GPS altitude and circuits

[Hildy]

Folks, have a look at what Hildy said in his first post. "If you look at the track side-on in google earth...". He isn't using GPS to as a navigation tool in the circuit, he's using it to review his flight performance back home in the comfort of his computer chair. I did (and still do) exactly the same thing with a small portable GPS recorder that sits tucked out of the way, silently remembering what I've done. When I was learning circuits, it taught me that those nice 90deg turns were anything but, and these days I still review every flight later that night for track and altitude accuracy.

 

Hildy, the most likely reason that your altitude track doesn't look as expected is that the GPS will be 'smoothing' the recorded path - it assumes that a sudden change in direction (ie no longer descending) must be wrong, and so it continues your downward path for a little while. You may be able to remove the smoothing if you dig around in the configuration of the GPS or in the program that you use to upload the data, but I wouldn't worry too much. You know with much more accuracy whether you hit the ground hard or rounded out too high than any GPS recorder ever will.

 

(p.s. I just looked at your track. Given that I can see where you wandered around in the instructors office and when you did the pre-flight check, I'm guessing you were using a sports gps watch. Right? :thumb_up:)

I'm not a he, and I'm using a Garmin phone, but other than that, what you've said is exactly right!

 

I'm not up to landings yet - this was my first lesson that wasn't a TIF. What I was trying to work out was how much variability in height I had over the runway, and how high above the runway I was flying. At first I thought the altitude readings were wrong, and I should compensate using the altitude of ground level, but when I looked into it further, I saw this behaviour where although I knew I was on the ground, the GPS didn't.

 

I don't look at the phone at all in flight; at certain points I don't even look at the instruments, I'm concentrating on flying the plane straight and level 40 ft above the runway. but I'd like to know if I achieved this in the post mortem.

 

 

[Hildy]

Hildy,as has been said above- id ditch the compass...at least until you have finished your flight, then you can review it, but i wouldnt use it in flight.

The constant viewing of the runway is what will determine your circuit performance. The gps is going to add too much to your mind at this stage, and can be a hinderance.

 

With regard to how long before turning, etc in the circuit, this is the approach i use.....continue on upwind until 500ft has been reached.....turn onto crosswind, looking underneath my wing, ( i fly a Jab), until i can see the runway appear....level the wings...this concept usually gives a pretty good 90 degree line from the upwind point.

 

when i have reached 45 degrees from the end of the runway, is when ill turn downwind....roll the wings level, to track parallel to the runway....always looking at that runway throughout downwind to determine any drift you may encounter.......at 45 degrees from your threshold...turn onto base, again giving you a nice 90 degree line to the runway. the turn onto final is pretty simple, and you will pick up the turning points eventually, as the wind will always play games with you. Usually, in the Jab with an approach speed of 65-70knts, i aim to turn final at 650ft, which should allow for an established, wings level line on final, by 500ft.

 

i know its a bit long, but i hope it helps.

 

Liz.

This is perfect advice. my instructor picked a few landmarks that I was to aim for; this doesn't work on a foreign airfield, of course. but I don't know whether i'm turning from crosswind to downwind too early - it's quite hard to pick 45 degrees. I'm using the landmark picked out but as you can see, there's still quite a bit of inaccuracy with this method - there are tracks which are 600 feet away from each other!

 

Also, I have been flying a semicircular base, but I knew that in flight. I think it's because I don't have the knack of a coordinated descending turn yet.

 

 

[Guest davidh10]

... my instructor picked a few landmarks that I was to aim for; this doesn't work on a foreign airfield, of course...

Actually it does work for a foreign airfield, but you will pick the landmarks by observation relative to the runway. It could be anything, even a mark on the ground, a tree or an offset from something.

It will all come to you as you gain skills and experience.

 

Also, while looking at the tracks on the GPS later may be helpful, don't fixate on it. Landing isn't a formula. Apart from checks that must be performed, every landing is different. It's a seat of the pants thing. You have to compensate for conditions at the time. One day you will be a little high or low. Another you will have cross wind or differing wind direction at ground and circuit height, or gusts or down drafts, or thermals... Your instructor will show you the methods and tell you what to look for, but you have to apply each in the right amount at the right time, which won't ever be exactly the same.

 

 

[motzartmerv]

Howdy and welcome to the forum.

 

Some pretty good advice here. Did I read your first post correctly. You have 3 hours of flying, 2.5 of which is in the circuit?

 

 

[motzartmerv]

great minds...;)

 

 

[sfGnome]

I'm not a he

Oops! Sorry. How embarrasment...

