Hi,I have a few questions. When doing some procedure turns, I find it hard to figure out which bank angle to use. I read in another topic that the rule of thumb for the 737 is: 15% of TAS (True Air Speed). So for example your TAS is 150 KTS. So your bank angle is 0.15 x 150 = 22.5 degrees. But of course your bank angle for the procedure turn does also depend on the turn radius specified on the chart, correct?So I have two questions: 1. The definition of the turn radius is half of the diameter of the turn, correct? So for example you're flying heading 360, then you're doing a 180 degree right turn to heading 180, with a turn radius of 1 NM. After you did the turn, you have moved 2 NM to the east, correct? Because the diameter of the turn is 2 NM (2 x turn radius). 2. How do you know the turn radius you should use. For example when circling to land on RW08 on LOWI? 3. How do you know which bank angle to use for a specific turn radius? The rule of thumb is 15% of TAS, but for which turn radius is that rule? 4. How do I know when to start the turn? I know you can tune an NDB or VOR, but still, at how many degrees from final approach course should it be pointing then for the start of the turn?I'm just very keen to learn about aviation, and there is just so much more to learn. Would be great if you guys can help me on this one! Thanks

Turning procedures are based on standard rate turns, which produce a 180 degree change in direction in one minute. Thus the radius of turn will vary according to airspeed. For the same reason the rule of thumb you mention works for different speeds. Aircraft usually have a turn indicator which has an index mark for standard rate to assist. Essentially the pilot doesn't need to work out the radius because they fly the turn rate.However you can easily calculate it. For a standard rate turn, the aircraft will have travelled half the circumference of the turning circle in one minute. You know how fast it is travelling (in TAS) so you can work out what that distance is. Divide this distance by Pi to calculate the turn radius.Hope this helpsKevin hall

Turning procedures are based on standard rate turns, which produce a 180 degree change in direction in one minute. Thus the radius of turn will vary according to airspeed. For the same reason the rule of thumb you mention works for different speeds.For a standard rate turn, the aircraft will have travelled half the circumference of the turning circle in one minute. You know how fast it is travelling (in TAS) so you can work out what that distance is. Divided this distance by Pi to calculate the turn radius.Hope this helpsKevin hall

Wait, you say that all procedure turns on charts would take 1 minute? Correct? So if the procedure is 90 degrees, it would still take one minute? So the bank angle will be twice as low, correct?

Wait, you say that all procedure turns on charts would take 1 minute? Correct? So if the procedure is 90 degrees, it would still take one minute? So the bank angle will be twice as low, correct?

No the bank angle should be such that it will produce a 180 deg/min turn rate. A 90 degree turn will be complete in 30 seconds.Kevin Hall

The way I have understood it the ROT (rate of turn) is 3 degrees a second. 1 minute = 60 seconds 180 degrees / 60 seconds = 3 degrees per second.

No the bank angle should be such that it will produce a 180 deg/min turn rate. A 90 degree turn will be complete in 30 seconds.Kevin Hall

But the bank angle will always be 15% of TAS, correct? So if I'm flying at 150 KT TAS, the bank angle will be 0.15 x 150 = 22.5 degrees, and in this way, a 180 degree turn would be complete in 1 minute, correct?

Bank angle is not important. The pilot increases or decreases the bank angle to ensure that they are turning at a rate of 3degrees a second. Mentally calculating the bank angle required as your speed, direction and headwind change during a turn is not possible in real time (nor is it necessary). Instead simply check your heading and your clock every few seconds. If you haven't turned as much as you wanted, increase bank, if you turned a little further then expected, reduce bank. This leaves the pilot with time and attention to track instruments, landmarks, traffic and so on.

But the bank angle will always be 15% of TAS, correct? So if I'm flying at 150 KT TAS, the bank angle will be 0.15 x 150 = 22.5 degrees, and in this way, a 180 degree turn would be complete in 1 minute, correct?

Yes, 22.5 degrees for 150 KTAS gets you very close to the actual value to achieve 180 deg/min. If my late night maths is correct it is actually 22.395 degrees. This applies to any aircraft in a coordinated turn by the way, not just the 737.The actual bank angle required doesn't quite increase linearly with speed though, so the rule of thumb is only approximate. For example at 250 KTAS, the rule of thumb gives 37.5 degrees bank, whereas 34.48 deg is actually needed.Kevin Hall

Yes, 22.5 degrees for 150 KTAS gets you very close to the actual value to achieve 180 deg/min. If my late night maths is correct it is actually 22.395 degrees. This applies to any aircraft in a coordinated turn by the way, not just the 737.The actual bank angle required doesn't quite increase linearly with speed though, so the rule of thumb is only approximate. For example at 250 KTAS, the rule of thumb gives 37.5 degrees bank, whereas 34.48 deg is actually needed.Kevin Hall

What is the rule or formula to get the bank angle?

