot training where stalls all seem to be at high altitudes and high nose attitudes and so many victims do not realise the onset until very late in real life, particularly as their eyes are outside the cockpit on the arrival threshold and they miss the fact that the ball is way out to one side and airspeed decreasing. It is well covered in Schiff, I think Vol 1 and is a renowned cause of arrival crashes and death in light aircraft..
500' minimum gives some small chance of recovery, and less chance of ground proximity illusion creating the problem in the first place.
Unfortunately, this situation is not well covered in most pilot training where stalls all seem to be at high altitudes and high nose attitudes and so many victims do not realise the onset until very late in real life, particularly as their eyes are outside the cockpit on the arrival threshold and they miss the fact that the ball is way out to one side and airspeed decreasing. It is well covered in Schiff, I think Vol 1 and is a renowned cause of arrival crashes and death in light aircraft..
Re: Turn onto xwind and final at 500' - why 500'?
at non-towered airports the first turn must should be within 300 ft of circuit height.
Join Date: Apr 2004
Location: Fantasy Isthmus
Age: 51
Posts: 224
Likes: 0
Received 0 Likes
on
0 Posts
Re: Turn onto xwind and final at 500' - why 500'?
Originally Posted by Dry_Twotter
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'?
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,
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,