Rwy20 wrote:
It is 1.5 minute legs at or above FL140 according to ICAO PANS-OPS. And 25 degrees is not going to cut it for a standard rate turn at that speed. An approximate formula to calculate bank required for a rate one turn is: TAS/10 + 7.So at 265 kts you’d have to bank at approximately 33.5 degrees.
1.5 minute legs but it doesn’t mention how long do you have to fly tear drop leg. 33.5 degrees are not allowed to commercial airliners…
It’s the lesser of rate 1 or 25 degrees bank.
Teardrop is like flying the ‘gate’ in UK parlance, and you would adjust both timing and the outbound track for wind. What wind vector did you assume? You would position to roll onto the inbound track to achieve 1 minute 30 seconds above FL140.
wind is zero
I have asked an Airbus pilot, and he said the 25 degree limit is for passenger comfort and it’s not active when you fly in heading mode – at least at lower altitudes. But if you are told that you will get an enroute hold, the first thing you do is already to reduce to minimum speed; that is one thing where this scenario isn’t realistic. Also, if you are getting a radar service, which would be everywhere in Europe at this altitude, you would ask for longer legs like 4 minutes for your hold to avoid having to turn all the time. And the last remark I have is that the maximum speed limit etc. are for the assurance of the protected area of the hold, but that doesn’t necessarily mean you can fly your hold entry without overshooting the turn onto the inbound track.
4 minutes probably will solve this.
Otherwise what is the bank limit for the autopilot in Airbus? 30? For 737 30 is the maximum bank angle you can set. Anyway autopilot is not going to bank like 60 degrees if you enter opposite heading this is for sure. Holding radius is dependent on TAS so at altitude it will be difficult to turn even at minimum speed.
Rwy20 wrote:
the maximum speed limit etc. are for the assurance of the protected area of the hold, but that doesn’t necessarily mean you can fly your hold entry without overshooting the turn onto the inbound track.
IIRC unless specified otherwise, standard entries into the hold are also protected but only if the entry maneuver uses standard rate turns (otherwise, it is not standard).
AP max bank angle in Airbus aircraft is complicated and depends on the situation. In order to intercept a leg (i.e. the leg is planned in the FMS), an A320 AP will bank as far as 30° if necessary. If you are just turning the HDG knob it would bank up to a value between 15° and 25° depending on speed. The pilot can not set max AP bank angle in an A320.
AlexG wrote:
IIRC unless specified otherwise, standard entries into the hold are also protected but only if the entry maneuver uses standard rate turns (otherwise, it is not standard).
Are you sure it is not protected at 25° bank if the TAS is above about 180 knots? I guess the answer is in PANS-OPS, but I don’t have time to dig into it right now.
I am no expert at all but my Avidyne boxes depict the size of the pattern depending on the speed so I would know exactly how far my outbound leg should be. I can’t imagine a Boeing FMS system not doing the same.
Airborne_Again wrote:
Are you sure it is not protected at 25° bank if the TAS is above about 180 knots? I guess the answer is in PANS-OPS, but I don’t have time to dig into it right now.
PANS-OPS states that turn in a hold should not be made with bank greater than 25°. That means that offset entries with 25° bank that overshoot the inbound track are still protected.
Airborne_Again wrote:
Are you sure it is not protected at 25° bank if the TAS is above about 180 knots?
My bad, you are quite right. I see in my doc that the protection bank angles for holds are 25° for conventional or non RNP RNAV holds, 23° for RNP below FL245 and 15° above FL245. Of course, only valid if using those bank angles at max protected speed does not result in more than the standard turn rate.
