PearlPilot

I am taking my commercial written next week and I have basically hit a wall on the chapter dealing with ADF and HSI. I have been pondering over the answers and explanations on the Gleim but it makes little to no sense as I have used the ADF perhaps once in my PPL days, and my HSI experience is limited to x-plane only.

I understand the MH+RB = MB questions, however questions such as the following are very confusing.

1. MH = 35.
RB =310.

To intercept a magnetic bearing of 240 FROM at a 30 degree angle (while outbound) the airplane should be turned?

2. If the airplane continues to fly on the heading as shown, what magnetic bearing FROM the station would be interception at a 35 degree angle outbound?

Although I don't use an ADF and HSI, it would be great to understand how to come up with the solution. I am not at all a proponent of memorization. It just doesn't make any sense to me. Any help to shed light upon this subject is greatly appreciated.

TheReelDeel33

This one will be hard to explain without being able to draw pictures and only having text to work with, but I'll give it a shot

Question 1)

First step, the reason the relative bearing is important for this question is so you can determine which way to turn. The RB shows the station to be out to the NW, and you are currently on a NE heading, so you will be making a left turn.

Now to figure out how many degrees you should turn to parallel 240 (the radial you are trying to intercept)

Turning left 155 degrees would put you on a course of 240 (I do the math quick by using N as a reference point, turn left 35 deg gets me to 360, and 360-240 is 120. So 120+35= 155) So turning left 155 degrees would parallel the radial. If you wanted to intercept it on a 30 degree course just do 155-30=125. So you'd turn left 125 degrees


As far as question # 2 goes its the same concept. You are on the 165 degree radial. MH+RB=MB So 310+35=345 TOO or 165 FROM (165 is the recipricol of 345)

So 165 radial means you are south east of the station heading northeast. You could technically be on track to intercept all the radials from 165 (the one you already are on) up until 036 if you go way way out. Subtracting 35 deg (the intercept angle) from the 70 deg radial gives you 35 (your heading) so the answer is 70 degrees

hope this made sense, at least somewhat

Cubdriver

HSI or horizontal situation indicator is simply a glideslope/ localizer/ VOR placed on top of a heading indicator. It combines the two instruments into one which turns out to be handy, because now you can look at one thing instead of looking back and forth at two instruments which are inevitably placed some distance apart. This leads to better response times intercepting courses and using back-course localizers, among other things. Since they typically incorporate a slaving mechanism, a system that self corrects for precession, they tend to be more accurate than directional gyros. Some of the better ones do not use gyros and use digital control. Once you get used to them you will never want to go back to separate instruments.

Another improvement over a VOR is that with an HSI, the TO/FROM arrow simply points to the station at all times, whereas with a VOR it gets a bit confusing because the TO/FROM indicator is dependent on whether you have the OBS dialed to an inbound course or an outbound course to the station. For example, if I am west of the VOR station and I dial 090 degrees, I will get a TO indication, and if I dial the OBS to 270 degrees I get a FROM. With the HSI I will get a TO arrow no matter what the OBS is set to and place the CDI on the correct side no matter what you put on the OBS (inbound or outbound course).

Here's a free HSI trainer.

mmaviator

This might help you visual and see a/c and adf/hsi instrument. You can fly the plane and all sorts of good stuff.....enjoy.

Tim's Air Navigation Simulator

PearlPilot

Thank you very much gentlemen, truly appreciate your help. After unsuccessfully reviewing the chapter this morning, I think it's best to sleep on it and start afresh tomorrow...Thanks again!! This helps a lot.
-Pearl

satpak77

learn how to actually FLY with the device, in the sky, in a real airplane, and just memorize the written test answers.

In 20+ years of flying, I have never been on a cross country and used MH+RB = MB in order to get to the destination.

sorry if I ruffled anyones feathers with this response, but some of the written test questions are just that, memorize-the-answer and move on stuff

Cubdriver

I agree with the sentiment of this statement, we all know it is true. But you can see the FAA written as a gentle push to go a little deeper into your flying skills. There is no way a test can be written that contains only useful bits of material, they have to shotgun the subject list and hope it is representative. Worst case you have to study some outdated ideas and techniques, but a little knowledge of prior navigation techniques is not all that bad. I do not like to see students who have no interest in an E6B because they see no daily use for one. I know they are going to be lazy pilots with little or no ability to calculate anything they are doing in the air. I do not really care all that much about E6Bs either, but I do care about the mental discipline the devices can help develop. Same with many of the outdated FAA questions- the mental math you do working these problems can definitely make you a better pilot. Flying is a thinking game as much or more than a video game.

PearlPilot

Just took the test. 94%. Time to focus on the fun part now. Lazy 8s and Chandelles!

lstorm2003

Agree w/ satpak77... Lots of the stuff on the FAA writtens are designed to harass, not teach.

Q: "If you turn 5 degrees off coarse and it measure the time it takes to center the needle again to the station blah blah blah, how many minutes are you away from the station?"

A: Well if you actually turn off your coarse to do this in an actual airplane (which no one does) you'll be able to calculate that if you hadn't gone off course, you'd be home by now.

Just memorize the formula they give you or memorize the answer to the questions. It's one of the single most useless calculations in all of modern aviation.

Cubdriver

Did it ever dawn on you this example with the distance to station is a mental exercise to develop the ability to think clearly about angles, time and distance relationships? And the FAA is just trying to harass people? Your attitude is not what you will need to become a successful instructor. You do not have to go around mouthing false platitudes about written exams, but you should have more respect for the advanced pilots who write these tests- while they are certainly fallible human beings, many of them have thousands of hours teaching behind them and you have let me see, none according to your other posts. It's fine to say you have no idea how a particular concept could ever find practical application to real flying, but to broadly bash the FAA test writers is going a bit too far.

Pearl- nice job! Keep it up.