When to start turning from base leg to final?

[Haseen]

I am an aircraft maintenance engineer(Avionics) and as a hobbiest I am a serious flight simmer. I would like to know exactly when I should start the turn from base leg to final so that I can line up comfortably?

[fujii]

Too may unknowns in the question. Crosswind, headwind, tailwind, speed, bank angle.

[Haseen]

No wind condition. I am thinking of basic airplanes such as Cessna 172SP(in FSX), flaps 10, 80 Kts, bank angle 20 degrees.

[Jan Olieslagers]

When the threshold where you aim to touch down is at 135 degrees behind you.

[DeltaV]

Jan, base to final, not downwind to base.

[Jan Olieslagers]

oops!? my bad!
That must be a typical flightsimmers question - I've always been poor at guessing and estimating positions and distances, but never had trouble with turning into final.

[BackPacker]

Whatever is required to fit in with other circuit traffic. Might be over the threshold or even a bit down the runway, most common is about half to a full mile final, might be more if required.

Sometimes it's no problem to overshoot the centerline a bit, or even desired. Sometimes it's a big no-no because of other traffic flying an opposite circuit to the same or a parallel runway.

What's probably also important to consider is the altitude you're at when turning final. On a one-mile final, being at 700 feet is slightly high but still perfectly doable. Fly a threshold base at 700 feet and you can generally start planning on a go-around.

[AdamFrisch]

It depends on your rate of turn or turning speed and/or altitude. It's one of those visual images you have to re-learn with every new aircraft. But In my aircraft (about 100-115kts on base), it's about when I can see the field between 11 and 10 o'clock. Sometimes, when I'm a little high, I keep the speed up and turn tighter to lose some altitude.

[Heston]

You can't see the runway on the screen of a flite sim when you are on base - hence the question I guess. So there is no answer based on real aircraft practice that will work. Sorry.

H

[darkroomsource]

Best advice I ever heard for landing, and I've used it quite successfully in flight simulation as well....

pick a spot on the ground about 1/2 mile away (880 yards, ~800 meters), you want to be 400 feet (122 meters) above the runway elevation over that spot, pointing at the end of the runway to begin your final approach. That will give you an almost perfect glide slope, and sufficient time to stabilize your approach. (in practice, since it's hard to estimate distances without a reference, many small airports have a runway that's 800 meters, so you just use that length off the end of the runway, if your airports runway is 1600 meters, use half the distance, etc.)

Once you've picked that spot, you continue downwind until you've just passed that spot, then turn to base. You now have gone past the spot by about as much as you will get back when you turn to final. (look out the side window, when you pass it, turn)

Now, you just aim for that spot when you turn final, INSTEAD of looking at the runway. AND try to have your altitude be 400 feet (122 meters) above the runway elevation when you pass over it. Knowing when to turn to cross over the spot will take a bit of practice, especially in a simulator, because it varies depending on aircraft speed, turn rate (do not exceed 30 degrees in the pattern/circuit), wind direction and wind speed. But you can guess based on how long it took you to turn from downwind to base.

You are now set up for a final approach that should be stable. You have plenty of time to adjust your throttle (sink rate) and rudder/ailerons (runway alignment).

Next best bit of advice...
if you miss this spot, or miss the altitude by more than about 30 feet (10 meters), go around now, it's not worth trying to make it work for 2 reasons.
1) it's much easier if you have a stabilized approach starting 1/2 mile out (800 meters)
2) you are establishing two habits, first the approach habit, make it as clean as possible, and second the go-around habit, be prepared to go-around on every landing, and be prepared to go-around at the first sign of trouble

Later on, after you know what a good, solid, stabilized approach looks and feels like, you can try shortening or lengthening the approach.

[Whopity]

That is one of the fundamental deficiencies of a synthetic device, it does not replicate the aeroplane so you learn a technique that works for the device.

[darkroomsource]

Just to be clear,
the method I've described improved my landings immensely in real planes.
It works extremely well in flight simulators as well.

When flying larger planes, I have to change the distance and altitude (real and sim), for example in a C-152, 400' and 1/2 mile is almost too far away, in a Maule, it's definitely too far away, in a C-182 it's perfect, in a C-208 it's doable, but 1 mile and 800' is better, in a C-310 3/4 mile and 500' seems to be best.

Other heights and distances are workable, but that depends on experience in type and general experience.

[thing]

Is it just me that does it when it looks about right?

[dublinpilot]

The trouble with MSFS is that it's not easy to see the runway when on base, unless you have multi screens (or a super fast PC that you can quickly change the view).

In the real world you just keep an eye on the runway and start your turn when you think you'll have completed a 90 degree turn when exactly in line with the runway. In MSFS, it takes a lot of changing views to get that.

[mad_jock]

Knock the view off by 30degrees towards the runway and do a constant aspect approach.

[mad_jock]

I am going with "thing" look out the bloody window and don't bother with any fancy stuff.

