FAA ONLY!
Response from developer
The current version of the Holding Pattern APP for both ICAO and FAA methods of flying the holding pattern is identical when using the Along-Track-Distance (ATD) rather than time. The Holding Pattern APP solves for the exact RNAV Turn Point, which is a function of TAS, turn rate, wind speed, wind direction, and ATD. DME Turn Points are replaced by RNAV Turn Points. This allows all aircraft flying different indicated airspeeds and altitudes in the holding pattern to intercept the holding radial at the same ATD. The difference between ICAO and FAA holding patterns relate to the time issue. FAA specifies required inbound time, while ICAO specifies required outbound time. The only limit on the FAA method in order to intercept the holding radial at the correct inbound time while using a constant bank angle is the ratio of the windspeed to the TAS (i.e., the windspeed ratio) normal to the holding radial must be less than 1. In the ICAO method of specifying the outbound time, there is a significantly lower limit on the windspeed ratio normal to the holding radial. This limit is a function of the turn rate and the required outbound time. For example, in the case of a standard rate turn and a one-minute outbound leg, the maximum windspeed ratio normal to the holding radial is 1/3. Any value greater than 1/3 will not allow the aircraft to re-intercept the holding radial with a constant bank angle. Most avionics boxes use a variable bank angle to try to intercept the holding radial. This will work when the wind is coming from the non-holding side. In this case, shallowing the bank angle will allow the aircraft to re-intercept the holding radial. However, if the wind is coming from the holding side and the aircraft is bank limited, the aircraft will always overshoot the holding radial. Thus, it is impossible to intercept the holding radial under these conditions. Again, this does not occur in the FAA method since there is always a unique solution to the RNAV Turn Point Problem. We call this solution HPS (Holding Pattern Solution). The first paper on HPS was published in 2018. The Holding Pattern APP uses the HPS analysis. There are other benefits of using the FAA method for flying the holding pattern, one of which is called High Precision Entry (HPE). In HPS, the aircraft is assumed to enter the hold along the holding radial. In HPE, an additional parameter is incorporated in the analysis, which is the heading of the aircraft tracking inbound to the holding fix. Here the solution of the RNAV Turn Point allows the aircraft to smoothly blend into the HPS ground track, and thus allows the aircraft to re-intercept the holding radial satisfying either the required inbound time or ATD. This capability will be incorporated in the next update of the Holding Pattern APP. The methodology used in the Holding Pattern APP can significantly reduce the holding pattern protected airspace, as well as reducing Pilot workload in the cockpit for both entering and flying the hold. A dialog has been opened with the FAA to convince ICAO of the benefits of switching over to the HPS/HPE methodology. If ICAO converts to the HPS/HPE method of flying the holding pattern, they can still use their current maximum IAS holding speeds versus altitude tables, since HPS/HPE only requires the TAS, turn rate, windspeed, wind direction, and either inbound time or ATD.
Starting IFR now.
Best holding app hands down!
Response from developer
Glad you liked the holding pattern computer. In the next few days we will be releasing version 2.1 of the computer. The added features are: (1) EFC time capability. The Pilot inputs the EFC time and the computer will calculate a final holding pattern track that will bring the aircraft over the holding fix at the EFC time. (2) Heading indicator will rotate at the aircraft rate of turn, with a digital readout of the aircraft heading. (3) Wind direction barb on the heading indicator (4) Answer page now can show information on the aircraft ground speed and along track angle for the straight legs, and time for each of the turning segments. Also time to go in each of the legs, as well as time to the fix and time remaining to EFC. There are a few other features in this version that may interest you. Would greatly appreciate any feedback after using the new version. Best regards Les Glatt
Finally. A solution that’s not dumbed down to the point of being unusable.
I got more than my money’s worth from the app before I tried it in the airplane, or even in a sim. My understanding of wind effects on hold patterns has improved exponentially.
Response from developer
Glad to see that the APP helped improve your understanding of how the winds affect the timing and wind correction in the holding pattern. I just wanted to give you a heads-up on a new update coming out in the next few weeks. The new features are listed below: (1) In regard to the Expect Further Clearance time to leave the holding fix- You will be able to input the EFC time and the APP will provide a final outbound heading and time to allow the aircraft to reach the holding fix exactly at the EFC time. (2) The heading indicator will now rotate with the turn rate of the aircraft. You will see the aircraft move around the holding pattern ground track in real time, just like in the aircraft. (3) Wind direction and magnitude will be shown on the heading indicator and will rotate with the heading indicator. This will allow the Pilot to always maintain situational awareness about where the wind is coming from. In addition, a heading line will protrude from the aircraft so that you can see the wind correction angle during the holding circuit. (4) The answer page will also show timing for each of the legs, and along the straight legs, it will show the groundspeed and ground track angle the aircraft is flying. It will also show the radial and distance from the holding fix of each of the 3 points around the holding pattern. I also want to give you a heads-up on another release that will be coming in the next 3-4 months. This is a new and innovative procedure for entering the holding pattern. The method will still use the direct, teardrop and parallel methods for entering the holds, however, after crossing the fix, it will provide a heading and time to fly that heading, such that the aircraft will smoothly intercept the holding pattern solution. This will allow the aircraft to intercept the holding radial exactly at the require time or distance from the holding fix on the first entry to the hold. This method minimizes the footprint of required holding pattern protected airspace. If you would like to see an example of the holding pattern entry capability, send an email to lgtech@roadrunnner.com, and I will send you a few PowerPoint slides showing the capability. Best regards, Les Glatt
Pretty good
I would really like the heading indicator to point up. As you would see it in the airplane. This app only has north up and I have to turn my device to point it the right way. Please add this feature.
