Judging the turn onto downwind from midfield crosswind

[wwejosh]

Hello,
After recently starting my navigation training for the PPL, I have had some difficulty judging the turn onto downwind from midfield crosswind. I think the main issue is that the runway is directly behind me. I normally aim for a NM wide downwind spacing from the runway, using the wing strut as my main reference.
Does anyone have some suggestions for me to fix this?

Cheers

[Track5milefinal]

Pick an aim point before you cross the runway... works for me!

Ask your instructor thats what they're there for:ok:

[The Green Goblin]

The average lighty will be doing 100 knots overhead which is 1.7nm/min. For about a 3/4 of a mile downwind set the timer overhead and turn at about 25 seconds. You will do a lot more of this type of thing when you get into the IFR stuff. 25 seconds after abeam the landing threshhold turn base and this will give you a pretty good circuit.

GG

[Mstr Caution]

Or if no features available

1nm spacing will be achieved in 30 seconds at 120kts.

Turn earlier to account for radius of turn, maybe start at 20 seconds?

Consider the effect of wind as well.

edit: GG - Has beaten me too it regarding timing

[tinpis]

Ask the Doctor for a program for your GPS
Failing that I would try looking out the window :hmm:

[Oktas8]

When the leading edge of the tailplane is about to cross the runway, turn downwind.

It only works for single-engine light aircraft, but when you move on to bigger ones you'll have more experience at judging the turn.

[ForkTailedDrKiller]

The average lighty will be doing 100 knots overhead which is 1.7nm/min. For about a 3/4 of a mile downwind set the timer overhead and turn at about 25 seconds.

GG, you are kidding - right? Young fella doing PPL navs and you suggest he does timed circuits?

You will do a lot more of this type of thing when you get into the IFR stuff. 25 seconds after abeam the landing threshhold turn base and this will give you a pretty good circuit.

He will? I have renewal No. 23 coming up this year - and I have never done this!! I guess there is always something to learn.

1nm spacing will be achieved in 30 seconds at 120kts. Turn earlier to account for radius of turn, maybe start at 20 seconds?

Another joker!

Ask the Doctor for a program for your GPS

Sorry, don't have one. Hard to believe, I know. Don't think I ever look at the GPS (any of them) in the circuit.

It is interesting to look at the snail trails left on the GPS after an experienced pilot has been flying a few circuits - lines running right over the top of one another!

Its called judgement! Comes with that other mystery - experience!

Failing that I would try looking out the window

Got it in one Tinnie! Well, two if we ignore the GPS remark!

When the leading edge of the tailplane is about to cross the runway, turn downwind.

Bit tricky to do in a V-tail !!

http://www.fototime.com/738A7414EAD9493/standard.jpg

Dr :8

PS: Don't sweat it Josh. Its called judgement and it will come to you with time if you keep paying attention to your circuits. What does it matter if you fly one a bit tight (extend down wind if necessary) or a bit wide (provided you dont dip a toe into controlled airspace). Aim to get the next one right. When you arrive in a circuit with traffic you will need to be a bit flexible anyway!

[scardycap]

As Oktas8 said. As a former instructor I was taught and used to teach when the tailplane crossed the edge of the runway start your turn, works particularly well for night ops when you don't have any visible features.
Forget the timing stuff your taught how to judge on downwind with your wing strut, same technique applies using the tail.

When you start flying the biggies and you've got some time under your belt then you can get all fancy and do timed turns

[UnderneathTheRadar]

Two options for you:

1. When IFR guys are intercepting a DME arc, they use 1% of ground speed as the distance prior to the DME arc to start their 90degree turn. So, if you want to end up at 90 degrees to midfield crosswind (i.e. downwind) at DME 1NM (effectively) and you're doing 100kts, commence turning 100/100 = 1NM prior to your desired arc - or over the field.

2. I was told by a DC9 pilot that for IFR circling approaches where they arrived just visual overhead the field and at 90 degrees or so to the runway, the rule was to turn right (or left) 45 degrees and start the clock. After 45 seconds, this is your base position and commence a continuous turn to final. I've always been suspicious of his maths (at 180 knots this puts you almost 3NM from the field as you commence a base turn but not flying DC9s maybe this is where you want to be!) but have experimented and found it works nicely at 120 knots if you don't quite turn 45 degrees and wait only 30-40 seconds before making base turn - otherwise you end up too far on downwind for a good base turn position.



Neither of these will give you square circuits and may be over complicating it for a new PPL but it demonstrates that as well as judgement, maths can be of use in these situations.

Cheers,

UTR

[The Green Goblin]

Quote:
The average lighty will be doing 100 knots overhead which is 1.7nm/min. For about a 3/4 of a mile downwind set the timer overhead and turn at about 25 seconds.
GG, you are kidding - right? Young fella doing PPL navs and you suggest he does timed circuits?

Quote:
You will do a lot more of this type of thing when you get into the IFR stuff. 25 seconds after abeam the landing threshhold turn base and this will give you a pretty good circuit.
He will? I have renewal No. 23 coming up this year - and I have never done this!! I guess there is always something to learn.

How are you timing your outbound legs on reversals etc?

We use timed circuits in a Metro, but I don't think you would have to worry to much in a Bonanza doctor and neither did I when I flew them :ok:

[UnderneathTheRadar]

The average lighty will be doing 100 knots overhead which is 1.7nm/min. For about a 3/4 of a mile downwind set the timer overhead and turn at about 25 seconds.

Don't use this method - if you start a rate 1 turn at 25 seconds, where will you end up??!?! Not at 3/4 mile 'cause that's where you started......