Just tried the rule of thumb, and it didn't entirely work for me though. Go to this link:http://www.fly-sea.com/charts/EGKK.pdfNow refer to charts 21-1. There you see and ILS/DME RW08R, with a procedure turn. I was coming from the MAY VOR, heading 277, towards the MID VOR. As shown, I started a right turn exactly 5 NM from the MID VOR, to heading 080, to intercept the localizer of ILS 08R. I used approximately 20 degrees of bank, because my TAS was around 150. But in the end, I came out wayyy to early, around 0.5 NM to the right of the localizer. What am I doing wrong? I'm sure that my bank angle was really accurate and stable all the time, because I was using CWS, and A/T.

What is the rule or formula to get the bank angle?

If you read my original post, I said that the rule of thumb to get the bank angle for a procedure turn is 15% of your True Airspeed (TAS). You can see your TAS on the ND. So if you TAS is 150 KTS, you should use 0.15 x 150 = 22.5 degrees of bank.

What is the rule or formula to get the bank angle?

1. Calculate how far the aircraft will fly in one minutes = V * 1862 / 60 meters (where V is TAS in knots)2. Calculate the turn radius, r, which is distance travelled divided by Pi.r = s / π meters3. Turn rate, ω , is 3 deg/sec which is 0.05236 rad/sec4. Lateral acceleration = ω ² r m/sec² = 0.00274157 * r5. Bank angle = arctan (lateral acceleration/9.80665)(where 9.80665 is the acceleration due to gravity)Kevin Hall

Just tried the rule of thumb, and it didn't entirely work for me though.Go to this link:http://www.fly-sea.com/charts/EGKK.pdfNow refer to charts 21-1. There you see and ILS/DME RW08R, with a procedure turn. I was coming from the MAY VOR, heading 277, towards the MID VOR. As shown, I started a right turn exactly 5 NM from the MID VOR, to heading 080, to intercept the localizer of ILS 08R. I used approximately 20 degrees of bank, because my TAS was around 150. But in the end, I came out wayyy to early, around 0.5 NM to the right of the localizer. What am I doing wrong? I'm sure that my bank angle was really accurate and stable all the time, because I was using CWS, and A/T.

You aren't doing anything wrong. Before you start the turn, you would have the ILS tuned already and LOC armed on the MCP. As you turn towards the runway heading you should capture the localiser and line up rather than follow an exact turn rate ignoring the localiser. Basically, not all the turns on an approach chart are standard rate turns. Those in holding patterns are, as are those in procedure turns (which is where you reverse course by turning 45 degrees away from the localiser, fly for 1 minute, turn 180 degrees back towards the localiser then intercept it). If you are in any doubt perhaps you should ask one of the RW pilots on this forum, I don't want to mislead you.Kevin Hall

Folks,I use TAS/10 + 7 with the bank angle limited to 25 degrees (30 degrees max). Bill

Bill is correct. Rate 1 (Standard Rate) or 25 degrees angle of bank, whichever is less. Trying to mentally calculate it in your head when flying and approach etc. is asking for trouble - keep it simple - use the instrument that tells you what rate you are turning.

Just tried the rule of thumb, and it didn't entirely work for me though.Go to this link:http://www.fly-sea.com/charts/EGKK.pdfNow refer to charts 21-1. There you see and ILS/DME RW08R, with a procedure turn. I was coming from the MAY VOR, heading 277, towards the MID VOR. As shown, I started a right turn exactly 5 NM from the MID VOR, to heading 080, to intercept the localizer of ILS 08R. I used approximately 20 degrees of bank, because my TAS was around 150. But in the end, I came out wayyy to early, around 0.5 NM to the right of the localizer. What am I doing wrong? I'm sure that my bank angle was really accurate and stable all the time, because I was using CWS, and A/T.If you read my original post, I said that the rule of thumb to get the bank angle for a procedure turn is 15% of your True Airspeed (TAS). You can see your TAS on the ND. So if you TAS is 150 KTS, you should use 0.15 x 150 = 22.5 degrees of bank.

I don't normally use Jepp charts, but there does not appear to be a procedure turn displayed in the approach plate that you reference. That is what I call a Procedure Track (PT), a course that is to be followed. The trun will not necessarily be a standard rate turn back to the LOC because of airspeed or wind direction/speed. The easiest way to intercept the LOC would be to start the turn with a 20 degree bank (approxomately) and see what the the Trend Vector is showing on the ND and adjust the bank angle to where the Trend Vector is intercepting the LOC where you wish. Back in my steam gauge days I would have had the ADF set and adjusted our rate of turn based on the ADF needle. The Trend Vector makes life much easier. The bank angle will vary based on KIAS and the wind direction and velocity. Unfortunately it is a "feel thing" based on experience. I still use raw data to verify the ND/PFD. The old trust but verify thingy. <G>Bill