 

 

[dunlopdangler]

Welcome to the forum Hildy. I guess by the comments so far you may have guessed that we are mostly bewildered that you would be doing circuits only after a couple of hours and being a little self analizing in flying such an accurate circuit so early in your flying...that will come with practice and you wont need a GPS or even your instruments to tell you that. By all means review your flight as you are doing with the GPS if you choose to carry it with you...but forget about it until well after...You are on a learning curve and at this stage all is in front of you as you have alot to learn. Don't have the GPS plotting to become a distraction for you to dwell on too much. Your primary task thus far is to learn to AVIATE-COMMUNICATE-NAVIGATE..the finese you can muck about with later...enjoy the journey and happy flying:plane:

 

 

[Hildy]

I thought it was aviate, navigate, communicate! I'm still on the aviating. Now got 2 hours of touch-and-goes down. Still trying to get the hang of how much stick pressure to use on flare.

 

 

[motzartmerv]

Hey Hildy. What aircraft are you training in, and where are you training?

 

 

[dunlopdangler]

It is Hildy...good to see you knew that.. I hope you got my point though....

 

 

[Hildy]

mozart: I'm learning in an LSA55.

 

I do understand your point, dunlopdangler; at no point during the flight am I thinking about the GPS. I am now using the downwind leg as a bit of a breather to stare out the window and remember why I am doing this; something like 50 circuits this week is starting to get me down a bit but I realise that I need to put in the hard yards now to be a better pilot later. I still have to look at the turn coordinator; my rear still doesn't know how much slip/skid there is. otherwise the actions on climbout/crosswind/early-mid downwind are becoming automatic; the main thing I forget in approach preparation is carby heat. I now have the hang of approach angle but I still need to develop the right feel on flare - at the start of every lesson I flare too much and bounce in the air a bit before touching down.

 

more circuits tomorrow!

 

 

[kgwilson]

I'm amazed. Circuits from flight No 1!! The tried and proven method when I did my PPL training was:-

 

1. Aircraft Familiarisation. Briefing 30 mins, Flight 30 mins

 

2. Effect of Controls. Briefing 30 mins, Flight 30 mins

 

3. Straight and level. Briefing 30 mins, Flight 30 mins

 

4. Climbing and Descending. Briefing 30 mins, Flight 60 mins

 

5. Medium turns. Briefing 30 mins, Flight 60 mins

 

6. Basic Stalls. Briefing 30 mins, Flight 60 mins

 

7. Power & Flap Stalls. Briefing 30 mins, Flight 60 mins

 

8. Circuit Introduction. Briefing 30 mins, Flight 60 mins

 

Then it was circuits till solo including with/without flaps, EFAT etc . All or any of the above would be repeated if the student had not been able to cope adequately in any lesson.

 

All of the first 7 skills are required to be mastered before beginning circuits in my opinion as they are all used in circuit flying. GPS's hadn't been invented then and even as a review item I really can't see much benefit due to windspeed, crosswind component (this would have to be minor crosswind) different base turn point with flaps or without etd. Some of these change on a single flight.

 

By having those first 7 skills under your belt all the things that happen in circuit flying can be far better managed. Circuits especially with other traffic can be very stressful to a new student so any way to reduce that stress level by the student feeling more comfortable with his/her skills is a bonus.

 

 

[Hildy]

I'm at a little aerodrome with almost no traffic. I'm pretty happy with 1-5 - I can do a coordinated 90 degree turn, climb, descend, etc. That was the first half hour of time, pretty much. Then it was circuit introduction with an overfly of the runway at about 100ft, two hours of getting that down to 20ft, an hour of trying to get it down to 5ft, and two hours of touch and go.

 

I would like some more time with stalls.

 

cficare: they're getting me down because I didn't progress anywhere near as fast as in the first hour. they're hard work! I have to spend every minute concentrating rather than staring out the windows thinking about how much fun flying is. but my last hour has been good - I'm nailing 50% of landings nicely and coming down a bit hard or bouncing the other 50%. I want that to be 90% by the end of tomorrow.

 

 

[motzartmerv]

So is it power-attitude-trim or attitude-power-trim when leveling off from the climb?

 

 

[Thirsty]

Hildy - of course learning in an LSA55 makes the whole process harder as well. I'm learning in one and it took a few hours before I felt comfortable. I still don't fly balanced all the time (I've done around 14 hours now) so it's not just you :)

 

You already know this probably but perservere - you'll get to the point where the penny will drop and it'll start falling into place. I reckon you've started ccts a little early as well but you're there now so it won't be long. None of us ever land well all the time either so I wouldn't worry too much about that aspect either - again teh LSA can be a bit of a handful in the flare 'cause the controls aren't all that effective at slow speeds.