[Mstr Caution]

S: Don't sweat it Josh. Its called judgement and it will come to you with time if you keep paying attention to your circuits. What does it matter if you fly one a bit tight (extend down wind if necessary) or a bit wide (provided you dont dip a toe into controlled airspace). Aim to get the next one right.


After 22 renewals I generally aim to get the first one right. Senior checks generally expect that too.

The Joker.

[kellykelpie]

I guess there is always something to learn.



I guess so.

[Lodown]

Does no one judge distance over the ground from altitude anymore?

I'm with Tinpis...look out the window. If you want to make it a semi- academic exercise. Cross the runway. Give it about 15-20 seconds and make the turn. If you're close to the runway, then either start your descent on downwind and plan for a continuous base turn onto final, or just aim a little wider on downwind to give yourself room. If you're too wide, then continue to the next aerodrome and call it a planned diversion. You'll get the hang of it.

In higher performance aircraft, that turn is a nice way to get rid of speed to get the gear out.

[Rojer Wilco]

I can't believe people are suggesting that a low hour VFR PPL use timed circuits or GPS mumbo-jumbo!

A little practice with visual cues such as tailplains, wingstruts or what ever floats your boat will go a long way. Ask the advice of an instructor whom is familiar with you, your ability and the aircraft you're flying.

I don't care who you are, what license or ratings you have or what you fly, if you've got VMC and you're in the circuit with others, your eyes should be outside as often as possible.

It doesn't matter if you don't nail the ideal downwind position. So you're a little wide or a little narrow... big deal. Practice and hour building will lead you to consistency.

[tinpis]

Roger
Very tongue in cheek :hmm:

http://www.pprune.org/5449689-post5.html

[ForkTailedDrKiller]

Very tongue in cheek http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/yeees.gif

:ok:

Dr :8

[OZBUSDRIVER]

Ahhh wwejosh, you suffer from the hardwired home circuit picture. unconciously you have the landmarks of your homestrip hardwired into your technique that now you have ventured away you do not have those subtle ques to help you.

Sweat not, as you blast across the top of the field on cross wind...have a look at the ground about where you think you would normally turn base..this is the bit you have been doing unconciously...then just judge your turn toward that landmark...at Reddo I just got fixated on either turning toward the canal estate for base 25**** or just prior to D-bay near a little inlet for 07 and first time I went away I got stuck until I made myself deliberately look for that point. Once you have turned downwind and after checks have a look as to how close or out you are and then adjust your base turn...it gets easier with practice. Forget about timing the turn, just get your eye in and that is all you will ever need:ok: By the time you come up for your flight with the ATO you will not even worry about it...you will just do it.:ok:

Teaching the position of the runway relative to an appendage differs from type to type when the "Look" of it always remains the same. You hold your head a certain way and you look down a certain way and if the picture looks right...it is right...if not, adjust it. It's not rocket science

****this was in the days before the PCs made us worry about aircraft noise and reddo was all left circuits...which created another problem the first time I did a right hand circuit.

[tinpis]

...then wait til yer first airline job in a 737 and ya see NOTHING

[TSIO540]

In my experience as an instructor, I've seen that pilots tend to struggle with 'judging' things because they don't have a specific technique or method by which to measure what is going on.

I don't think it really matters what techniques are suggested as long as they work and don't distract too much from safety.

wwejosh, how about you pick one or two techniques and have a crack at them until you get more used to judging distance from the air; and just see how they turn out?

[Mstr Caution]

Thread drift I know, but.

Around 25 years ago when taught how to calculate the distance of a potential landing sight for a precautionary search & landing.

One would do a lowish pass down the strip and count the seconds elapsed at a speed of 60kts or 30 metres per second.

At no time did I find counting or a quick glance at the second hand of my watch dangerous.

Therefore I wouldnt find it unreasonable to estimate a turn at whatever elapsed seconds after passing over the top of a runway on crosswind to distract from flying the aircraft or looking outside.

In the context of my first post, I opened with in the absence of visible cues or features. This might be related to night, reduced visibility, inability to see the runway behind you, a coastal strip where after passing over the runway the only cue is water or an isolated strip and limited ground features available. Maybe even a diversion or landing an an unfamiliar airport. Or,as experience daily the inability to see the runway in an aircraft with a wide flight deck or the inability to see any part of the fuselage or wings from the flight deck.

But as track5nmfinal said - Speak to your instructor.

[kellykelpie]

Someone posts that they are having trouble judging when to turn from crosswind onto downwind. Someone else posts that they might want to try timing to fix the problem - it is only a suggestion. I'm sure they have been told to look out the window. The suggestion of timing as one possible solution is surely better than putting it down to judgement and experience. Saying that is not very helpful IMHO. Maybe if he/she times a couple they might start to get an idea of what the correct picture looks like.

[bentleg]

Does anyone have some suggestions for me to fix this?


I had a look at the question while doing an entry to YWOL last night.

Yes, look out the window and when a modest distance past the runway start your turn. If you want a rule of thumb (unnecessary IMHO), try counting slowly to ten starting as you cross the runway, then turn.

In reality, I just glanced back and when a modest distance past the runway I turned. You can fix any overshoot or undershoot in the turn on downwind, when you can see the runway.

(I'm not an instructor, VFR for some years, recently IFR)

[bythenumbers]

PS and before all you IFR guys bombard me, I am an instructor and IFR rated



http://farm1.static.flickr.com/1/1131368_cae8cc9e38.jpg



Oh my lord...

[Runaway Gun]

If you want a mile spacing, simply look at the runway before you fly overhead. You should know it's length. 6000ft is close to a mile. Then just interpolate the distance to some features on the ground. Fly overhead them (and keep looking out for circuit traffic too).