rate-one turn in holding

[Pink Panther]

Hello,
A couple of weeks ago I learned on this board that fast planes do not use a turn coordinator because of the high speed. A standard rate turn needs an excessive bank.

How do big planes fly a holding, what bank do they use and how long does it take to complete a 180-turn in the holding pattern.

Thank you,

 

[Fly2Scuba]

30 degrees max bank for most airliners is allowed in normal operations. Here is a simple forumula to determine bank angle for standard rate turns...

Airspeed in knots divided by 10 and add half of that value.
Example:
IAS 100kts divided by 10 = 10 + 5 = 15 degree angle of bank

2. Standard rate turn bank angle varies with speed. The airspeed in MILES PER HOUR less the last zero and plus 5 will give about the required angle of bank on the attitude indicator.


So at 200 knots GS divided by 10 = 20 + 10 = 30 degrees of bank. Most turbojet airliners hold at a minimum of 200 knots indicated at least 10000 feet MSL well exceeding 200 knots GS.

 

[EagleRJ]

Airliners are still bound by the FARs concerning holding speed. The autopilot will make turns at 27 degrees angle of bank, and as long as you are below the maximum holding speeds (200/230/265), you will remain in protected airspace.
Airliners also have published holding speeds, which are intended to maximize endurance. Most pilots hold at a faster speed, though, because Vhold is uncomfortably slow.

It's true that a turn coordinator is not used due to the higher speeds. Large planes use 27 degrees of bank as standard rate when maneuvering in terminal areas. When enroute however, 15 degrees of bank is usually used, for passenger comfort as well as increased low-speed buffet margin. It gives you a much larger turn radius, but that's fine as long as you stay within the airway.

 

[Singlecoil]

Rate of turn is a function of True Airspeed, not groundspeed as stated above.

I found an excellent site with a thorough analysis of this topic. Their rule of thumb is TAS/10 + 7 to yield degrees of bank for a standard rate turn.
Here is the site.


The 27 degrees of bank must be a Saab thing as I have never heard of that before. The Dash-8 would do 25, and the MD-80 will do 10, 15, 20, 25, or 30 degrees of bank.

 

[avbug]

Angle of bank varies with the system in use. Average standard for an autopilot is 25 degrees maximum, with less being used for shorter turns.

Typically a flight director will show 20 degrees of bank variable for the amount of turn required, and the rate of turn required (closure on course, etc).

The rate of turn is then a function of angle of bank, and speed.

 

[SuperFLUF]

When using a Smiths FMC for holding, it plans 25 deg. turns but will go up to 30 deg. to stay in protected airspace, depending on the airspeed and wind conditions.
Once it has calculated the pattern (based on programmed speed and wind conditions on the inbound leg), it will fly whatever rate of turn is needed (up to 30 deg. max) to follow the track it has drawn. This usually results in the bank angle varying throughout the outbound and inbound turns.

The hardest part of holding with an FMC is remembering to report the entry.

Oh yeah, and whether or not to eat the leftover first class cookies, cuz they're usually ready about the time you start to hold.