Brilliant
Great holding app
Wind adjustments to Hold patterns is a big plus !
Brilliant app!!
WIND 150/15KTS 89* + 23 = 112* (app computes 105*)
I had a response from Les providing a full explanation and used the app while trying a hold and worked perfectly will fully recommended to anyone! Thanks Les!
Response from developer
Sorry for the delay in getting back to you, but the Apple reply was down for about 5 days. The answer to your questions are given below. (1) Inbound WCA (IWCA) is given by Sin(IWCA)=(Vwind/VTAS)*Sin(alpha), where alpha is the wind angle relative to the inbound course. Since your inbound course 269 degrees, and the wind is coming from 150 degrees, the value of alpha is 119 degrees on the non-holding side (standard turns). The value of the windspeed ratio is 15/120=0.125. Thus, the value of the IWCA is 6.28 degrees, which is rounded off to 6 deg in the App. Thus, the inbound course would be 263 degrees. Note that in this case the wind is providing a tail wind component. The App shows a negative value, i.e. -6 since the IWCA is pointing toward the non-holding side. (2) You indicate that you are confused why you are not getting a factor of 3 between the IWCA and the outbound WCA (OWCA). The reason you are not getting 3 is the factor of 3 is a good approximation in two limits. The first being the weak wind case (windspeed ratio less than 0.05), and the second being when the relative wind angle is between 70 and 95 degrees from the inbound course. In this case, the wind is 119 degrees from the inbound course. The value the App computes the OWCA as -16 degrees (again, rounded off to the nearest degree). Therefore, the outbound heading would be 105 degrees.It should be pointed out that the ratio of the OWCA/IWCA on a tailwind component will always be bounded between the value 1 and 3. Wheareas, with a headwind component, the value of the ratio of the OWCA/IWCA is bounded between 3 and (3-wsr)/(1-3*wsr), where wsr=Vwind/VTAS. When the wsr gets close to 1/3, the ratio of the OWCA/IWCA can get large. For example when the wsr=0.3 with a headwind component, the ratio of the OWCA/IWCA is bounded between 3 and 27. This debunks nearly all the information on timing and wind correction in the holding pattern for the last 50-60 years. The details are in the technical paper. The user guide also shows a few examples of using the factor of 3 as the initial guess for the first circuit and compares it with the exact solution of the holding pattern. If you need any additional information, send me an email at lgtech@roadrunner.com Regards Les Glatt
Not just for hold entry
Great work with this app!
I am an airline cargo pilot flying without auto pilot and modern GPS, so your app has really eased the burden of figuring out hold entry and wind correction angle.
Mr IFR
Response from developer
I am responding to your comment regarding version 1.1 of the holding pattern computer. Version 2.0, uses an exact solution to the "Generalized Holding Pattern Problem". The outbound heading and time that is displayed on the APP, account for the drift in both the straight outbound leg and the two turning legs, in order to allow you to roll out on the centerline of the inbound course with the required inbound time or distance to the fix. The ratio of the outbound WCA to the inbound WCA, which you indicate should be 3, is not correct. The exact analytic solution shows that the ratio is 3 in the weak wind limit, which is valid when the wind speed ratio (windspeed/TAS) is less than 0.1. If your download version 2.0 and input wind speed ratios around 0.05, you will see the ratio is close to 3. Hope this answer helps you better understand the results you get using the holding pattern computer. Les Glatt
Best holding pattern app
Mr
Simply remarkable
Incredible and Easy to Use
I've looked at a dozen other similar apps, even purchased a few, but this one is by far "THE" best. In fact, there at no others that spell out exactly the heading and time you must fly after crossing the fix.
I use my iPad in the cockpit to receive ADSB data, and knowing this app is a click away is a tremendous comfort.
I hope over time, and with the use of this app, to be able to better visualize the hold entry and course to fly, but for now, I don't see ever being without it, even as just a safety check.
It's so easy and intuitive to use, I'm really grateful that someone thought up this app.
Thanks Mr. Developer!
Top
You never know it all
Wx decoder is a breeze.
Well done to the developer who must have a lot of aviation smarts.
Neil K