 

I also know what you mean about hard work - I've been doing short field landings lately and at the end of 30 mins of that I feel really stressed. I asked my instructor to do one and he made it look soooo easy. Annoying as hell ;)

 

 

[Yenn]

I have long held the view that pilot training could be improved and my personal thought is that it would be better to do some cross country flying as well as circuits. Do a circuit at home base then fly somewhere else and do circuits there, or maybe practice emergency procedures or steep turns, gliding and climbing turns. My reasoning is that it prevents boredome and also contributes to making a better pilot. Of course your instructor may well be correct in his methods as I am not an instructor, but have seen a lot of people drop out of flying training due to boredom or fear that they will never succeed.

 

 

[Hildy]

You already know this probably but perservere - you'll get to the point where the penny will drop and it'll start falling into place. I reckon you've started ccts a little early as well but you're there now so it won't be long. None of us ever land well all the time either so I wouldn't worry too much about that aspect either - again teh LSA can be a bit of a handful in the flare 'cause the controls aren't all that effective at slow speeds. I also know what you mean about hard work - I've been doing short field landings lately and at the end of 30 mins of that I feel really stressed. I asked my instructor to do one and he made it look soooo easy. Annoying as hell ;)

The penny dropped today - my last few landings were better than the first few. I think it's because I've come from MSFS where the stick has no pressure, just a position, and the plane is nice and docile in gentle winds.

 

I've now flown the LSA55 enough to know that I don't want to buy one.

 

Mozart: attitude, power, trim - or that's how I do it. that's because I still want a decent amount of power to accelerate from best-climb speed to cruise speed, so there's no point in cutting the power too early.

 

but i'm a voracious reader and i read multiple online groundschool tutorials before my first TIF even.

 

yenn: I think that's true. my motivations may be different in that I have a limited amount of time at this school before I move again so I want the highest yield training, even if it's not as much fun. but two lessons in the morning and I'm completely knackered for the day. it's almost as tiring as spending 8 hours at work.

 

 

[fly_tornado]

but more fun than 8 hours work

 

 

[Hildy]

not for me! I love my work. I do want to do the CPL... but I wouldn't want to quit my day job, I love it that much.

 

 

[fly_tornado]

the eaa has a video series on learning to fly http://eaa.org/wings/

 

 

[Guest Dick Gower]

Best not to learn visual clues around the airport because they won't be there at any other airport.

 

Better to do everything by reference to the runway only. This will work anywhere.

 

The GPS may have some value to see how square your circuits were and how accurate you were rolling out on the centre line turning final but I would ignore any information in the vertical sense. At three hours you will only just be starting to develop the skills to recognise undershoot or overshoot and cope with the variables, such as wind gradient, that wont appear on the GPS.

 

 

[sfGnome]

the main thing I forget in approach preparation is carby heat.

I can still remember the day I finally remembered to add carby heat without being reminded. Why is that the hard one to remember??

Now you've got me intrigued. What possible job is there that could be better than flying? I've got a great job, but if flying paid the bills then work wouldn't see me for dust!

 

p.s. Back on your gps logging question, I should have mentioned that while gps is remarkably accurate in the horizontal plane, it is much less so in the vertical. Large absolute errors and variations over time are common in the elevation, so even if you wanted to review that aspect, it just isn't worth it. The only value I've found in looking at the elevation trace is to count the number of circuits I did...

 

 

[Hildy]

I was hoping that I could work out where my touchdown point was in relation to the runway, but if ground level is inaccurate that doesn't help.

 

I've never driven a car with a carburetor or a choke. I also turn the radio on and off in the wrong order. I need to make myself a new mnemonic for the checks.

 

 

[facthunter]

You can't make flying into a lot of numbers and predictions. Situational awareness will get you through. Better to understand why things are done than to invent some way of remembering to do them. A check is meant to be a follow-up. You do ACTIONS as part of managing the flight. The checklist should not prompt them, but merely confirm that they are done, for your peace of mind ( and safety). Nev

 

 

[motzartmerv]

I worry about students that don't get the full pre circuit instruction on basic sequences.

 

Sure you could take any student up for half an hour and show them "this does this, that does that" and then bash circuits. But without the grounding in basic skills I wonder what would happen in the long run.

 

For example, in the effects of controls sequence (normally 1 hour flying time) the instructor would have programmed into the student from the start that when the throttle comes right out to idle (or a low power setting), the carby heat also comes out to full ON. Its part of the reducing power sequence of actions that would, if the time had been spent on the first lesson, already be automatic.(Carby heat, power, adjust attitude, center the ball, speed, trim)

 

Trying to learn to fly as well as learning to fly a circuit is (in my opinion) like learning to drive on the autobarn.