[Steve6443]

pick a spot on the ground about 1/2 mile away (880 yards, ~800 meters), you want to be 400 feet (122 meters) above the runway elevation over that spot, pointing at the end of the runway to begin your final approach. That will give you an almost perfect glide slope, and sufficient time to stabilize your approach. (in practice, since it's hard to estimate distances without a reference, many small airports have a runway that's 800 meters, so you just use that length off the end of the runway, if your airports runway is 1600 meters, use half the distance, etc.)


"many small airfields have an 800m RUNWAY? Bloody luxury..... here in Germany we get 500m.... tops......."

Just joking, so back to reality - fortunately in Germany we have AIPs which have the circuit indicated clearly to ensure noise abatement is adhered to.... Just have to have your iPad / iPhone / Android running Air Nav Pro or similar, you can then easily see when you are expected to turn from downwind to base and base to final.......

[Shaggy Sheep Driver]

Crikey, it varies! At Manchester I've flown a base to final turn halfway down the runway (to land down by the fantail which dates the time I flew based aeroplanes from there).

At Barton, anything from half a mile out (only ever more than that if I was stuck behind someone flying a bomber circuit - not rare at Barton) to turning final over the fence (the Yak 52 liked that!).

At Liverpool in the Chipmunk I always kept the final very short so ATC had no problems fitting me in between the Airbusses etc (and I flew 120 knots clean to close-in base, then power off and slow down to VFE speeds lowering flap as those speeds were reached and turning final, then establishing fully stabilised at 60 knots on a short final).

There are other circumstances where different length finals apply.

[Gertrude the Wombat]

Is it just me that does it when it looks about right?
No, I'm sure what most people do.

And you're allowed to screw it up the first time, it's the second circuit, when you've already seen what the wind is doing once, that you're supposed to get it right.

[phiggsbroadband]

Hi Haseen, if your joystick has a 'hat' control it can be configured to give a look out of the side windows. If you just have the front view then you need to keep the end of the runway in the side of the view. The circuit needs to be flown at 1000ft. decreasing to 600ft at the base/final turn (at say 1/2 mile out.) Do you watch the PAPIs on Final? They are at the 3deg glide-slope.

Pete

[BackPacker]

The circuit needs to be flown at 1000ft.

No, you need to look at the "AIP" (Aeronautical Information Publication) or the "A/FD" (Airfield/Facility Directory - a US thing) for the circuit height for the airfield involved. It can be anywhere between 700' and 1500'. And that's above aerodrome level (AAL) - it may be something completely different on the QNH ("altimeter setting" in MSFS).

decreasing to 600ft at the base/final turn (at say 1/2 mile out.) Do you watch the PAPIs on Final? They are at the 3deg glide-slope.

A three degree slope (the normal PAPI/ILS slope) is 2000 feet in 6 nm (6.2 to be precise). So at 1/2 nm out you should be at about 160 feet, and not at 600 feet.

In a light aircraft you can descend a lot steeper than the standard three degrees slope though, so 250-300 feet at 1/2 nm out is still doable, although you will have four whites on the PAPI at that stage.

600 feet at 1/2 nm? I'm pretty sure someone will come out of the woodwork claiming that they can do it with full flaps and full sideslip but if you're landing on a short runway it is probably prudent to start the go-around.

Heck, if you unintentionally end up in that position, you've probably done so much wrong already leading up to that moment that it's best to fly away from the circuit, orbit in a quiet spot for a while to gather your wits and think about what you've done, and then try again. (Or hit the P button in MSFS.)

[thing]

And you're allowed to screw it up the first time, it's the second circuit, when you've already seen what the wind is doing once, that you're supposed to get it right

I would assume that the better pilot would know what the wind was doing the first time around..:).

[ianwild]

For VFR flying in MSFS, you need Track-IR imo - No point trying without!

I'm a brand new PPL and I've not landed at many places, but in no wind I was taught to turn when the furthest corner of the runway lines up with the nearest corner. With wind you turn a little before this point or a little after, depending on direction.

It works where I've flown, and it works in MSFS (With your Track-IR!). I guess as I step out I may well need to get a more sophisticated method and there's some very useful info in this thread. Thanks guys.

Ian

[Pace]

Think it was the military who flew curved approaches from downwind curving right onto final!
The idea of any approach and a circuit is an approach is to get you onto the runway to land not 1 mile out 2 miles out 3 miles out etc. Theoretically it could be just before you touchdown!
Wherever you hit the centreline is the point that coincides with the correct altitude for roughly a 3 degree glide.
6 miles 2000 feet 3 miles 1000 feet 1.5 miles 500 feet etc is a rough guide that is easy to remember and calculate.
In many ways it is probably better to visually extend the centreline and pick a prominent spot on the centre line like a farm or whatever and use that as a visual final approach fix. That is what you will fly over at a given altitude depending on an estimated distance from the runway.
Be 90 degrees to that point and passing 90 degrees start a curving approach.
may not be an official way but it works

Pace

[thing]

Think it was the military who flew curved approaches from downwind curving right onto final!

Still do, we do oval ccts at Waddo.

[Pilot.Lyons]

Im with thing on this one..... Jeese i got a real issue with this sort of thing.

Fly it!

[DeltaV]

I'm a fan of the curved approach too but even when that's not appropriate I like Base to be about in line with the end of the runway, certainly not outside the perimeter fence.