B737 Visual Circuit Tips & Techniques

[2XL]

Anyone prepared to share the secret to their successful visual circuits in the B737. All tips and techniques appreciated.

[LEM]

If I told you, it wouldn't be a secret anymore!

[duece19]

Pretend its a cessna and fly the approach for what it is, a visual manouver. Some people tries to turn it into a very complicated procedure, and it all goes into to a bowl of s**t.

Just look out the window and fly as you always done. works fine for me :)

Cheers

duece

[Centaurus]

Presumably you are doing the circuits in a simulator? Some pilots like to hang on to the automatics in the circuit which is a waste of valuable time and sometimes indicates lack of confidence in one's basic flying skills. Others use partial automatics like leaving the FD's and autothrottle engaged. Still others fly the circuit in MAP mode with partial automatics without looking outside very much.

Or you can bite the bullet and enjoy the pleasure of flying circuits without the bells and whistles of automatics and MAP modes.
It all depends on your personal viewpoint. Circuits are excellent for increasing your scan rate, while the primary objective of touch and go landings is approach and landing practice. They are not intended for landing roll and takeoff procedure training (see FCTM relevant paragraphs).

Here is one suggested method of practicing 737 circuits in the simulator. Personal viewpoint of the writer only, so please no brickbats from the experts!

Switch off the FD and autothrottles for take off and launch. Use flap 5 for convenience. Aim for climb speed 180 knots and leave flap at 5. At 1000 agl start turn at 30 degrees angle of bank - maintaining bank angle until arriving at downwind hdg and hauling back throttles to maintain 180 knots while levelling at 1500 ft agl. Set Vref for landing flap from previously set V1 and VR.

Up to you whether you set MCP cursor at 180 knots or set Vref+5 now. You are not using autothrottle so the MCP speed is purely a reminder figure rather than an A/T setting. Ensure A/T is switched off and not just ARM (see FCTM cautionary paragraphs on autothrottle use in ARM mode - Boeing do not recommend it)

Downwind keep eyes on runway and visual tracking. Don't stare at MAP. Abeam landing threshold hit stopwatch, select gear down, flap 15, arm the speed brake if full stop landing and allow speed to reduce toward 150 knots and call for landing checklist to flaps.

45 seconds after passing end of runway, turn base 25-30 degrees angle of bank and square off the circuit because of slower speed of 150 knots. Avoid flying a 5 degree bank angle turn as this is sloppy flying. If an ILS is available ensure the standby ADI ILS is selected because it gives you earlier glide slope indication than primary ADI/HSI glide slope. Very useful if the simulator is limited in side view.

Flap as required on base and final. Cross the fence at Vref if no wind and use reverse and manual braking. This gives you the practice at modulating the brakes as a skill rather than always carrying out autobrake use which can lead to loss of braking technique skills.

For touch and go don't arm the speed brake and no reverse. On touch-down open up to 50-60% spool-up N1, select flap 15 at same time set stab trim at 5 units. When ready, set take off thrust and rotate at Vref which had already been set. Around 1000 ft agl select flap 5 and aim for 180 knots and repeat the circuit. Note at no stage was FD, AP or AT used. Miminum talk in the cockpit.

For asymmetric circuit practice simply maintain flap 5 downwind and 180 knots, pull back one throttle to idle early downwind, set flap 15 Vref in ASI and you are on your way again.

Hope this is some value. But forget use of any automatics if you want real value in circuits -just stick to manual flying raw data no AT. You will really enjoy the experience.

[BOAC]

2xl - if you are asking about simulator circuits, that is a good answer. If it is 'for real' circuits, there is NO answer! Each 'arrival' at an airfield is different, depending on where you see it and from which direction/ energy level you arrive. I always try to 'build' my flight path back from the 'stable' point, be it 1000', 500', 300´or whatever, to the turn in point, to where I need to start slowing (from the 300kts downwind join :D). These circuits need a flexible approach to flying them and cannot be 'taught´since each one is different.

[Global Pilot]

Centaurus, great post and will try your technique next time in the sim but like to start the inital turn at 700 feet to keep the circuit a bit tighter.

Another tip is to keep an eye on the airfield by setting it up on map mode with an extended centerline.

Not sure which of these you are after but here goes:

1.Circling Approach-
Config at MDA(H): Gear down,flap15,speedbrake armed, verify alt hold, set missed approach alt, HDG SELECT offset 45degrees track, timing 20 secs from wings level.
Abeam threshold:Timing-3 seconds per 100ft AGL. Wind correction 1/2 TWC or HWC(kts) in seconds.
Turning base leg: Set Rwy heading, landing flaps, call for landing checklist.
Intercept the normal visual glide path and disconnect A/P and A/T, recycle FD's
Follow the PAPIs in.

2.Visual Traffic Pattern-
10nm from touchdown set flaps 1
Entering downwind set flaps 5
Abeam threshold set missed approach altitude and recycle FD's
Before base turn, Gear down, flap15, landing checklist to flaps
Turning base, Flaps25 and start descent if needed
Base, landing flaps and complete lading checklist
500ft be stabilized on profile.

