B737 Downwind to Base Using V/B
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- Опубліковано 19 жов 2024
- In this video will talk about how to use the vertical bearing (V/B) to decide when to turn from downwind to base either in visual approach or radar vectors.
Almost all what I learned about v/b was through the FMC User's Guide. I think it should be a must-read for any B737 pilot.
Utilized this real-time today. Works great. Thank you for the technique.
Glad you found it helpful Christopher,
And thanks for the feedback,
This technique is the most I find resistance about from pilots for some reason.
Thanks again and all the best,
Abdul
godlike technique, easier than mental math and better than chop and drop
I'm currently transitioning from the embaer to the NG and I had gotten very used to flying with FPA and referencing angles bevause the fmc shows the angles between waypoints on the "legs" page.
I thought the 737 lacked information regarding this matter
Loving this feature
Hello Martin,
Pls let me know how the V/B in the 737 compared to FPA in the Embraer,,, I have got mixed opinions from pilots so far.
All the best
Abdul
@Abdulmuati Asiri
Well you could actually fly a FPA using the guidance panel (MCP).
You could also do a vertical direct and fly a straight line vertically to a fix.
Example. I want to reach zzzzz waypoint at 3000ft. Double clicking the altitude LSKlsk (having set set a hard altitude restriction) would show you on the fms legs page, the angle required to reach that waypoint. You could then engage vnav and the airplane would follow that path using pitch. Speed would be controlled with thrust. If the angle was too shallow and or the speed you wanted to fly was too fast then the airplane would use thrust to maintain the airspeed. You could do an idle descent by selecting a speed lower than your actual speed. Of course that if the angle is too shallow you would reach the speed bug and thrust would be needed once again to maintain that airspeed. A very sleep angle would cause the plane to follow the path blindly and airspeed could increase al the way up to mmo or vmo
The other option would be to set FPA on the guidance panel and manually use a know to match the fpa to whatever value you wanted.
The fms would calculate the standard descent with a 3.0°.
It was up to the pilot to increase that angle whenever you were light or had a headwind.
So you had to "build" the descent by playing around with angles
In some sense it was a really basic and rudimentary vnav. The airplane had no regard for speed restrictions if the angle leading to that waypoint was too steep then you would cross either high or at high speed.
The 737 vnav is nicer because all three variations in angle for deceleration are automatically done for you
Thanks Martin for the clarification, the difference between the two is clear for me now.
The V/B in the 737 is not utilized by many pilots but in my opinion once a pilot becomes use to it,,, it is very powerful tool.
Thanks again Martin
All the best,
Abdul
Hello Captain Abdulmuati, I can't get enough from the Tutorial video's from your hand. A total different approach from this approach Technic. What a pleasure it must bee to sit with you in the flight deck. I'am wondering why I don't see you using the fix circles about 5 and 10 miles around the runway. I have also note this into previous video's Do you dislike using those?
I also don't know which area you are flying but I love to see specially you how handeling the LOWI runway 08 with LOC26 approach. But I realize that you do not have to be called or what I want to know. Nevertheless thank you very much for sharing this knowledge and have a nice day. Greetings from the Netherlands. Geert.
Hello G L, thank you for supporting the channel by your participation, I appreciate it.
Regarding the fix page you are right I like to keep the ND display as clean as possible, less clutter. I use the fix of course when I need to but only if I need too.
Where I fly: mostly in Saudi Arabia.
Regarding LOWI I will take a look at the approach you mentioned.
Thank you again, and please do not hesitate to ask any question.
Thank you for responding. I understand it know and it's logic. Bye Bye
Really enjoying this series. I use V/B often but don’t get to fly too many visual approaches like this one. Question: If you were flying a 2.5 mile offset downwind and NOT descending what would be your V/B you would be comfortable turning base at? Using 6.5 degrees is fine if you have those extra track miles to go with the 5 mile offset and continuously in a 1200 fpm descent
Hello Wes,
Thanks for the comment and question, can you please share more on how do you use the V/B in your flying.
regarding your question. For me personally, 3nm is the minimum to do a downwind.
The following is just guessing I have not tried it: I believe it can be done but the descend needs to be aggressive, That is V/S to be increased to the maximum respecting flaps limit speed (may need to be adjusted as required)
The FMC User's Guide talks about an aggressive descend as an option "personally I don't recommend it" which is to use LVL CHNG in downwind flaps 1 and speed of 210, then on base leg gear down speed 190 still LVL CHNG as soon as speed is within flaps 15 limit select flaps 15. This should result in an idle power descend up to flap 30.
I wish I had a more solid answer to your question, but unfortunately or fourteenthly rather I have never been in a situation where I tried it.
Great video again in continuation of “Usage of V/B series”. This makes decent really interesting and fun if one does it this way. It would be great if you can tell me how did you came up with the figure of 6.5 or 5.5 for V/B ?
Hello Shashank,
Angles are mentioned in the FMC User's Guide, and an angle of 8 degrees is mentioned as well although I don't see my self doing it.
1- for the 5.5 degrees, it was through monitoring VNAV. If you build a base and a downwind point that is so the A/P follow LNAV VNAV all the way and delete all altitude restrictions. then VNAV will do the turn at about 5 to 5.5 degrees.
2- For the 6.5 degrees, That is what I found work best for me, but keep in mind I started with 5 degrees then moved half a degree, that is after I was really comfortable. So 5 then 5.5 then 6 and now I am at 6.5 I guess I will not go more than that.
Hope I answered your question,
Thank you again.
Thank you Captain for explaining it in detail. Awaiting upcoming videos and all the best for them
love the video, doesnt the extended centre line automatically appear why did you have to bring one of the way points to the top of the legs page, also for a visual approach can you disregard way point alt constrictions or are they still used ?
No the extended centerline will not come automatically it has to be set manually, that is why you need to select the way point to the top usually the FAF and set the inbound course.
I believe you can descend the altitude for a visual approach, but usually this altitude is usually the right altitude to cross that point, personally I try not to go lower than what is on the legs page.
Hello captain,
Thank you for this practice. I discovered this usage of V/B during approach, and I love that. Today, I flying to Paris, on downwind i was at around 7500ft to reaching 3000ft with speed 200-220kts flaps One initially. When V/B decrease from 6.5 to 6.0, I started to turn from downwind to base and reducing speed gradually, it was perfect on the glideslope. So my question is: We need to reducing very quickly the speed before turn or we can start at 200 or 220kts? Because, in Paris or any other big airport, we need sometimes to keep high speed for the sequencing, so it is possible to use this practice with "high speed"?
Hello Alexandre,
You are most welcome, appreciate you taking the time to leave a comment. 🙏🏼
If you are talking about delaying the speed reduction in the downwind till turning base, I believe it is doable, usually for me the speed on down wind before turning base is about 190.
I would suggest though you aim for a lower V/B before the turn for example starting with V/B of 5.5, experiment with it then move back up to 6 or 6.5.
This is how I started using the V/B to get use to it at the beginning. Take your time be conservative and work your way up.
Hope that help.
Thanks again for leaving a comment,
Let me know if you have any other questions or suggestions or any thing you want to share.
All the best
Abdul
@@AbdulmuatiAsiri37 yes it is! I am glade to learn with your very interesting explanation. I will experiment with 5.5.
But the controller was very surprised by this amazing experiment yesterday ahah.
Today, I tested again, but I was concentrate about my target of 4000ft, so i started to turn at V/B of 3,5. It was very late, and in this circonstance, I can make better. Finally, I need to work again. Thank you!
All the best
Alexandre
Thanks for the Video! Captain I’m doing my line training in the B737NG as FO and I’ve been struggling with visual approaches, specially energy management, and keeping my self aligned with the centerline (always land on the right of the centerline), most of the airport we operate do not have nav aids, all raw data! I wish u could help me with any tip. Thank u
Hello Mauro, wish you all the best in your line training. As requested I will upload a quick video hopefully you will find it of some use.
Please give me the identifier of one of those airports.
Abdulmuati Asiri Thank you u so much Captain, I appreciate.
FNCA & FNUB are one of the airports we operate and FNLU is the base, we prefer to build the approaches using rwy extension of 7nm 3.0 angle and base leg, sometimes we use the RNAV approaches published by Jeppesen but their are very extensive, VNAV LNAV until The FAF, from there FD recycled we continue Visual. No SSR in the country so no radar vectors, no SID, No STAR.. Ur tips have helped me a lot, especially during my assessment, Thank You.
Hello Mauro,
I made a video covering approach and landing, you can find it at this link: ua-cam.com/video/WvWNy5BcxkM/v-deo.html.
It is a rough edit and very loong video but I hope you will find some helpful information in it.
The video is not listed because it is very long and with minimum editing, anybody is more than welcome to watch it and give feedback.
In the future, I am planning to upload more videos on the subject.
Wish you all the best in your flying.
Abdul
Captain! When are you coming back to 737? 😊
Hello Faizal
So far no idea,
I miss you all 😊
Hi cpt
why did you start descending with a vertical speed of 1200 feet per minute (03:00 min)when the required vertical speed was 2000 feet per minute in the fmc
Thank you very match
Hello Nibrasse,
The V/S in the FMC indicates the V/S you need to descend to touchdown from your present position (direct line) so if you are abeam at 3000ft and you are 2nm from the RW it will give you the V/S to lose 3000 ft in 2nm. This is the first point.
The second point is, the A/P will not be able to maintain 1200fpm in the turn with Flaps then from base to final with flaps and gear. So you will see that even though you have 1200fpm set the airplane will vary the V/S between 600-1500.
Third point if you end up slightly above the G/S on final, 1200fpm is a good V/S to make sure you are still descending at a good rate to capture the proper G/P without the need to go with excessive correction.
So I found this 1200fpm as the sweet spot for this technique (for me personally)
Hope that answers your question.
Let me know if you have any other questions
All the best
Abdul
I am convinced and thanks for the quick reply
Thanks
Great Videos! doesn't the plane descend quicker the faster you go. so why add Miles the the faster you go?
I meant to put this in the top of descent video sorry
Hello,
You are right the airplane will descend faster at a higher speed but you have more excess energy to dissipate.
For example lets say two airplanes flying at the same time at the same level lets say 30,000ft one will transition from Mach to 320 indicated on the descend and the other transition to 250 indicated.
Both were asked to descend to cross a waypoint at 10,000ft at 250 indicated.
If we do not factor the speed then the airplane that is descending at 250 indicated will descend at 30,000-10,000= 20,000/1000= 20*3=60nm.
If the other airplane descend at or less than 60nm it will be at 10,000ft before the way point and may even be level, but will still be way faster than 250 indicated. Even the speed brake might not be able to help in the deceleration.
So the excess miles just to make sure we have enough distance to decelerate.
Hope that answer your question.
Thanks again and please let me know if you have any other questions or comments.
All the best
Abdul
AH makes sense! thank you so much you are my favorite 737 youtuber by far!
One more thing, does this descent planning apply for all airliners? Captain Joe uses the same technique and flies a 747.
@@cpt.kentflywright8227 Thank you DnBaviator101 for your kind words really appreciate it.
Regarding your question, I have not used this technique except on the 737.