3.Circuit training-
Upwind, Gear up, 400agl with white bug increasing Flap5 and turn downwind
Downwind, complete after take off checks and descent and approach checks
Abeam threshold, timing(T) 30secs +/- 1/2 total wind correction
Before turning base, T+30, gear down, flap15, landing checklist to flaps
T+45, flaps25, turn base, descend at 500fpm
Approaching profile, landing flaps, landing checklist but do not arm speedbrake or autobrakes for touch and go
Main wheel touchdown, Advance throust levers to approx 60-70% N1
After nosewheel touchdown, flap15, trim to approx 5.5units
PNF call "Go", advance to approx 90% N1, call "Set takeoff thrust"
And around you go again!!

[QNH1013]

All great advice.
Centaurus's tip about having an ILS tuned (if available) is a good one. There is nothing wrong with using the aids that you have as a backup or guide. Personally I find it usefull for when turning base and seeing vertical profile on the glideslope as you will be starting your decent but may not have runway in sight yet, especially if it's the SIM. Having MAP mode to see when you are abeam the downwind threshold to start timing is also useful. At night, reality is, with all the lights around, you just can't see it sometimes.

[2XL]

Sim info is good however prbably more interested in flying the line. Cheers

[HSWL]

2XL. In that case see BOAC reply. On the line forget about the raw data stuff. Keep the captain happy by flying the automatics until you can see the runway right in front of you then check with him if he approves of you disconnecting the autopilot on very short final. Some get very twitchy and apprehensive if you try manual flying.

[Zenj]

Centaurus,

Let me know more on Boeing not recommending A/T as per your below remarks. thanks

Zenj


===================
Ensure A/T is switched off and not just ARM (see FCTM cautionary paragraphs on autothrottle use in ARM mode - Boeing do not recommend it)
===================

[LEM]

On the line forget about the raw data stuff. Keep the captain happy by flying the automatics until you can see the runway right in front of you then check with him if he approves of you disconnecting the autopilot on very short final. Some get very twitchy and apprehensive if you try manual flying.
HSWL, I get mad when I see FO flying a visual on automatics!!!!!!!!!!!!
Totally slaves of autopilot!
A visual is to be flown raw data, to practice, to feel a pilot, not just an operator, and to enjoy it!!!


Zenj, abari?
Centaurus correctly quoted the training manual, page 1.34:
"The autothrottle ARM mode is normally not recommended because its function can be confusing."
I used to use it, to have minimum speed protection and go around thrust setting automatically if needed, but it's true that if you let the speed decay a bit tto mauch on final, the ARM mode will egage in SPEED, and then it can be a bit annoying to cancel it...
Qwaheri! LEM

[Blip]

Has anyone ever sat down and drawn a scale diagram of a visual circuit? You would be surprised just what a profound difference the following has on a circuit.

True Air Speed.

TAS squared determines radius of turn. TAS increases with an increase in temperature and altitude.

150 kts IAS during a 1500 ft AGL circuit in Sydney in ISA gives a TAS of 154 kts. Radius of turn using 25 deg AoB is therefore 0.74 nm
A similar circuit with 150 kts IAS in Ayres Rock at 35C (ISA+26) gives a TAS of 165 kts and a radius of turn of 0.85 nm. Thats adds an extra 0.3 nm to your track miles during a 180 degree turn.

Wind.

It too has a profound effect on the circuit.

The downwind spacing from the runway especially when the wind is blowing you towards the runway and is up your tail on base leg needs to be sufficient to allow you to turn the heading more than 180 degrees (180 degrees plus 2 x drift) and not go through the runway centreline on final.

Downwind timing from abeam the runway threshold to turning base is also affected (assuming you want to keep the final approach length consistant).

Most circuits you do in the simulator are ones where you're turning onto finals at around 800 ft AGL at about 2.5 nm. But consider when else you might be required to make a visual manoeuvre to landing. A circling approach! There are still plenty of them out there. Ayres Rock RWY 13 is one that comes to mind.

The B737 is a catagory C aircraft so the Circling minima is often 4000m visibility. 4000m equals 2.1 nm. Have a think about how you are going to keep a B737 within 2.1 nm of the threshold. That's not a 2.1 nm final either. You need to keep the base turn within this distance if you are going to maintain visual contact with the runway. Draw a circle with a radius of 2.1 nm centred on the runway threshold and see what it takes to keep an aircraft with a TAS of say 140 kts and 25 deg AoB within the circle!

Clue: Turn Radius (nm) = TAS^2/(68,412 x tan
AoB).

Never mind when the TAS is 165 kts as in the example above!!

The point I want to make here is that the tracking distance to the runway can vary considerably. Therefore the altitude gates that you want to pass through along the constant 3 degree descent path to the runway (abeam the runway, starting descent from the circling minima, turning base, turning final) will vary considerably too.

Have you ever been turning base and not quite sure how it's going? (Am I high? Am I low?) I have. But ever since I sat down and nutted out all the various Circuits that I am likely to need ie:

a) 2 Engine fine weather circuit
b) 2 Engine low visibility (4000m) circuit
c) Engine out (FLAP 15) (TAS 170 kts) circuit

and noted down what effect winds of 10 kts, 20 kts, 30 kts from various directions can have on them, I've been able to fly my circuits with confidence and consistancy.

I hope this helps. :)

PS I can email you a copy if you like.